Category Archives: Aviation

Is the Indian ‘Middle Class’ of 300 Million ready to fly?

05 Thursday Nov 2015

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NCAP 2015 Regional Aviation India

Everyone today looks upto India as the next destination for growth. The Ministry of Civil Aviation, in its draft National Civil Aviation Policy, has captured the attention of everyone with the claim of a large middle class population, and the promise of certain reforms that should may better the ease of doing business.

We appreciate what the Ministry has done, is doing, and will do. But certain claims must be taken with a pinch of salt, must be questioned, and analysed, just to prevent over-optimism and to make room for realism. Like for example:

  1. India is a 300 million strong population of middle class persons. The Ministry targets each of these 300 million to fly atleast once in their life. Pertinent questions: What is the definition of middle class? What subset can really afford air travel? These questions are important to prevent overcapacity in the Indian market based on optimism.
  2. India targets 300 million domestic ticketing by 2022. That means, calendar year (CY) 2021 must end with 300 million domestic passengers in a single year. India will end CY 2015 with 80 million domestic passengers. What is the compound annual growth rate (CAGR) required to touch 300 million in CY 2021? Is this CAGR too high to achive? What do market leaders like Airbus say?

Today, we focus on these two issues, which form part of the Ministry’s vision, and we see if this is achievable. Our views on the Regional Connectivity Scheme and the 5/20 are ready, which we hope to release tomorrow. We will also be commenting on Scheduled Commuter Airlines (SCA) and Safety, and lightly touch upon Aeronautical ‘Make in India’, Aviation Education & Skill Development, and Air Navigation Services.

To read about the first two issues, please click here.

DGCA responds to The Flying Engineer

29 Saturday Nov 2014

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On 14th November 2014, the Flying Engineer had pointed out discrepancies between airline’s reported data and DGCA published data. The Director of Statistics at the DGCA – R Savithri – responded with the following statement:

“The issue of mismatch between the passenger numbers published under passengers carried as per the ICAO Form ‘A’ for the said months and the passenger numbers published on page 14 of Domestic Traffic Reports had already been noticed by DGCA. ln order to resolve this problem a meeting was held in the month July and it was found that the main reason of the mismatch lies in the fact that the airlines were not including the number of passengers carried on the domestic leg of the international routes while reporting data as per Form ‘A’ of ICAO. While passengers carried published on page 14 of Domestic Traffic Reports includes this number. There is still a small difference in the number of passengers carried shown under the two tabs from the month of August onwards. This difference still persists due to the fact that the passengers carried published on page14 of Domestic Traffic Reports also includes charter or non scheduled flights data which is not a requirement for ICAO Form ‘A’“.

The implications of this is that the market share of various airlines, as calculated and published by the DGCA, is not truly indicative of an airline’s market share. The variations are, admittedly, small.

The director also clearly stated that the hours under ‘Aircraft flown’ correspond to Block Hours. Some airlines, in an attempt to make their aircraft utilization numbers appear good, had stated that those were flight hours. The director clarified that ‘no airline is reporting flight hours instead of block hours’.

The Flying Engineer has also learnt that the statistics for AirAsia India and Air Costa will be available in the statistics publication January 2015 onwards. Air Costa’s data has been included in the Total Traffic Statistics of Scheduled lndian Carriers for the month of October, which was published a few days ago.

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

09 Thursday Oct 2014

Posted by in Flight Safety

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UAS_Begumpet_IndiaAviation_2014The 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

170cc_prophang_airshowSince 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 in Airline, Aviation, Flight Safety, Human Factors, Incidents and Accidents, Training

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ATC twr 2The 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.

TATA-SIA Airline’s first A320 gets ready

11 Friday Jul 2014

Posted by in General Aviation Interest, Manufacturer, Operations, Technical

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A320_family_takeoff

TATA-SIA’s A320-232SL (SL=sharklets), was spotted flying for the first time at Toulouse, France yesterday. The aircraft was flown with a test registration F-WWDT, and the airframe is serial number 6223.

The aircraft is to be registered as VT-TTB. The aircraft will next fly to Hamburg where it will have its cabin fitted in accordance with TATA-SIA’s preferences.

The aircraft is expected in Delhi, India by August 15th, but no later than August 20th.

The airline received its no objection certificate (NOC) from the ministry on April 2nd 2014, and applied for an air operator permit (AOP) on 22nd April 2014. On 9th July 2014, the DGCA decided to consider the AOP application of TATA-SIA, after inviting and reviewing objections and suggestions from the public.

Judging by the pace of developments and clearances at the airline, the AOP is expected by the first half of September. Considering that the Delhi High Court today adjourned the hearing of petitions filed by the Federation of Indian Airlines (FIA) and Subramanian Swamy against TATA-SIA and AirAsia India to September 12th, TATA-SIA may secure its AOP before the court hearing.

Once the AOP is secured, the airline may open for sales in September, and begin operations by end September / early October, subject to timely clearance of flight schedules by the DGCA.

Choice of Power.

Although TATAs have a stake in both TATA-SIA and AirAsia India, the engine chosen by the full service airline is the IAE V2527-A5, unlike the CFM56-5B6 flown by AirAsia. This particular IAE engine is similar to what IndiGo uses on its Airbus A320 aircraft, and has a higher thrust but lower bypass ratio when compared to the CFM56-5B6. As a result, the IAE engines are noisier.

Parameter

 CFM56-5B6 IAE V2527-A5

Take off Thrust

 104.5kN 110.3kN
Bypass Ratio 5.9:1 4.8:1
Noise* Lower Baseline

*Based on FAA data. Quantified comparison omitted here as it’s too exhaustive.

A320_6E_IAV2527_A5

IAE V2527-A5 on an IndiGo A320-232SL

Pratt and Whitney holds majority stake in the IAE venture, which was originally formed between Pratt and Whitney, Rolls Royce, MTU Aero Engines and Japanese Aero Engine Corp now has Pratt and Whitney as the major stakeholder when the United Technologies Corporation engine unit bought out Rolls Royce’s stake in October 2011.

TATA-SIA’s choice of engine was very natural. Singapore Airlines flies Boeing 777s, A380s, and A330s-all powered by Rolls Royce Engines. Singapore Airlines’ subsidiary-Silk Air-flies A320 and A319 aircraft fitted with IAE engines. Tigerair, in which Singapore Airlines has a stake, flies A320s and A319s with IAE engines.

AirAsia’s fleet mostly comprises of the A320-216 (CFM56-5B6 powered).

According to Amit Singh, Director Flight Operations at AirAsia India, the low thrust of the 5B6 translates to maintenance savings. Worldwide, CFM engines have a reputation for reliability and robustness, reportedly better than IAE’s. The CFMs are reported to offer better economics on the A320 and A319.

Although CFM has more than 55% of the classic engine market that powers the A320 aircraft, it has a lower market share in Asia Pacific. In India, presently, 93 Airbus A320 family aircraft are powered by IAE Engines, while 66 are powered by CFM engines. Of the 93 IAE powered A320 aircraft, 78 comprise IndiGo’s fleet.

Edit: Thrust ratings changed to reflect take off thrust as published by EASA.

Autoflight now available: PAT

09 Monday Jun 2014

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LOGO_1280Project Airbus Tech (PAT) is pleased to announce that chapter ATA 22 / autoflight is now available! Covering this chapter – close to 150 questions, was a huge task, but A320 rated and soon to be released line pilot Sushank Gupta has done a great job answering each and every question. “This one was a monster chapter, very extensive and really in-depth. Phew !!”.

CLICK HERE for Autoflight.

“Fuel Emergency” & Fuel Quantity: Getting it right

27 Sunday Apr 2014

Posted by in Flight Safety, Operations, Technical

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9W_PushbackThis 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.

Air Costa gets approval to fly the Embraer E190s

28 Friday Mar 2014

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E190 Air Costa

Air Costa yesterday received the approval from the DCGA to fly the Embraer E190s. Air Costa is the first airline in the history of Indian aviation to operate Embraer E190s. The airline started operations in October 2013 with two Embraer E170s.

The two Embraer ERJ E190s, with manufacturer serial numbers 593 and 608, registered VT-LBR, VT-LVR respectively, were delivered to Air Costa towards the second half of December 2013, and are leased from GECAS. However, the approval to fly the E190s arrived only 3 months later, due to exhaustive DGCA paperwork, some of which related to getting the aircraft type approved in India. The airplanes have been parked at Hyderabad-Shamshabad’s Rajiv Gandhi International (ICAO: VOHS IATA: HYD).

The two Embraer E190s are expected to be deployed into commercial service in the first week of April, and will fly the longer routes in the approved summer schedule. Since the ERJ 190’s license endorsement, as recognized by the DGCA, is “EMB170”, and common with the ERJ 170, pilots in the airline can fly both aircraft variants.

The E190s will be based at Chennai, and will be deployed on the following sectors: Chennai-Ahmadabad, Ahmadabad-Bangalore, Bangalore-Jaipur, Jaipur-Hyderabad, Hyderabad-Chennai, Chennai-Bangalore, Bangalore-Vishakhapatnam, Vishakhapatnam – Hyderabad.

Each aircraft will start operations at 0600hrs IST, and fly till 2340hrs IST, accumulating a total of 29 block hours per day over 18 flights, representing 56% of the entire fleet’s utilization. The E190s will be utilized approximately 30% more than the E170.

The Embraer E190s are an all-economy four abreast-single aisle cabin, with 112 seats laid out over 28 rows, with a 29/30-inch seat pitch (some seats will have a comfortable pitch of 30 inches, while the others will have 29 inches). Each of the seats are as wide as 18.25 inches, armrest-armrest, which is a good 1.25inches wider (and more comfortable) than the seats on SpiceJet’s Boeing 737s, and IndiGo, GoAir and Air Asia India’s Airbus A320s, which are all 17 inches wide. In addition, there are no middle seats: only either window or aisle, making the overall experience very comfortable. This comfort will make the airline’s product a preferred one, among regional airlines, today.

The 112 seat E-190 has 62% the capacity of an Airbus A320, which the airline feels is the right capacity for the markets they serve today. Another 4 E190s are expected to join the fleet this year.

Air Costa has been flying the E-170s with load factors greater than 70%.

A Slew of single aisle firsts in March

26 Wednesday Mar 2014

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737_A320NEO_E175Perf

Three jetliner manufacturers, Airbus, Boeing and Embraer, in alphabetical order, rolled out single aisle firsts in March this year.

It started on March 12th, when Embraer rolled out the first production E175 with fuel burn improvements. New winglets, and fuselage wide aerodynamic “cleanups”, and system optimizations have bettered fuel consumption by 6.4%: a good 1.4% better than the technical team had expected to see in fuel savings, on a “typical flight”, which, according to The Flying Engineer estimates, are in the 500-1000NM region. This 6.4% fuel burn reduction is close to double the figure Airbus achieved with its A320 when it strapped on the winglets it calls Sharklets: between 3-4%, and more than 3 times what Boeing achieved with its 737NG when it rolled out the 737 Performance Improvement Package (PIP) in 2012: 2%.

On March 17th, Airbus announced the final assembly of its A320NEO: the next landmark in mainline single aisle airplanes. The A320NEO will be the first single aisle airplane in its class to enter service, with a new type of engine in this thrust class: the Geared Turbofan Engine. The GTF is expected to set the A320NEO apart from the 737MAX; the latter is expected to fly with the CFM LEAP-1B engine that runs hotter, leaving little room for any engine growth in the future.

On March 20, Boeing rolled out the first Boeing 737NG at increased production rate: 42 airplanes a month, matching what Airbus had achieved almost a year ago: which then was the highest commercial aircraft monthly production rate ever. The interesting feat here is that Boeing achieves this at a single facility, while Airbus gets its 42 airplanes a month at its three final assembly lines: Toulouse, Hamburg, and Tianjin.

As for Bombardier, which is going through a very difficult period, the First CS300: the only aircraft variant in the CSeries program that is relevant today and has garnered much attention from customers, almost twice the firm orders as the shorter variant, the CS100, is in final assembly and the systems are being installed. First flight of the CS300 is expected soon, and the entry into service of the CS300 is expected 6 months after the CS100, the latter slated for the second half of 2015, with the hope that no further program delays are announced.

Airbus A320NEO Enters FAL (MSN6101)

19 Wednesday Mar 2014

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A320 MSN 6101 FAL

Airbus’ first A320NEO, MSN 6101 (A320-271N) has entered the final assembly line (FAL) at Toulouse, marking yet another milestone in the A320NEO program. The forward fuselage, which arrived from St. Nazaire in France, and the aft fuselage, which arrived from Hamburg in Germany, were mated at the FAL, marking the start of the final assembly.

The next stage is the joining of the wing to the fuselage. Overall, it takes about one month to complete the final assembly of an A320 Family aircraft.

The A320 program crossed a major milestone in November 2013, when the assembly of the first major component- the engine pylon- took place.

First flight is expected in the Autumn of 2014, almost 4 years after the program was launched in December 2010. Airbus took the landmark decision of re-engining the A320 Family after sensing imminent competition from Bombardier’s C-Series airplanes.

Airbus will retain 95% airframe commonality with the present A320, offering the benefit of high dispatch reliability associated with a mature airframe. Airbus has also effected incremental changes to its traditional Airbus A320, thereby eliminating the risks associated with too many modifications in one shot.

In the November of 2011, Airbus flew the first A320 with the version of the sharklets that are now seen on all new production Airbus A320 airplanes, first sharklet-equipped A320 being MSN 5428 delivered in December 2012. The sharklets, which will feature on the A320NEO as well, introduce fuel savings of upto 4% on long flights. Preliminary wing strengthening to handle the aerodynamic loads introduced by the sharklets, and airplane-wide weight reduction to offset the weight due to the strengthening have already been effected.

NEO’s difference from today’s in-production A320 aircraft is the further strengthening of the wing and fuselage to handle the loads associated with the heavier and larger New Engine Option (NEO): The Pratt and Whitney PW1100G and the CFM LEAP-1A. The new more efficient engine together with the sharklets realize a 15% fuel savings on 800nm route lengths, and up to 16%+ on the longer routes, compared to non-sharklet fitted Airbus A320 aircraft.

The Pratt and Whitney Geared Turbofan Engine PW1100G series for the A320, took to the skies in May 2013, on a Pratt and Whitney Boeing 747SP flying test bed.

Changes to the A320 are minimal and the least among other airplanes which are being re-engined and  modified to a larger extent, such as the Boeing 737MAX and the Embraer Second Generation E-Jets E2. Historically, all new airplane programs have been met with significant dispatch reliability issues related to technical or maintenance issues associated with an immature airframe. The A320NEO program has the least changes, followed by the MAX and E2 program. The all-new Bombardier C-Series introduces many firsts for Bombardier, making it the program that may likely have the most number of issues, initially atleast: a reason which explains the low number of firm orders: 201, despite having 3 flying airplanes in the test campaign.

 In contrast, the Embraer E-Jet E2 program, which airplanes are still “paper” (conceptual), has 200 firm orders. The Boeing 737MAX has 1,807 firm orders and the Airbus A320NEO program has firm orders for 2,667 airplanes.

Least changes with benefits where it matters to an already proven and mature airframe, incremental modifications, early introduction into service (Q4 2015), a dual engine source (all other new/re-engine programs have only one engine supplier), keeping up program development schedule, and the smallest training impact have contributed in large to the sales success of the program.

IndiGo has an order for 180 Airbus A320NEO Family aircraft, which include the A320NEO and A321 NEO. Go Air has 72 airplanes on order, and Air Asia 264 A320NEOs on order. Both IndiGo and GoAir’s A320NEOs will be powered by the Pratt & Whitney PW1100G. IndiGo operates the IAE engines, of which Pratt and Whitney is a part. Go Air which flies CFM powered A320 aircraft, has switched engine suppliers, to Pratt and Whitney. The PW1100G engines offer two advantages: Room for growth, and availability sooner than the CFM LEAP-1A Engines. Air Asia, which flies CFM powered A320s, has opted for the CFM LEAP-1A to power its NEOs.

FAA Downgrades India to Category 2

31 Friday Jan 2014

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Downgrade_crash

As released by the FAA:

FAAThe 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.

Chapter ATA 70: Engines: Project Airbus Tech Update

24 Friday Jan 2014

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LOGO_1280Project Airbus Tech is pleased to announce the addition of the chapter on Engines (IAE V2500 as in IndiGo’s fleet). These questions throw immense light into an Airbus A320’s engines, engine systems, limitations, and much much more!

Click HERE to access the question & answer bank, and scroll down to 19: Powerplant: ATA 70!

General Aviation: Flight Safety Beyond Regulations

21 Tuesday Jan 2014

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

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VT_DCE

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_Garmin_Cessna

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.

G1000_MFD_with_without_SD

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

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G1000_SBAS03_Map

Gagan LogoWith 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) G1000_SBAS01communication/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.

G1000_SBAS02The 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.

SBAS CrudeThe “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

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Cochin INstrument Approach Rwy27Some 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.

777X’s Trans-Sonic & Sub-Sonic Wind Tunnel Testing Underway

16 Thursday Jan 2014

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Left: Subsonic wind tunnel testing at QinetiQ's facility in Farnborough, U.K, Right: Trans-sonic wind tunnel testing at Boeing's Transonic Wind Tunnel in Seattle

Left: Subsonic wind tunnel testing at QinetiQ’s facility in Farnborough, U.K, Right: Trans-sonic wind tunnel testing at Boeing’s Transonic Wind Tunnel in Seattle

Boeing announced that testing has begun at the Boeing Transonic Wind Tunnel in Seattle to further validate 777X high-speed performance projections. Data from the high-speed tests will help engineers with the configuration development of the airplane, validate computational fluid dynamics (CFD) predictions and support preliminary loads cycle development.

Subsonic wind tunnel testing on the 777X started on Dec. 5, 2013 at QinetiQ’s test facility in Farnborough, U.K., to test the airplane models’ performance at low speeds such as those experienced at takeoff and landing, and at different non-clean configurations, notably with the high lift devices such as flaps and slats.

“We are on track to complete our top-level design in 2014 and reach firm configuration in 2015,”, Terry Beezhold, vice president and chief project engineer of the 777X program, said, back in Dec 2013. “Wind tunnel testing will validate our performance models and generate a vast amount of data that our engineering teams will use to design the airplane in this phase of development.”

The Boeing 777X program, which includes the 777-8X and 777-9X aircraft, is yet to be formally christened.

Understanding the Ultimate Load-Wing test: A350

14 Tuesday Jan 2014

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A350_Ultimate_Load_Wing_Test

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

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

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 13th Jan 2014 at ~00:11 UTC (12th 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 Track Deviation

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

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

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).

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.

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

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

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GPS Satellite Present 2145 09 JAN 2014

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.

GPS_Receiver_Satellites_and Signal

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 2146 IST 09 JAN 2014

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.

GPS_Position

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.