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Old 14th Sep 2000, 01:12
  #1 (permalink)  
US Marine
Posts: n/a

Where can I find info on ETOPS? Ex-military, so don't normally care about this but interview beckons.

in particular, overview, suitable diversion requirements, what are the ETOPS categories, how are a/c certified for 180min ETOPS

Any help, appreciated
Old 14th Sep 2000, 06:44
  #2 (permalink)  
Posts: n/a

A little paper I wrote re: ETOPS back in College (summer 97). Might be of some use.

Q Trans-Atlantic ETOPS
The routes between North America and Europe are the most heavily traveled international airline routes in the world. During the 1960's, 1970's, and 1980's, large three and four engine aircraft were typically used, e.g. DC-10, L1011, B707, DC-8, and B747. However, in the late 1970's Boeing and Airbus launched long range twin-engine aircraft which were capable of traversing the Atlantic, e.g. B757, B767, and A310. After gaining experience operating these large twins in domestic operations, under FAR 121.161 (two-engine airplane operating within 60 minutes of a suitable alternate, with one-engine inoperative, in no wind conditions), airlines requested to be granted a waiver to 121.161, and operate more than 60 minutes from a suitable alternate. ICAO/FAA/JAA studied the proposal and after confirming the increased reliability of new twin-engine aircraft, ETOPS / ER-OPS (Extended Range Operations with Twin-Engine Airplanes) was launched.
The first official ETOPS flight occurred on March 26, 1984 from Montreal, Canada to Tel Aviv, Israel utilizing a Boeing 767-200ER (Extended Range). Regularly scheduled ETOPS flights began in February 1985 using the B767 at TWA and El Al Airlines. Also joining the ETOPS ranks were other international airlines using the B767, including Aeroflot, Air Canada, Air France, American, British Airways, Canadian Airlines International, Delta, LOT, MALEV, SAS, and US Airways. The A310 was also approved for the 121.161 waiver for use at Pan Am, Austrian Airlines, Czech Airlines, Swissair, TAP-Air Portugal, and TAROM. The most recent addition to the ETOPS fleet is the B757-200, which is approved for Trans-Atlantic flights at Continental, TWA, and United.

Q ETOPS Requirements
To be authorized to operate ETOPS flights over the North Atlantic, airlines must modify the airframe and propulsion systems with various backup systems, e.g. hydraulic motor generator, floatation devices, dual fuel crossfeeds, additional cargo compartment fire bottles, and standby navigation systems. These aircraft modifications, coupled with increased maintenance requirements, make ETOPS operations extremely reliable.
An air carrier initially seeking ETOPS approval must apply for a waiver to FAR 121.161 which grants privileges in the Operations Specifications as issued by the POI (Principle Operations Inspector). Approval must also be granted from the PMI (Principle Maintenance Inspector), Principle Airworthiness Inspector, and the PAI (Principle Avionics Inspector). The approval for ETOPS is granted according to Advisory Circular AC 120-42A, in cautious increments to allow airlines to build in-service experience and expertise in operating over extended-routes with a particular airframe/engine combination. The airline is normally granted ETOPS in increments of 75 minutes, 120 minutes, and 180 minutes. These maximum diversion times are from a suitable alternate at the one-engine cruise speed (during standard conditions, in still air conditions).
As listed in AC 120-42A, an airline seeking ETOPS approval must first show that it is capable of operating safely for one year under the 75 minute ETOPS rule. During this period, the airline must operate within 75 minutes of suitable alternates while over the North Atlantic. After 12 months of 75 minute ETOPS, 120 minute ETOPS may be granted if the airframe-engine combination have performed safely under ETOPS, e.g. maximum IFSD (in-flight shutdown rate) of .05/1000 hours (with continuous improvement towards a .02/1000 hours, IFSD). The 12-month trial period may be reduced if the air carrier has pervious experience operating the same airframe or engine type in domestic operations. To gain approval for 180 minutes ETOPS, the air carrier must operate the extended range fleet for at least one year in ER-OPS, with an IFSD of approximately .02/1000 hours. The prescribed IFSD should be maintained, if the IFSD should increase, the POI would reevaluate the air carrier's ability to operate safely under ETOPS.

Q ETOPS Dispatching
Special considerations must be followed in order to launch an aircraft along a route with enough options and fuel, to safely complete the flight as dispatched or make a diversion (in the case of an engine failure). MEL (Minimum Equipment Lists) for ETOPS certified aircraft must be developed which assure that the aircraft has adequate redundancy to continually perform on extended range routes. These back-up systems should include: electrical, hydraulic, pneumatic, flight instruments, fuel, flight control, ice protection, engine start and ignition, propulsion system instruments, navigation, communications, and auxiliary power-units (APU).
The fuel/oil supply required on ETOPS flights must be calculated according to FAR 121 regulations, which accounts for forecasted weather along the intended route (and on diversion routes at one-engine inoperative cruise levels). On ETOPS flights, the departure fuel loading required is the largest amount of the following: Non-ETOPS flight (normal fuel reserves), ETPC scenario -- simultaneous engine and pressurization failure at the ETP (Equal Time Point) between ETOPS alternates (critical fuel scenario).
A critical fuel scenario is used to determine the maximum amount of fuel needed to complete a diversion to an ETOPS alternate at the ETP. The scenario assumes failure of one-engine and the pressurization system at the ETP and immediate drift-down to 10,000 feet is required. To create an added safety margin some fuel contingencies are required: 5% fuel for weather forecasting errors, CDL items, 15% fuel burn for anti-icing equipment, and additional fuel burn for APU use, if an APU is the required power source in diversion scenario (e.g. 330 lb./hr, 767-300ER).

Q Operations Specifications

In order to operate twin-engine aircraft legally over the NAT (North Atlantic) air carriers must have specific approval from their POI, documented in the Operations Specifications (Ops Specs).
To operate in areas without reliable ground-based navaids an air carrier must have authorization for navigation using long-range navigation systems (INS- Inertial Reference System or INS - Inertial Navigation System). This is granted in paragraph B36 (Class II navigation using long-range navigation systems or flight navigator), which allows those flights unable to attain an accurate fix from a ground based Navaid (at least once per hour) to use long-range navigation systems. The aircraft and navigation system must be listed in the Ops Specs, paragraph B36.
Example: Boeing 767-200 / Dual Sperry INS
Operations within the NAT/MNPS (NORTH ATLANTIC MINIMUM NAVIGATION PERFORMANCE SPECIFICATION AIRSPACE) require that all aircraft must be approved in paragraph B39, listing approved aircraft make/model and long-range navigation systems.
Example: Boeing 757-200 / Dual Sperry FMS/IRS
To operate twin-engine aircraft within the NAT (within 60 minutes of an alternate), authorization for B41 must be granted (|NAT/OPS), the aircraft make/model must be listed in the Ops Specs.
Example: Boeing 757-200 / N123US
For ETOPS (ER-OPS) approval paragraph B42 must be granted. B42 pertains to extended-range operations with twin-engine airplanes under part 121. To be granted B42, the POI must confirm that the carrier complies with AC 120-42 (for ETOPS operations in excess of 75 minutes). Aircraft make/model/series and registration numbers must be recorded, as well as the maximum ETOPS diversion time authorized.
Example: Boeing 757-200 / N123US / 180 minutes
The alternate requirement for ETOPS takes on special importance, as the choice of available alternates while crossing the North Atlantic is minimal. It is therefore necessary to choose those alternate airports, which provide the necessary safety equipment (FAR 139) and landing approach aids to assure a successful diversion. The importance of a "safe" suitable alternate for a diversion will be required in an emergency, with one-engine failure and possible other malfunctions (pressurization). The approved ETOPS alternates must be listed in the Ops Specs paragraph B42.

The following alternate minimums apply:
Single Precision approach: Ceiling of 600 feet, visibility 2 miles or ceiling 400 feet and visibility 1 mile above the lowest authorized landing minima; whichever is higher.
Two or more precision approach runways: Ceiling of 400 feet, visibility of 1 mile or ceiling of 200 feet and visibility 1/2 mile above the lowest minima; whichever is higher.
Non-precision approach (es): Ceiling 800 feet and visibility 2 miles or ceiling 400 feet 1 mile above lowest minima.
Example: Gander, CYQX, ETOPS Alternate Minima = 400 -1

Final approval must be authorized in paragraph 50 (authorized areas of enroute operations, limitations, and provisions) to allow the air carrier to operate in this region. In addition, special requirements and limitations may apply, to ensure a safe flying environment.
Example: The North Atlantic Ocean, including NAT/MNPS airspace. 767 ETOPS operations: MEA for planned routes 27,500 feet, MEA for diversion route - 10,000 feet.

Q ETOPS future

ETOPS has gained wide appeal among all airlines as it allows routes previously requiring larger aircraft to be operated with extended-range two-engine aircraft. Today the efficiencies of new aircraft and engines has allowed twin engine aircraft to achieve the range of previous jumbo-jets, giving airlines a competitive advantage on thin routes. The latest landmark in ETOPS was achieved by the Boeing 777, which was authorized for 180 minute ETOPS upon certification. The longest ETOPS route operated today is from Guangzhou, China and Los Angeles using the B777-200IGW (GE90-90B).

1. Broderick, A. J. (1988). Extended range operation with two-engine airplanes (Advisory Circular 120-42A, Federal Aviation Administration). Washington, D. C.: U.S. Government Printing Office.

2. Hughes, D. (1992, April). ETOPS proves a success on the North Atlantic routes. Aviation Week and Space Technology, pp. 44-52.

3. Lusk, B. (1997, May). By air over the North Atlantic. Airways, pp. 27-29.

4. Marriott, L. (1991). From the flight deck, Britannia 767, Prestwick - Orlando. England: Ian Allan Ltd.

5. Padilla, C. (1996). Optimizing jet transport efficiency. USA: McGraw-Hill.

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