DGCA issues a notice on the use of Unmanned Aerial Vehicle & Unmanned Aircraft Systems

09 Thursday Oct 2014

Posted by theflyingengineer in Flight Safety

Tags

Aerial, Ban, DGCA, ICAO, UAS, UAV, Unmanned, Vehicle

The DGCA has issued a public notice on the use of Unmanned Aerial Vehicles (UAV) & Unmanned Aircraft Systems (UAS) for civil applications. The public notice, which must be complied with, bans the launch of any UAS or UAV in the Indian Civil Airspace.

Such a directive has been issued in the light of potential safety issues associated with high performance UAVs interfering with flight safety. Recent sightings of ‘UFO’s by commercial airline pilots have only helped speed up such a notification.

The notice, issued on 7th October 2014, will remain in effect till the DGCA formulates regulations associated with the certification & operation of UAS in the Indian Civil Airspace, in line with what the ICAO standardizes.

Impact on Hobby Flyers

Since the DGCA’s regulations concerning UAS/UAV will be in line with those of the ICAO, ICAO definitions and policies may be adopted, in large or in entirety.

ICAO Circular 328-AN/190 concerning both UAVs and UAS, states, “In the broadest sense, the introduction of UAS does not change any existing distinctions between model aircraft and aircraft. Model aircraft, generally recognized as in tended for recreational purposes only, fall outside the provisions of the Chicago Convention, being exclusively the subject of relevant national regulations, if any”.

The DGCA circular may be accessed by clicking here.

Roping in Air Traffic Controllers to help you save fuel, better OTP, and improve safety.

29 Friday Aug 2014

Posted by theflyingengineer in Airline, Aviation, Flight Safety, Human Factors, Incidents and Accidents, Training

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AAI, Air, Airline, Control, Deck Program, DGCA, Flight, Fly, Traffic

The communication between air traffic controllers and pilots is key to efficiency and safety in the air traffic system (ATS). Air Traffic Control Officers (ATCOs) are looked upon as managers : managing the flow of air traffic, and relaying crisp, and necessary messages to pilots.

Effective management is only possible when there is a deep understanding of the technicalities of the lower levels. A manager is always at a ‘higher level’, and decisions are based on a ‘lower levels’ of understanding. Effective management of air traffic is possible only when an ATCO understands, and not just communicates to, a pilot.

Accidents in the past have been due to gaps in understanding between ATCOs and pilots. Fuel burn and on time performance (OTP) are heavily dependent on the decisions taken by an ATCO. Once ATCOs understand aircraft, and aircraft performance, and fuel burn for every extra nautical mile and minute they make airplanes fly, things fall better in place: airline economics, better airport efficiency, and enhanced flight safety.

Read here the steps taken to close the gap between pilots and ATCOs- Jump-seating in scheduled airlines on select routes, by way of Familiarization Flights, which airlines must arrange for.

“Fuel Emergency” & Fuel Quantity: Getting it right

27 Sunday Apr 2014

Posted by theflyingengineer in Flight Safety, Operations, Technical

≈ 3 Comments

Tags

Alternate, Contingency, Delhi, DGCA, Diversion, Emergency, Fuel, ICAO, Mayday, Minimum, Planning, Taxi, Total, Trip

This piece clears the air over a possibly misleading media report in Business Today (BT), “DGCA plans to shut doors on low fuel landings”. The DGCA is right.

Delhi International Airport Limited (DIAL) is known to witness severe fog in winter, which is responsible for a significant number of flight diversions. In the winter of 2011, there were 57 diversions, which steadily grew to 89 in 2012, and 143 in 2013: a 60% yearly growth over the last three years.

To address these now unacceptable number of diversions in winter, the DGCA setup a committee in January 2014 to study the ways in which Delhi may be made a “zero diversionary airport”. The committee concluded the study with a report that included 27 recommendations, one of which was not well understood. Recommendation number 13 states, “AIP shall be amended to indicate that the term fuel emergency would not be recognised at Indian aerodromes.” That recommendation is valid, but was misunderstood by a section of the media.

Further, the BT report stated “DGCA justifies move by saying that airlines are expected to carry at least 1.5 times more fuel than what it actually requires during a flight but they generally carry less fuel.” This too shall be clarified.

“Fuel Emergency”

An airplane is always expected to land with an amount of fuel in the tanks that is above a minimum quantity commonly referred to as “final reserve fuel”. When in flight, if the fuel quantity in the tanks dips below the reserve fuel quantity, the airplane is deemed to be in an emergency. This reserve fuel is the fuel required to fly at 1,500ft above the destination airport, for 30 minutes. For the Boeing 737-800, at typical loads, this is around 1,200kg. Larger airplanes, which consume more fuel in 30 minutes, consequently have a larger weight of fuel as reserve.

Until recently, there was no recommended standard phraseology to be used when the flight crew determined that the aircraft will infringe upon its final fuel reserves before landing. There were two widely used phrases: “Minimum Fuel”, and “Emergency Fuel”. Minimum fuel is an advisory to Air Traffic Control that should there be further delay for landing, the airplane will start eating into the reserve fuel. “Emergency Fuel” was a declaration of emergency, that the airplane has started eating into the reserve fuel. However, the interpretation of this term has been varied, with the FAA recognizing it as “The point at which, in the judgment of the pilot-in-command, it is necessary to proceed directly to the airport of intended landing due to low fuel.” Low fuel does not necessarily mean the final reserve fuel, and is a very subjective quantity.

Unfortunately, a declaration of “Emergency Fuel” would require Air Traffic Control to award the airplane priority. Priority is defined as no further delay into getting the airplane to land. This was reportedly abused by some airlines, including India’s only consistently profitable airline, to ensure that the airplane lands without burning further fuel. That is money saved.

India is a member of the United Nations (UN). The International Civil Aviation Organisation (ICAO) is a UN Agency. ICAO works with member states, and industries and aviation organizations to develop international Standards and Recommended Practices (SARPs) which are then used by states when they develop their legally-binding national civil aviation regulations (CARs). The SARPs ensure uniform best practices, and safe, efficient , and secure flights through commonly understood standards.

Effective 15th November 2012, ICAO has amended ICAO Annex 6 Part I, to include:

“The pilot-in-command shall advise ATC of a minimum fuel state by declaring MINIMUM FUEL when, having committed to land at a specific aerodrome, the pilot calculates that any change to the existing clearance to that aerodrome may result in landing with less than planned final reserve fuel.”

and

“The pilot-in-command shall declare a situation of fuel emergency by broadcasting MAYDAY, MAYDAY, MAYDAY,FUEL, when the calculated usable fuel predicted to be available upon landing at the nearest aerodrome where a safe landing can be made is less than the planned final reserve fuel.”

As a result, henceforth, ’Fuel Emergency’ or ‘fuel priority’ are not recognised terms. India not recognizing these two terms only aligns the country with ICAO standards, helping the country get out of safety audit downgrades.

Further, “Minimum Fuel” is only an advice to ATC, requiring no action by ATC, but “ MAYDAY, MAYDAY, MAYDAY,FUEL” is a declaration of an emergency, in which the ATC must assist the airplane in landing as soon as possible.

Fuel Requirements

DGCA, in its Civil Aviation Regulation (CAR) that covers “Operation of Commercial Air Transport Aeroplanes”, states:

“A flight shall not be commenced unless, taking into account both the meteorological conditions and any delays that are expected in flight, the aeroplane carries sufficient fuel and oil to ensure that it can safely complete the flight. In addition, a reserve shall be carried to provide for contingencies.”

In accordance with the CAR, the airplane must at minimum carry the following fuel, for a flight from Bangalore to Delhi (1000NM), with 180 passengers on a Boeing 737-800W, with an assumption of no cargo. Quantities are derived from the airplane flight manuals and typical airline practices.

No	Term	Quantity 1000kg	Description
1	Taxi Fuel	0.2	The fuel required to taxi from the gate to the runway.
2	Trip Fuel	6.0	The required fuel quantity from initiating take-off to the landing at the destination airport.
3	Contingency Fuel	0.3	Typically 5% of the Trip fuel, but can be as high as 10%. caters to unforeseen circumstances or prediction errors.
4	Alternate Fuel	1.3	The fuel required to execute a missed approach at Delhi and fly to an alternate airport (Jaipur in this case), in case landing at Delhi is not possible, due to issues like visibility.
5	Final Reserve Fuel	1.2	The final reserve fuel is the minimum fuel required to fly for 30 minutes at 1,500 feet above the alternate airport.
6	Extra Fuel	0.0	Based on statistically derived data at the airline, and also at the discretion of the Captain (based on his judgement and reports of a congested airport, or bad weather, or the like.) Assumed Zero for this example.
7	Total Fuel	9.0	The sum of the fuels 1 – 6, which must be uplifted at the departure airport.

If the flight goes as planned, the aircraft should consume only the trip fuel, which amounts to 6,000kg. But the aircraft is filled with 9,000 kg of fuel, which is 1.5 times that of the trip fuel.

One of longest domestic flights into Delhi is from Bangalore, the others being from Chennai and Cochin. As flights get longer, the total fuel will fall below 1.5 times the trip fuel. As flights get shorter, the total fuel will amount to greater than 1.5 times the trip fuel. Since the Bangalore – Delhi flight is one of the longest domestic flights into Delhi, BT’s “DGCA officials” were not off the mark with a ballpark 1.5 figure, but that is a number that is written nowhere, must never be used for planning, and should not have been quoted in the first place. The Mumbai-Delhi sector (which is shorter) will consume only 4,000kg of fuel, but will need to legally carry a minimum of 6,900kg of fuel, which is 1.7 times the trip fuel.

Conclusions

1. The DGCA’s recommendation is not “highly controversial”, as reported by BT. The ambiguous term “fuel emergency” is not recognized and is replaced by standard phraseologies as described above. Flight safety is not compromised but rather improved.

2. DGCA cannot “shut doors” on low fuel landings, as reported. That means you can’t land if you’re low on fuel. What DGCA is doing is to ensure certain standard terminologies are used, doing away with old ones.

2. The laws are not ” draconian”, but progressive to keep up with ICAO standards.

3. A “1.5” figure is not justified, as it depends on many factors. However, if the DGCA official used it to throw a ball park ratio, he’s not off the mark. But later in the BT article is probably a typo which is misleading, “expected to carry at least 1.5 times more fuel“. It must read 1.5 times the trip fuel.

Edit: Added Cochin & Chennai to Delhi as other long flights into Delhi. Thanks to Cyril.

FAA Downgrades India to Category 2

31 Friday Jan 2014

Posted by theflyingengineer in Flight Safety, General Aviation Interest

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DGCA, Downgrade, FAA

As released by the FAA:

The U.S. Department of Transportation’s Federal Aviation Administration (FAA) today announced that India has been assigned a Category 2 rating under its International Aviation Safety Assessment (IASA) program, based on a recent reassessment of the country’s civil aviation authority. This signifies that India’s civil aviation safety oversight regime does not currently comply with the international safety standards set by the International Civil Aviation Organization (ICAO); however, the United States will continue to work with India’s Directorate General for Civil Aviation (DGCA) to identify the remaining steps necessary to regain Category 1 status for India. With a Category 2 rating, India’s carriers can continue existing service to the United States, but will not be allowed to establish new service to the United States.

India achieved a Category 1 rating, signifying compliance with ICAO standards, in August 1997. A December 2012 ICAO audit identified deficiencies in the ICAO-set global standards for oversight of aviation safety by India’s Directorate General of Civil Aviation (DGCA). Subsequently, the FAA began a reassessment of India’s compliance with ICAO standards under the FAA’s IASA program, which monitors adherence to international safety standards and practices. The FAA has consulted extensively with the DCGA and other relevant Indian government ministries during its evaluation, including consultations in India in September and early December, and meetings this week in Delhi.

“U.S. and Indian aviation officials have developed an important working relationship as our countries work to meet the challenges of ensuring international aviation safety. The FAA is available to work with the Directorate General of Civil Aviation to help India regain its Category 1 rating,” said FAA Administrator Michael Huerta.

The Government of India has made significant progress towards addressing issues identified during the September 2013 IASA assessment. On January 20, the Government of India took further steps to resolve outstanding issues when the Indian Cabinet approved the hiring of 75 additional full-time inspectors. The United States Government commends the Indian government for taking these important actions, and looks forward to continued progress by Indian authorities to comply with internationally mandated aviation safety oversight standards.

Additional Background on the FAA’s IASA Program:

As part of the FAA’s IASA program, the agency assesses on a uniform basis the civil aviation authorities of all countries with air carriers that operate or have applied to operate to the United States and makes that information available to the public. The assessments determine whether or not foreign civil aviation authorities are meeting ICAO safety standards, not FAA regulations.

A Category 2 rating means a country either lacks laws or regulations necessary to oversee air carriers in accordance with minimum international standards, or that its civil aviation authority – equivalent to the FAA for aviation safety matters – is deficient in one or more areas, such as technical expertise, trained personnel, record-keeping or inspection procedures.

Countries with air carriers that fly to the United States must adhere to the safety standards of ICAO, the United Nations’ technical agency for aviation that establishes international standards and recommended practices for aircraft operations and maintenance.

General Aviation: Flight Safety Beyond Regulations

21 Tuesday Jan 2014

Posted by theflyingengineer in Flight Safety, General Aviation Interest, Operations, Technical

≈ 1 Comment

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CAR, DGCA, FDM, Flight, FOQA, G1000, Garmin, Logging, Multi, NSOP, Piston, Regulations, Safety, single, Turbine

Deccan Charters’ VT-DCE, which has a G1000 flight deck. The G1000 supports data logging, sufficient for FDM and FOQA needs.

The Flying Engineer explores regulations covering flight recorders, and how even in the absence of the mandate for such devices in single engine and piston aircraft, a commonly found avionics suite allows the operator to tackle flight safety: proactively.

The Indian Director General of Civil Aviation (DGCA), in its civil aviation regulations (CAR) Section 2 Series “I” Part V Issue II, dated 23rd January 2013, covers flight data recorders (FDR), and describes a FDR as “Any type of recorder installed in the aircraft for the purpose of complementing accident/incident investigation.”

The same regulation does not talk about FDR for single engine airplanes. The closest it comes to is a recommendation, for commercial transport, and general aviation, “that all turbine-engined aeroplanes of a maximum certificated take-off mass of 5700kg or less for which the individual certificate of airworthiness is first issued on or after 1 January 2016 should be equipped with: a) a Type II FDR; or b) a class C AIR capable of recording flight path and speed parameters displayed to the pilot(s);or c) an ADRS capable of recording the essential parameters”

A recommendation is not enforceable, and single engine pistons are not covered.

Interestingly, CAR Section 3 (Air Transport) Series C Part III Issue II, dated 1st June 2010, talks of the minimum requirement for the grant of a Non-Scheduled Operator Permit (NSOP). The CAR covers single engine turbine, and single engine piston aircraft as well. The regulation also describes the need to demonstrate a “Flight Operations Quality Assurance (FOQA) and CVR/FDR monitoring system.”

Flight Data Monitoring (FDM) is defined as “the pro-active use of recorded flight data from routine operations to improve aviation safety.” FDM is important, as a review of recorded flight can identify deviations and exceedances, which can be used for corrective training. It is an effective method where an incident is analyzed, and brought to the notice of flight & maintenance crew before it amplifies to an accident.

The surprise here is the DGCA’s realization of the importance of FDM & FOQA in aviation, irrespective of the airplane type, but it’s very regulations do not cover FDRs in single engine airplanes.

Infact, piston engine, whether multi or single engine, are not covered: “All multi-engined turbine powered aeroplanes of a maximum certificated takeoff mass of 5700kg or less for which the individual certificate of airworthiness is first issued on or after 1 January 1989, shall be equipped with a Type II FDR by 31.12.2013.”

Either DGCA assumes that pistons have no future, or that operators, both commercial and general aviation, fly only turbines.

The benefits of FDM

FDM is beneficial for everybody, right from the student pilot to the airline pilot. In training, FDM is necessary to immediately identify exceedances and deviations, bringing it to the notice of the concerned. For example, a student pilot who pulled a high G maneuver may have stressed an airframe, and if before scheduled inspections, the airframe is stressed multiple times, a failure could result. Similarly, a private pilot with 50-60 hrs may make mistakes, which may go unnoticed unless an expert, or a sufficiently experienced person goes through the flight data recordings to understand and point out what went wrong, and how it may be avoided. These are small steps toward enhanced safety for all.

Flight Data Recording without a FDR

G1000 for a Cessna 172

Garmin’s G1000 has been adopted by many airframe manufacturers, making it a standard fit on their aircraft. Cessna for one, offers the G1000 from the 172R to its turbine single engines, including the Grand Caravan.

The Garmin G1000 features flight data logging (FDL), which is not a FDR, but may be used for the same purpose: FDM & FOQA.

On the 172, the G1000 for Cessna: NAV III, logs 64 parameters, at a 1 second interval. These parameters cover (and exceed) the requirements laid down in the regulations for an Aircraft Data Recording System (ADRS), but fall short on only 2 aspects: the recording interval (some data needs to be recorded at 250ms intervals, but is logged in the G1000 in 1 second intervals), and the control surface position (primary and secondary flight control positions are not recorded).

States the Garmin Manual, “The Flight Data Logging feature will automatically store critical flight and engine data on an SD data card inserted into the top card slot of the MFD. Approximately 4,000 flight hours can be recorded on the card.”

In addition, Garmin provides a free, simple to use software that in a few clicks converts the recorded flle to a Google Earth path, which can be viewed in 3D to visually analyze the flight path.

A side-by-side shot of the regions of the MFD where the SD card for flight logging is inserted. One aircraft has it inserted, while the other has it missing, losing the benefits of FDM.

The Flying Engineer has flight data logs from a Cessna 172R for two flights spanning over 2 hours, and the parameters have been so exhaustive that it has supported academic use of the data.

VT-FGE, the ill-fated Diamond DA40CS that crashed in the December of 2013 when on a training flight, has the logging functionality. With the log, it will be immediately clear as to what went wrong, playback of which will prevent other students from repeating the same mistakes.

Unfortunately, schools and some private operators record the data, but do not have a program to pro-actively monitor and analyze every flight, every day, missing an opportunity to self learn and proactively enhance flight safety.

GAGAN Readiness: G1000 with GIA 63W (Diamond DA40NG)

20 Monday Jan 2014

Posted by theflyingengineer in Flight Safety, Technical

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40, 63W, aircraft, DA, Diamond, EGNOS, G1000, GAGAN, Garmin, GIA, GPS, IAU, MSAS, NG, Page, WAAS

With the Indian GAGAN (GPS-aided geo-augmented navigation) system expected to be fully operational by year end, The Flying Engineer visited a Diamond DA40NG today, at Bangalore, to check if the aircraft was SBAS (Satellite Based Augmentation System) enabled, and how GPS information is presented.

GPS is the acronym for the Navstar Global Positioning System, a space-based radio navigation system owned by the United States Government (USG) and operated by the United States Air Force (USAF). Due to its global availability, the Navstar GPS is a Global Navigation Satellite System (GNSS).

A SBAS system, in principle, detects errors responsible for low accuracy and integrity of GPS receiver positions, and broadcasts those errors via geostationary satellites. SBAS enabled GPS receivers apply these corrections, to compute a more accurate GPS position, with 99.99999% certainty. Sources of errors include the satellite (timing errors), and signal propagation delay (as it passes through the ionosphere). Satellite errors are applicable worldwide, but ionosphere errors are location specific.

The Garmin G1000 system relies on the GIA 63 IAU (Integrated Avionics Unit), which functions as the main communications hub, linking all other units (LRUs) with the PFD. Each IAU contains a GPS receiver, a very high frequency (VHF) communication/navigation/glideslope (COM/NAV/GS) receiver, and system integration microprocessors. The GIA 63W (Note the extra “W”) contains a GPS WAAS receiver. WAAS is the United States’ SBAS.

Although labeled as a WAAS receiver, the unit can receive satellite corrections from other operational SBAS as well: Europe’s EGNOS, and Japan’s MSAS, as seen in the photo on the left.

When GAGAN becomes fully operational, supporting ILS CAT-I like GPS approaches, Garmin International is expected release a navigation database update cycle that will allow the Garmin G1000 display units to list the GAGAN system under “SBAS Selection”. It may then be prudent to de-select WAAS, EGNOS and MSAS, and select only GAGAN.

The GPS Signal Strength box, as seen in the GPS Status page, in the photo on the right, shows the GPS satellites (these satellites have a code, called a PRN (Pseudo Random Noise), between 1 and 32), and the SBAS satellites (124, 126, 129). Satellite 124 is Artemis (EGNOS), 126 is INMAR3F5 (EGNOS), and 129 is MTSAT1R (MSAS).

GAGAN’s SBAS satellites, GSAT-8 and GSAT-10, will be seen as satellites with PRN 127 and 128, respectiely.

The green bars show satellites that are actually being used in the position calculation, the height of the bar proportional to the signal strength. The blue bar shows satellite 25 is locked on but not yet being used in the position calculation. The hollow signal strength bars for satellites 31, 126 and 129 show that the receiver has found the satellite and is collecting data, before the satellite may be used for navigation, and the bar becomes solid. No signal strength bar, as seen for satellite124, shows that the receiver is looking for the indicated satellite.

The “D” indication on signal strength bar shows that the satellite is being used for differential computations. The differential computations, which is the consideration of the “error” to improve positional accuracy, is based on transmissions from EGNOS and MSAS. Since India is not in the intended geographical coverage area of EGNOS or MSAS (see image above, courtesy AAI), Ionosphere corrections are unavailable, but satellite error corrections, which are globally valid, are available, and being used.

With these corrections, the Estimated Position Uncertainty (EPU): the radius of a circle centered on the GPS estimated horizontal position in which actual position has 95% probability of lying, is 0.05NM, as seen in the Satellite Status Box.

The Horizontal and Vertical Figures of Merit (HFOM and VFOM), seen as 23ft and 33ft respectively, is the current 95% confidence horizontal and vertical accuracy values reported by the GPS receiver.

Based on GAGAN’s trials by the Airport Authority of India (AAI), the observed accuracies are 3ft horizontal and 5ft vertical: a dramatic increase in positional accuracy, which the same aircraft will observe when the GAGAN is switched on for civilian use: something that is hoped to happen by the end of Jan 2014, as per the AAI General Manager (CNS) heading the Ground Based Elements of the GAGAN Project at Bangalore, India.

GAGAN: “Approach” Benefits

19 Sunday Jan 2014

Posted by theflyingengineer in Flight Safety, Operations, Technical

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Approach, APV, GAGAN

Some line pilots have asked how the GAGAN system (equivalent to the WAAS in the US and EGNOS in Europe) will benefit operations, considering Cochin already has a GNSS approach to Runway 27.

With the GAGAN fully deployed with APV 1/1.5 (Approach with Vertical guidance), expected by end of year 2014, after the GAGAN RNP 0.1 is activated (expected anytime this month), GPS approaches with qualified equipment, and in some cases qualified air crew, are instrument precision approaches. The present GNSS 27 at Cochin is a non-precision approach. (see chart on the left)

The major difference lies in three aspects: accuracy, integrity, and vertical guidance. With GAGAN, GNSS accuracy is further enhanced, leading to greater confidence in the approach. With integrity (pilots getting a warning should the performance degrade), confidence in the system is further enhanced, allowing not just operators, but the regulator to approve instrument precision approaches. The precision is because of the enhanced GPS accuracy and integrity, which allow the aircraft to descend on a glide slope generated with the help of the GNSS’s vertical guidance.

The chart clearly shows that lateral guidance is provided by the GNSS, and vertical guidance by a barometric system: the altimeter. This non-precision approach has a minimum descent height(MDH) of 430 feet, and a “decision height” of 410 feet, though vertical guidance is not precision.

With an APV, the approach becomes precision, with minimums between 200ft and 250ft. The approach is now precision, and the decision height is similar to ILS CAT I. In case the vertical performance of the GNSS degrades, it becomes an LNAV / VNAV approach, with minimums as published in the chart.

Such approaches can be very quickly published at many airports, without the need for a costly ILS system. This will allow many operators to exercise an APV at airports, leading to higher flight safety in one of the most critical phases of flight: the approach. In addition, operator can fly into an airfield even in weather conditions that will prohibit non-precision approaches, if an APV approach is published at that airfield, no matter how remote or deserted it may be.

Understanding the Ultimate Load-Wing test: A350

14 Tuesday Jan 2014

Posted by theflyingengineer in Flight Safety, General Aviation Interest, Manufacturer

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A350, flex, G, Load, test, Ultimate, Wing

The Airbus A350 program achieved another milestone with the successful completion of the ultimate load wing test in December 2013. The ultimate load wing test is a test in which the wing is deflected to simulate the “ultimate” load, beyond or at which the wing is expected to fail.

The ultimate load is calculated as 2.5 times the maximum expected G load that the aircraft would ever encounter in its service life. For the Airbus A350, which is limited in the G loads that it may experience, by the Fly By Wire system to +2.5G, or with the FBW system deactivated, as is the case with a reversion to direct law, approximately between 3-3.5G with the aerodynamic limitations of the flight control surfaces. The ultimate load is then possibly between 7.5 – 8.75G.

Based on this G force, the expected wing flex due to aerodynamic loading is computed, and the wing of a static test airframe flexed (loaded) to the corresponding load. The wing is expected not to fail at this “ultimate” load equivalent flex. At this loading, the A350’s wings flexed in excess of 5 meters, while at a similarly scaled G loading, the A380’s wings flexed to close to 7.5 meters. The 787’s wing flexed up to 7.6 meters in a similar test, mandatory for certification.

In February 2006, the A380’s wing gave way just before the 1.5 times greater G load limit was reached.

Unlike in the past, aircraft manufacturers don’t seem to be stressing the wing beyond 1.5 times greater load, to the point of wing failure. The actual failure load may not be known.

According to Airbus, “This test was performed on the A350 XWB static test airframe that was built specifically to demonstrate the structural integrity of the airframe. The strains induced into the airframe were measured and monitored in real time using more than ten thousand measurement channels. The huge volume of data recorded was analysed and correlated to the structural computer models which have been used to design the airframe.”

With the comforting thought of a safe-enough wing, the first A350 airframe intended for commercial service, MSN6, is being assembled for launch customer Qatar Airways.

Southwest 4013: Pilot Error? Unlikely.

13 Monday Jan 2014

Posted by theflyingengineer in Flight Safety, General Aviation Interest

≈ 11 Comments

Tags

700, 737, Boeing, KBBG, KPLK, land, N272WN, Southwest, SWA4013, wrong airport

Another 300ft, and the Boeing 737-700 N272WN would have rolled 60ft down the embankment, resulting in an accident

A Southwest Boeing 737-700 registered N272WN, operating as Southwest Airlines flight 1403 scheduled to land at Branson Airport (KBBG) from Chicago Midway (KMDW), landed instead at M. Graham Clark Downtown Airport (KPLK), about 5NM to the north of the intended destination airport.

The incident happened on 13^th Jan 2014 at ~00:11 UTC (12^th Jan 2014 18:11 CST).

The 737 landed on Runway 12 at KPLK (3738ft long x 100 ft wide), and stopped right on the piano keys of runway 30, leaving just 300ft to the edge of the 60 ft embankment on which the ends of the runway sit. The tires were reportedly “smoking” with the intensity with which they were applied.

METARs Read:

KBBG 130055Z 18011KT 10SM FEW250 15/M02 A2971
KBBG 122347Z 15012G23KT 10SM FEW250 17/M02 A2970

The runway at KBBG is oriented 14-32 (7140ft long x 150 ft wide). It is difficult to understand how the pilot may have landed at KPLK instead of KBBG. Pilot error seems unlikely, as the pilot may have initiated a go-around seeing runway “12” instead of “14” or “32” that may have been expected at KBBG. KBBG has an ILS approach for runway 32 and two RNAV GPS Approaches for 14 and 32, either of which may have been strung into the FMS.

Sunset in the area was 17:18 local time, and civil twilight till 17:46 local. The aircraft landed in the absence of natural light. KBBG and KPLK both have runway edge lights, but Runway 14 and 32 at KBBG have PAPIs (Precision Approach Path Indicator), while KPLK has no visual approach aids for runway 12. Further, the hangars and terminal building for KBBG are on the left (when approaching runway 14), while those at KPLK are on the right (when approaching runway 12).

Based on Flightaware’s track of Southwest 4013, the aircraft deviated from its intended flight path 111 NM away: possibly indicating an intentional deviation from the flight path at or close to the top of descent. The airplane’s track seems to have drifted to the north-northwest, while winds generally blew from south-southeast. This track shift can occur if the airplane’s flying on the heading mode, but may easily get noticed as a deviation from the active flight plan route on the navigation display in the cockpit.

SW1403 started deviating from its track close to its TOD, 111NM away from KBBG

So, we have 2 pilots in a 737-700 that has an INS (Inertial Navigation System) with periodic VOR-DME / DME-DME position updates, augmented by a GPS, that together can compute the aircraft’s position with great accuracy, and displays the planned route from Chicago Midway (KMDW) to Branson Airport (KBBG). This combination of man-machine seems unlikely to land at the wrong airport. Or did the crew enter the wrong destination? Highly unlikely, considering that pilots usually select the company route rather than punching in the route manually. Further, the route is usually cross checked with the filed flight plan. And yes, Southwest does not fly its Boeings into KPLK: the runway is, evidently, too short; choosing a wrong route seems unlikely.

Did the pilots get the automation mode wrong, and fly a heading rather than LNAV? Even if they did, the aircraft’s position would have clearly shown a deviation from the active flight plan. Did the pilots miss the building and hangar lights that somehow was on the right instead of the left? possible. Did the pilots notice the absence of the PAPI? unlikely. It was dark, and they would have very much noticed the PAPIs absence, or relied on the GPS approach to KBBG, which would have shown them that they were far off the field.

In short, everything about this approach somehow does not seem to point solely towards pilot error.

Preparing for GAGAN: SBAS vs Non-SBAS Receiver

11 Saturday Jan 2014

Posted by theflyingengineer in Flight Safety, General Aviation Interest, Technical

≈ 4 Comments

Tags

EGNOS, GAGAN, Garmin, GPS, MSAS, Nokia, Receiver, SBAS, WAAS

GAGAN’s GSAT 8 (closer to Africa) and GSAT 10 provide the SBAS correction & integrity signals.

With the GPS Aided GEO Augmented Navigation (GAGAN; Indian term for the country’s SBAS system) availability just a few days away, excitement is in the air, especially those who realize the benefits of the Satellite Based Augmentation System (SBAS) and the benefits it brings to aviation applications.

Today, we get to see the Wide Area Augmentation System (WAAS; US term for their SBAS system) as an option on a high sensitivity WAAS enabled Garmin receiver, and how it compares with a non-specialized commercial grade GPS receiver (A Nokia E-72 was used for this).

The Garmin unit picked up 11 Satellites, while the Nokia E72 picked up only 8 (blue bars). Note that the Nokia GPS cannot receive signals from satellites beyond #32.

The Garmin handheld unit (eTrex-H, now a discontinued model from Garmin, but used by many for aviation applications, though not certified for such use) features a high sensitivity receiver. With higher sensitivity, it can pick up weak GPS signals, which are too weak for standard sensitivity GPS receivers to pick up. As a result, it receives signals from more satellites, making the reported position very accurate and stable. (with a 3 meter accuracy, you can be assured of landing within 10ft on either side of a runway centreline)

The Garmin Unit’s accuracy was rock solid stable at 3 meters, while the Nokia’s accuracy fluctuated, and came nowhere close.

In addition, the Garmin eTrex-H also has a the ability to receive signals from ANY SBAS satellite, and apply the necessary corrections to make the signals more accurate. Considering that the GPS unit already has an accuracy of 3m, it may be unlikely that a greater accuracy may be noticed with the WAAS system, although the corrections will be applied. This is because, closer to the equator, the ionosphere introduces a lot many errors, which disturb the GPS signals. An SBAS attempts to provide a 7 meter accuracy; anything better than that must be treated purely as a bonus!

WAAS ellitenabled, and the Garmin unit looking for Satellite 39 from EGNOS

In the settings, WAAS was enabled, and as a result, the Garmin GPS unit received satellite number 37 (Jan 10) and 39 (Jan 11). A standard non-WAAS / SBAS receiver will not see more than 32 satellites. GPS satellites have a PRN (Pseudo Random Noise code that allows the receiver to decode that specific satellite’s information) between 1 and 32, both inclusive. Any satellite beyond 32 is a SBAS Satellite, part of WAAS, EGNOS (the European Geostationary Navigation Overlay Service), MSAS (Multi-functional Satellite Augmentation System (Japanese)), or, as will be seen in a few days, the GAGAN system’s. Satellite numbers 37 and 39 are from the European EGNOS, but the corrections received will not be applied by the receiver as the satellite signals specify the area of applicability.

The GAGAN system’s satellites, with a PRN of 127 (GSAT-8) and 128 (GSAT-10), will appear as satellites 40 and 41, respectively, on a GPS receiver. Both satellites transmit the same information. That satellite from which the GPS receiver receives stronger signals will be selected. For Bangalore, this is GSAT-10 (Seen on the GPS receiver as 41).

The excitement is building!

Within 5 days, India’s navigation system will be “Stellar”!

09 Thursday Jan 2014

Posted by theflyingengineer in Flight Safety, General Aviation Interest, Technical

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Augmentation, GAGAN, GPS, Launch

GPS Satellites from which signals could be received at 2145IST (1615UTC) on 9th January 2014.

The Flying Engineer visited the Master Control Centre of the GAGAN system, the equivalent to the United States’ WAAS. This piece talks of the GPS system, as available today, and the changes expected, in a few days, to aviation navigation in India.

Navigation information may be from a self contained source (such as an inertial navigation system), or from land external radio aids, such as VOR, DME, ILS, NDB (almost on its way out), or from space based radio aids: Satellites. The most commonly used satellite navigation system is the NAVSTAR Global Positioning System, popularly known as the GPS.

The GPS signals as received by the on-board GPS receiver of a Nokia E-72. The screenshots are for different orientations of the phone: North-East-South-West. As seen at 21:37 IST (16:07UTC) on 9th December 2014.

A simple GPS receiver in a mobile phone (I didn’t pull out my Garmin as the battery is dead) can show you the satellites in the vicinity, and the positional accuracy. If you’ll notice, the mobile phone receiver shows 32 slots for 32 possible active GPS satellites (identified by their PRN number: see the table below), not all of which are in the line of sight of the receiver at any given point of time, as the satellites orbit the earth. GPS signals are weak, and hence by making the mobile phone face North, East, South and West, different satellites could be picked up, all those which were “visible” (line of sight) from the ground (see the table of satellites).

GPS Satellites “visible” over Bangalore as of 2146IST (1616UTC). This table matches with the GPS satellites visible on the phone.

The advantage with a satellite based navigation system, such as the GPS, which offers navigation signal coverage globally, and hence called GNSS or Global Navigation Satellite System, is that it overcomes line of sight and range issues associated with all land based radio aids, and doesn’t drift like the INS. Today, most aircraft have a GNSS receiver on board, and is used to supplement navigational information obtained from the VOR, ILS, and the INS, if present on board.

The “supplement” in the statement above must be paid attention to. Because a GNSS’s control is exclusively in the hands of just one country / union, other countries do not have a way of controlling or monitoring the signal. Further, errors that creep into the signal as it passes through the ionosphere degrade the positional accuracy. Hence, on all airplanes in India, “GPS Not to be used for Primary Navigation” is often seen in the flightdeck, especially in general aviation (GA) aircraft, even though the accuracy of GPS receiver is greater than that of a VOR, and the INS, but worse than that of an ILS.

Note the horizontal and vertical accuracies, which are sufficient for enroute, but poor for a precision approach.

The GPS system (which includes the receiver) guarantees an accuracy within 100m (0.05NM), but practically observed GPS accuracies at the receiver level are encouraging: usually, the accuracies go up to 3 meters for good receivers with higher sensitivity (like a simple handheld Garmin eTrex H), and is around 10-40 meters for GPS receivers like those found in mobile phones. With 0.05NM accuracy, it may immediately seem evident that with a GPS receiver, an airplane can comfortably fly a RNP 0.1 route / arrival.

It can, but it may not. The problem is that, if all the satellites behave equally bad, (or ionospheric disturbances introduce too much error), fooling the GPS receiver into believing that it is computing a valid, accurate GPS position, the outcome may be as bad as a controlled flight into terrain (CFIT). There must be a means to inform pilots if the GPS signals are not reliable. That requires a second system based on the GPS, that monitors the GPS signal’s integrity, and lets users know if the signals are reliable or not. Once information about integrity is made available to pilots, GPS may be used to navigate, for as soon as the signals go bad, pilots will receive a notification which will allow them to discard GPS data, and switch to land based radio navigation aids to continue navigating safely, and sufficiently accurate.

In India, this role of monitoring the signals is the responsibility of the GPS aided geo augmented navigation (GAGAN) system. The GAGAN system has 15 ground stations scientifically scattered across the India, to monitor GPS signals. The system offers integrity monitoring only within India’s flight information regions (FIRs), besides providing information that allows GPS receivers to compensate for errors induced due to either the satellites or the propagation through the ionosphere. This make the GPS receivers determine position with far greater accuracy: as much as 7.6 meters, with a guarantee.

In 3-5 days from today, the GAGAN system will be switched on, available to everybody, not just to airborne receivers. However, the information crucial to aviation, which is reliability & accuracy, needs something more than a normal GPS receiver. The GPS receiver needs to have the ability to receive the additional information: about signal integrity, and error information (that may be applied to increase accuracy). This information is made available through additional satellites: in the case of the GAGAN system, these are satellites with codes 127 and 128, transmitted by the Indian GSAT-8 and GSAT-10, respectively. GPS receivers which sell with a “WAAS-enabled” tag (like my Garmin eTrex H) will be able to offer the accuracies promised.

WAAS enabled Airborne GPS receivers, such as the Garmin GNS530W (Note the “W” for WAAS) will be required to fly in Indian airspace, if the aircraft is to fly a GPS arrival, approach, or route. These receivers are readily available, and when installed, the “GPS not to be used for primary navigation” will be a sticker of the past.

January 5th: A day of Incidents and Accidents

06 Monday Jan 2014

Posted by theflyingengineer in Flight Safety

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200, 600, 767, A320, Accident, Air, Airbus, Aspen, Boeing, Bombardier, Challenger, CRJ, Emergency, HS-BKE, Incident, India, Jaipur, N115WF, Saudi, Spicejet, VT-ESH

The black book of aviation safety suddenly experienced a spike in entries on January 5th, 2014. There were three accidents and one incident on Jan 5th, 2014. There was only one fatality.

At around 01:00UTC, A Saudi Boeing 767-300, registered HS-BKE, landed at Madinah (Saudi Arabia) with the right main gear still retracted. The crew were first made aware of the situation when they were on approach, and extended the gear only to observe an unsafe indication for the right main. The crew put the aircraft into a hold, followed applicable checklists, including what appears to be a gravity extension, but after being unable to resolve the issue, landed on the third attempt, on the left main, and the right engine. There were no injuries as a direct result of the accident, but because of chaos during the evacuation. The aircraft seems to have sustained substantial damage.

At around 13:00UTC, a Bombardier CRJ200 registered N8758D, landed at New York’s (USA) John F Kennedy’s runway 22L, and slid off the taxiway exit J, and came to stop on soft ground, temporarily shutting the airport for 2 hours. No injuries were reported.

At around 14:00UTC, an Airbus A320-231 with the double bogey landing gear, registered VT-ESH, landed at Jaipur International Airport (India), burst its tyres, and damaged its left wing significantly. The aircraft was operating a scheduled domestic into Delhi, but was forced to divert to Jaipur due to visibility at Delhi, where it declared a fuel emergency and reportedly landed below minima (landing in visibility below the allowable runway visual range (RVR)), due to a fuel emergency. Uncertainty remains on the cause of wing damage: whether the wing scraped the ground, or the wing hit obstacles after reportedly (but unlikely) veering off the runway after landing. The closure of Jaipur Airport due to this accident forced a Spicejet 737, registered VT-SGU, which was supposed to have landed at Delhi, but was forced to divert to Jaipur due to visibility, to return to Delhi, where it declared a fuel emergency, and reportedly landed below minima.

At around 19:20UTC, a Bombardier Challenger 600 registered N115WF, reportedly land, turn into a fireball, flipped a few times, and skid to a stop, upside down, on runway 15 at Aspen-Pitkin County Airport, CO (ASE, USA). The accident left the airplane charred, took the life of one on board, while seriously injuring another, and mildly injured the third person on board. The right wing had snapped off. The aircraft had executed a go around, citing a tailwind, and came to rest in this condition on the second landing attempt. Other traffic had reported mild windshear and gusting winds.

Training aircraft goes missing, crashes.

24 Tuesday Dec 2013

Posted by theflyingengineer in Flight Safety

≈ 8 Comments

Tags

Accident, aircraft, country, Crash, Cross, Diamond, FGE, Gondia, IGRUA, Missing, Navigation, Panchmarhi, Training, VT

UPDATE02: Nullifies Update01. Director of IGRUA, Air Marshal (retd) VK Verma confirms that the aircraft / wreckage is not found, and that Search and Rescue are still underway. Although the situation hints at an undesirable outcome, we apologize for bringing out the previous update.

UPDATE01: Reportedly VT-FGE’s has crashed, taking the life of the student pilot.

A 4 year old Diamond DA 40 CS (similar to above photo) bearing registration VT-FGE went missing on a training flight today (24^th December 2013). The aircraft departed Gondia at 07:09UTC (12:29 IST) for a navigation cross country to Panchmarhi and back. The aircraft was expected to return to Gondia at 09:16UTC (14:46 IST).

The last known position was 63NM on Radial 359 from Nagpur Radar, at 0745UTC (1315IST). This places the last known position of the aircraft on the route from Gondia to Panchmarhi, with no apparent deviation. This last know position is overhead the village of Raja Khoh, Chhindwara, Madhya Pradesh, and 80NM from Gondia.

The distance between Gondia and Panchmarhi is 120NM, and was the first long navigation cross country flown by the IGRUA cadet (name withheld upon request). The cadet has about 90 hours total time. The cadet was the only occupant, on board.

Terrain around Panchmarhi

Panchmari, a hill station, which is at an elevation of 3,600ft, is known to be notorious for its terrain, turbulence and poor visibility. Panchmari has a mud, unmarked runway oriented 04-22.

Search and rescue operations have been commenced, but the aircraft hasn’t been located. No ELT signal has been received, pointing either to a soft and safe landing of the aircraft in an open field, or the malfunction of an ELT in a crash. We sincerely hope the former is true. No call has been received from the cadet’s mobile phone, which was with him. No distress calls were heard.

The endurance of the aircraft is 04:00hrs, and at the time of writing this piece, the aircraft departed 10:15hrs ago.

China Airlines 120: Downstop Failure Animation

17 Sunday Nov 2013

Posted by theflyingengineer in Flight Safety, Technical

≈ 1 Comment

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120, Accident, Animation, Burn, China, Explosion, Flap, Fuel, Incident, Investigation, Puncture, Slat, Tank, Track

Photo: FAA/AFP/AP

On August 20, 2007, a Boeing 737-800 registered B18616 (Boeing MSN 30175) operating as China Airlines Flight 120 departed from Taiwan, Taoyuan International Airport on a scheduled flight to Naha Airport, Okinawa, Japan. The aircraft caught fire, and exploded after taxiing and parking at the gate at Naha Airport.

While initially it appeared as a freak case of a spontaneous Boeing 737NG’s combustion, investigation has reveled the true cause of the incident which is very, very interesting. While there can be a textual description of the findings, it is best explained through this very clear animation, and will be best appreciated by maintenance engineers and technicians. Not a single screw, or washer must be left behind. After all, the manufacturer spends years researching and bettering the airplane, and the combined experience that goes into designing the airplane far outweighs the combined experience of all technical staff in any single airline.

Watch the FAA animation HERE. (LINK).

ATR 72-600 Crash & Official Statement (Excerpts)

17 Thursday Oct 2013

Posted by theflyingengineer in Flight Safety

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600, 72, Airlines, ATR, Crash, Lao, Laos

An ATR72-600 in Lao Airlines paint scheme, similar to the one that crashed. Photo: ATR

A Lao Airlines ATR 72-600 crashed on the 16th of October, 2013, at around 4:10pm local (0910Z) near Pakse, Laos.

The aircraft, registered under RDPL-34233, was MSN (Manufacturer Serial Number) 1071, delivered from the production line in March 2013. The brand new airplane was operating as domestic flight QV301 between Vientiane(IATA: VTE, ICAO: VLVT) and Pakse (IATA: PKZ, ICAO: VLPS) with 44 passengers and 5 crew members on board. All 49 on board are feared no-more.

The great circle distance between between Vientiane and Pakse is 250NM. Part of the flight occurs over neighboring Thailand. The crash seems to have happened when approaching runway 15 of VLPS. The aircraft crashed about 5NM from touchdown. Weather is a suspect, considering cyclone Nari’s effect on the region.

The runway at Pakse is 5332 feet long. The airport has a VOR, and NDB, but no ILS. The airport is co-operated by military and civilian authorities.

Lao Airlines was founded in 1976. In 1995, the airline received its first ATR 72. According to the airline, the ATR 72s (4 ATR 72-500 + 2 ATR 72-600 including one that crashed) form the backbone of the carrier’s fleet for international and major domestic services. Its fleet also comprises 4 Airbus A320 and 4 Xian MA60. The Chinese aircraft fleet is due to the country’s closer links with its Eastern neighbor. Laos was a French colony between 1893 and 1949.

Key points of ATR’s official statement include:

“At this time, the circumstances of the accident are still to be determined. Official sources of Lao Airlines declared that “the aircraft ran into extreme bad weather conditions and was reportedly crashed into the Mekong river. There were no news of survivors at this time”.

The Laos’ Authorities will lead the investigation and will remain the official source of information. In line with the ICAO (International Civil Aviation Organization) Annex 13 convention, ATR will provide full assistance the French Bureau d’Enquêtes et Analyses (BEA), safety investigation authority representing the country of the aircraft manufacturer.”

Radio Etiquette

09 Tuesday Apr 2013

Posted by theflyingengineer in Flight Safety, General Aviation Interest

≈ 4 Comments

Tags

Air, Bhopal, Etiquette, India, Radio

We were approaching Bhopal, when an Air India A321 bound for Mumbai requested pushback from ATC. A few minutes later, Bhopal cleared us to land, as we left our hold near the right base, for finals.

Even before we could turn into finals for Runway 30, the commander of the Air India 321 started “complaining” of how the aircraft was pushed-back facing south-east, and the winds blowing into the rear of the engine stalled the engine-start process. He ranted on, and on, about how the ground crew wouldn’t push him facing the wind, as they needed permission from ATC, and that the ATC must advice the company handling ground crew to push them back facing the wind.

The Air Traffic Controller, shot back a long, lengthy reply on why it was not possible, and the sorts. The argument of each was right, and the discussion just short of breaking into a fight, and for the rest of us, enlightening and amusing. When the debate was over, we were on terra firma.

But it is hardly amusing when you’re on finals in a small airplane, and you can neither transmit nor request for the surface winds. It gets even less amusing when, let’s say, you witness an airplane incursion, and neither the ATC can transmit, nor can you state you intention to go around. And when you go, around, you will have to bank hard to avoid that Bell 429 that is flying toward its helipad. Or even worse, you suffer an engine fire and you are forced to land, but there is some inattentive bloke in that Piaggio Avanti, who is on the active. Or you execute a go-around, and the Piaggio pilot, so fed up with the controller that he thinks the coast is clear and applies power for takeoff, will find two airplanes, one executing a missed approach, and himself on a high speed departure, with no TCAS on board one of the airplanes. Thankfully, none of those happened that day.

The Air India commander is at fault. With a minimum of 5000 hours under his belt, he started “talking” on a frequency when there were multiple approaches. The ATCo worsened the situation, by choosing not to a) ask the captain to switch to another frequency where the issue may be resolved or b) request the captain to hold as there were multiple aircraft inbound into the field and one on finals.

Instead, the ATCo chipped in, and held the PTT button pressed till he was satisfied with his own reply.

It’s not an FRTOL or RTR-A that makes you a better person. Neither is it hours of manning the ATC or flying a jet that matter. You just need a bit of common-sense. Awareness. And Radio Etiquette. All part of good airmanship.

RNAV and RNP in India – Airways

07 Sunday Oct 2012

Posted by theflyingengineer in Flight Safety, Operations

≈ 17 Comments

Tags

AIPS, Air India, Air Traffic System, AIS, ANP, Delhi, ENR, Fuel Saving, ICAO, India, Indigo, Mumbai, Navigation, Q1, RNAV 5, RNP, W13N

Change in aviation is met with heavy resistance, and even a ten year old technology is considered relatively new. With the introduction of Performance Based Navigation (PBN) in the Indian Airspace, confusion still exists on RNAV (aRea NAVigation), RNP (Required Navigation Performance), and where this RNAV/RNP are implemented in the Indian ATS.

Waypoint LATID, seen as referenced to Bangalore International Airport’s VOR (BIA).
LATID = BIA/012deg/77NM or N14 28.6 E077 56.9

The basic airway system (in India and the world over) was constructed based on sensors: the VOR and the NDB stations and receivers on board the airplane, which provide the capability to fly to, or from a radio station along one of its “radials”. These radio stations are scattered, purposely, across the country, and the airway system is constructed by simply “connecting the dots”, and an aircraft’s position is always relative to one of these stations. Example: Waypoint LATID is 77NM from Bangalore International Airport’s VOR (BIA), on a radial of 012°of BIA.

When an aircraft’s navigation system has a little more intelligence: the ability to scan and receive signals from multiple such radio ground stations, or from self contained navigation aids, such as the Inertial Reference System (IRS), or from the globally available GPS satellite constellation, and determine the aircraft’s position in terms of the World Geodesic System 1984 (WGS-84) coordinates, it provides the ability to determine the aircraft’s absolute position, rather than referencing it to a sparse set of radio stations. Example: Waypoint LATID is N14° 28.6’ E077° 56.9’.

The advantage with absolute position is freedom in the lateral: an aircraft can determine its absolute position, and fly to another waypoint whose absolute position is known, without having to stick to a “radial” or a VOR station. The ability to fly “Direct-To” another waypoint from the present position offers an easily comprehendible advantage: fuel savings through shorter, more direct routes. This freedom in the lateral, and the ability to navigate freely in an area, gives rise to RNAV, or Area Navigation.

Indian airspace is comprised mostly of “W” routes, which are, as per AAI, exclusively available for domestic operators only. According to ICAO Annex 11, a “W” route is NOT an Area Navigation Route, which means, the airway is constructed with reference to ground radio beacons, and are mostly direct from one beacon to another.

The other airways in India are “A”, “B”, “G”, “L”, “M”, “N”, “P”, “Q”, “R”, “UL”, “UM”. Of these, “L”, “M”, “N”, “P” and “Q” are area navigation routes. This means that these routes are not constrained to fly between ground based radio stations, but are instead optimised, more direct routes that save fuel. The “Q” routes were recently introduced in 2012, in July.

Since flying these routes implies a reliance on the aircraft’s complex navigation system (which authorities have no operational control of) rather than the simpler ground referenced navigation system (which authorities maintain), it is imperative that in the interest of safety, the complex area navigation system be capable of a certain navigation accuracy, also termed the navigation performance.

Certain routes, and certain procedures may require a higher navigation accuracy and its associated certainty, while others may be less demanding. To quantify these “higher and lesser” accuracies, the term “Required Navigation Performance” (RNP) was introduced, which stipulates the minimum navigational accuracy that must be guaranteed, with a certainty of 95% availability.

With RNP, of the many requirements, the aircraft must be capable of displaying the Actual Navigation Performance (ANP). As long as the actual navigation performance is within the limits of the RNP, everyone’s happy. But if the ANP gets worse than the RNP, that’s when Air Traffic Control must be notified so they can keep close eye on you and other airplanes in relation to your aircraft, and direct you based on conventional navigational practices.

The Area Navigation Routes – “L”, “M”, “N”, “P” – are all RNP 10 in India. The newly introduced “Q” routes, are all RNP 5. This means that your aircraft’s navigation accuracy must be better than 5 NM if it is to fly along the newly introduced 7 “Q” routes: Q1 – Q7. If however the ANP of the aircraft is 5.5 NM, then the accuracy is not enough to fly the “Q” routes, but accurate enough to fly thee RNP 10 routes: “L”, “M”, “N”, “P”.

Q1, W13N, and a Direct route as shown between Mumbai (BBB) and Delhi (DPN) VORs

The benefits of the RNP routes are evident. The newly introduced “Q” routes connect Delhi to Mumbai, Ahmedabad, Udaipur, and Vadodra. Picking “Q1”, which is Mumbai to Delhi (BBB- DPN), there are 13 waypoints in between the starting (BBB) VOR and the ending (DPN) VOR. Except for one, none of the other waypoints are ground based radio aids. The total ground distance between Mumbai and Delhi along Q1 is 633NM. The domestic non-RNAV “W13N” route between Mumbai and Delhi, has 5 waypoints in between, three of which are ground based radio aids (VOR). The ground distance along W13N is 653NM. A347, another non-RNAV route between Mumbai and Delhi, has 9 waypoints in between, three of which are ground based radio aids. The ground distance along A347 is 735NM. Compared to W13N and A347, Q1 saves 20NM and 102NM of ground distance, which translates to a saving of between 2 minutes and 14 minutes of flying time. A heavy Airbus A320, flying at FL350 at 76Tonnes, can save between 124 kg and 634 kg of fuel, which translates to a saving of between INR 11,000 and INR 56,227 per Mumbai-Delhi flight. Another advantage is the smooth flight path, as opposed to the zig-zag of non-RNAV routes.

Indigo’s 11 daily direct flights from Mumbai to the capital can save the airline about INR 1,21,000 per day, one way alone! Air India, with 12 direct flights, saves INR 1,32,000 one way, per day.

Aircraft with high navigation performance are allowed to fly the RNP routes. With higher accuracy, more airplanes can be squeezed on an airway. The “Q” routes allow aircraft to aircraft longitudinal separation of 50NM, while W13N allowed for a 10 minute separation, which translates to around 75NM. Theoretically, up to 13 airplanes may now fly on Q1, at any point of time, as compared to 9 on W13N. The capacity of the Indian Air Traffic System (ATS) has increased 44% on this route alone.

RNP and RNAV arrivals and departures are already in use, explained in another article which shall follow soon.

A Cockpit “flare” for “perspective”

03 Wednesday Oct 2012

Posted by theflyingengineer in Flight Safety, General Aviation Interest, Manufacturer, Operations

≈ 4 Comments

Tags

ATR 72, Cockpit, Constant Speed Propeller, Drag, Eye Level Indicator, Flare, Flare Technique, Q400, Seat Adjust, Seat Position Sight Gauge, Three Balls, Viewpoint

The Seat Position Sight Gauge on the ATR 72

The ATR 72-500 has its idiosyncrasies. In the cockpit is a “seat position sight gauge”, which are three small, coloured balls that allow a pilot to adjust his viewpoint to a position that ATR deems appropriate, allowing for a “correct view of instrument panels as well as runway environment”. The photo above shows the ATR 72 cockpit, with the sight gauge enlarged in the inset. If the first officer is to have his viewpoint right, he must adjust his seat height and position such that when looking at the three balls, the left white ball is obscured by the red centre ball.

Eye Level Indicator on the Q400

Interestingly, this gauge is not found in the Boeings, where the recommended method of adjusting the viewpoint is different. The ATR 72-500/600’s competitor, the Q400, however, has something similar, called the “eye level indicator”, as may be seen in the second photo. The Airbuses, not surprisingly, have a sight gauge similar to that found on the ATR.

Possibly one of the smartest first officers in India told me, after seeing me so diligently adjusting my P1 seat in an ATR 72-212A (500) to the correct viewpoint, that I was too high. Apparently, the seat position sight gauge does do its job well, but it isn’t something you’d want to level your eye with on an airplane like the ATR 72-500. Why? Visual perspective.

With the eyes adjusted, the view is good, and clean. But with the ATR 72, (and the Q400) one has to be very careful with the flare: the airplane’s fuselage is long and low, and a tail strike is easy. Another complication is the aircraft itself: having a constant speed propeller means that when you pull back on the power levers, the pitch angle of the propeller blades changes to “fine” (almost perpendicular to the direction of the airplane’s travel through the air), resulting in a significant increase in drag. If the flare is more than required, and the airplane balloons*, pulling back on the power levers is the last thing one would want to do, as the drag would make the aircraft drop to the runway like a stone! So one would add power to keep the airplane up, and this will eat up more runway: Messy indeed. And for him, with the ATR recommended viewpoint, comes the tendency to flare more than required.

*[The term “balloon” refers to a landing airplane that rises slightly before touching down. Ballooning is typically caused by excessive airspeed or excessive back pressure being applied to the flight controls by the pilot during the landing flare]

So what he does is to sit lower than the recommended view point: low enough to make him actually look up to see outside. This works well for him, and few others who have settled for this more comfortable, though not recommended, seating technique. Anything that works!

What can go wrong just because of an improper flare?

On 9^th May, 2004, N438AT, an ATR 72-212, during the approach to landing, the captain stated to the first officer (flying), “you better keep that nose down or get some power up because you’re gonna balloon.”. After the airplane crossed the runway threshold, the captain stated, “power in a little bit, don’t pull the nose up, don’t pull the nose up.” The captain then stated, “you’re ballooning,”. The airplane touched down with a vertical load of 1.3G, bounced into the air, touched down a second time, then bounced into the air with a nose up of 9°, climbed to 37 feet, and touched down a third time with a vertical load of 5Gs. After a fourth touchdown, the badly damaged airplane came to a stop outside the runway.

On 17^th September, 2005, D-ANFH, an ATR 72-212A, Just prior to touchdown, the co-pilot pitched the aircraft nose up to an attitude of 6.5º. The aircraft landed hard on the runway and bounced; in the course of the initial touchdown, the lower rear fuselage struck the runway surface.

On 23^rd May 2006, G-BWDA, an ATR 72-202, towards the conclusion of a brilliant approach, the first officer closed the power levers at 10ft and flared the aircraft. The airplane touched down, bounced into the air, and the attempt to arrest the sinking of the aircraft to the ground, pulled back on the control column, striking the tail.

And yes, I have also heard some of my friends say, “Oh damn, I forgot to flare!”

Shining the Green Laser: A detriment to flight safety.

20 Tuesday Mar 2012

Posted by theflyingengineer in Flight Safety, General Aviation Interest

≈ 1 Comment

Tags

Accidents, Aircrew, Aviation, distraction, Flight Safety, Green laser, Irresponsible use

A green laser can be picked up at any place for around Rs 800 (less than US$ 20). The beam is powerful, and the laser loses very little intensity in its propagation through air. Infact, the beam is so powerful that it can damage your retina, blinding you for life.

Irresponsible use of the powerful green laser is most observed by aircrew. A low flying aircraft on approach gives a sadistic thrill to those with a laser on the approach path: to shine the beam right at the cockpit. While this gives the man or woman, boy or girl on the ground a good few seconds of fun, the effects on the other side, up in the air, are anything but funny.

Firstly, the beam diverges slightly as it propagates through air. What appears as a pencil beam for the prankster is actually a huge green light for the pilot at a distance of around 5 kilometers (2.7NM) on approach. What has also been reported is the way in which the light diffuses when it strikes the windshield, having the effect of illuminating the flight deck, and distracting the flight crew.

Secondly, the intensity of the beam can either temporarily or permanently blind the pilot, especially on approach at night. If the cockpit floods with the green light and the pilot’s eye receives scattered light, vision will be temporarily affected, with the immediate consequence of losing sight of the runway and approach lights. This may lead to the aircraft going below the flight path, and impacting either terrain or buildings on approach. In case the laser beam directly hits the eyes of the pilot, the intensity can blind him or her for life, with immediate and long term consequences. The immediate consequence is the potential loss of control of the aircraft, threatening the lives of the 150+ passengers he is responsible for. The long term effect, if the airplane manages to be landed by the other crew member, is his inability to ever fly again as a pilot.

While admittedly this act is an of fun, and usually by the ignorant, helping spread the word can remove an unsolicited growing threat to flight safety.

Watch the FBI videos below to know more.

“Diving” into the A320: Dive Speeds

18 Sunday Mar 2012

Posted by theflyingengineer in Flight Safety, Operations

≈ 5 Comments

Tags

0.89, 381kts, A320, A380, Airbus, Airbus A380, Authority, Dive Speed, Expedite Descent, Flight Test, High, HSP, Mach, MD, MMO, Overspeed, Proection, Sidestick, SPeed, Structural Damage, VD, VD/MD, VMO, Warning

An apparently “lesser known” fact about the Airbus A320 is the dive speed, its significance, and the associated consequences.

A Flight Crew Bulletin detailing the dive speeds and other speeds above VMO/MMO. (Click to enlarge)

The dive speed is the absolute maximum speed above which the aircraft must not fly. Typically, to achieve this speed, the aircraft must enter a dive (steep descent), as the engines cannot produce sufficient thrust to overcome aerodynamic drag in level flight. At the dive speed, excessive aircraft vibrations develop which put the aircraft structural integrity at stake.

On the Airbus fly by wire aircraft, it is not possible to reach the dive speed, due to the flight envelope protections available in normal law. If the sidestick is maintained full forward, and the airspeed crosses VMO/MMO, the pitch nose-down authority smoothly reduces to zero at approximately VMO +16 / MMO + 0.04. This however, does not guarantee the airspeed stabilizing at this speed.

If MMO + 0.04 / VMO + 20kts is reached or exceeded, then a structural inspection is necessary. Beyond MD (= MMO+0.07) / VD (= VMO + 31kts) (A320 family), structural disintegration can occur.

Here are the speeds for the A320, in Mach number and Kts. The lesser value must always be respected, at all times:

Graphical representation of the speeds, their significance & consequences. HSP is High Speed protection range.

Dive Speeds:

MD/VD = M0.89/381kts

Maximum Operating Speeds:

MMO/VMO = M0.82/350kts.

Expedite Descent (as on FCU, if available)

M0.8/340kts

The graphical representation of speeds above VMO/MMO, on the left (made by The Flying Engineer), gives you a clearer picture of the speeds, their significance for the FBW system, and the consequences.

To understand the seriousness of the VD/MD, take a look at the video below, which involves the VD/MD testing of the Airbus A380. The MD for the A380 is Mach 0.96, and the test crew dread taking the airplane that far.