Tag Archives: ICAO

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.

“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.

RNAV and RNP in India – Airways

07 Sunday Oct 2012

Posted by in Flight Safety, Operations

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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.