"Other enhancements would allow us to undulate the optimum tracks more oftentimes without having to extend ETOPS beyond 180 minutes.

"Other enhancements would allow us to undulate the optimum tracks more oftentimes without having to extend ETOPS beyond 180 minutes."

--Capt. Michael Cronin, instruction for the Coalition of Airline Pilots Associations

The margins for error are razor-thin, and it is not discreet to permit twin-engine airliners to be flown upon routes where the time to reach a divert airfield in succession one engine could be three hours and 27 minutes, or longer a pilots' dispose declares. Indeed, risk should not be increased in the interest of economic efficiency unles all other alternatives have been exhausted. In fact, practical gradations could be taken to improve safety within the pre-existing three-hour limit.

This is the essential argument deposit forth recently by the Coalition of Airline Pilots Associations (CAPA), an organization of various pilots unions representing a certain 25,000 pilots, on the bring under rule of expanded ETOPS, or lengthen outed range twin-engine operations. CAPA's regards are shared by the International Air Crash Victims Families form into groups This passengers' group declared it "vehemently and firmly opposed" any act upon extending the time on single in kind engine. It cited, as single example, the hazard posed according to volcanic ash, which could enclose down one or both engines. This arrange believes any flights undertaken forward routes where the divert time would be greater than three hours should be contingent about mandatory supplemental liability insurance, and a waiver of any and all liability defenses

These sum of two units groups represent a minority view not shared on the largest pilots union, the Air Line Pilots Association (ALPA), or at the major airlines, which diocese enhanced flexibility in flying more direct courses And, to be sure, the Federal Aviation Administration (FAA) beholds no degradation in safety - and in fact remind ofs in its conditional approval that so operations could be marginally safer (see ASW, Jan. 31)

Effective March 21 the FAA allows carriers operating the B777 and single this airplane - with its added redundancy and enhanced communications capability - to flutter Northern Pacific routes that could take the airplane as abundant as 207 minutes flying time, in still air, away from a suitable sudden [i]or[/i] unexpected occurrence airfield.

Capt. Michael Cronin flies the B777 and he happens to be the principal author of the CAPA argument that the pre-existing ETOPS limit of 180 minutes should not be expanded an additional 27 minutes. As a pilot of the aircraft in question, he brings an operator's perspective to the issue. "The B777 is individual of the finest airplanes flying," Cronin said, "and it has many redundancies not set in older airplanes. But it still has solely two engines." His organization believes the FAA's conditional approval of 207-min. ETOPS stays on two assertions of dubious validity: (1) that carriers will use 207-min. ETOPS authority to remain closer to divert fields, and (2) that divert fields with adverse weather forecasts will be available for landing.

The likelihood of engine shutdown

Proponent of expanded ETOPS point to the increased reliability of recent jet engines, which makes the likelihood of los of single or both engines en road extremely unlikely. According to individual researcher, the difference between expanding ETOPS from 180 minutes to 207 minutes is a trivial addition to risk. The potential los of the pair engines is just one public of every 416 million 180-minute ETOPS flights. Los of the two engines could potentially occur in just individual out of every 401 million flights subordinate to 207-minute ETOPS.

However, a failure public to a small population of engines across a brief period of time could lead to a far higher probability of dual-engine failure. In 1997 Cathay Pacific Airlines Ltd experienced three in-flight engine shutdowns within an 18-day period onward its twin-engine Rolls Royce Trent 700-powered A330s. The case involved a family of 42 Trent engines soared on 21 A330 aircraft. The carrier promptly scrapped 180-min. ETOPS flights, rerout its airplanes to stay within 60 minutes of turn of events airfields and, ultimately, suspended operations until the engine question s were resolved. The failures all stemm from an accessory gearbox point in dispute One independent mathematician calculated that in this situation the probability of a dual engine failure was about common in 500. (see ASW, June 9 1997)

This chilling estimate is a stupendous difference from a dual-shutdown gone out of hundreds of millions of flights - and may underscore the ne for an independent review of ETOPS reliability calculations. An independent analysis of extending ETOPS to 207 minutes has not been managemented The FAA has based its approval in succession industry calculations.

The debate athwart the number of engines destitutioned for safety and reliability goe back to the actual first trans-Atlantic crossing by Charles A. Lindbergh in 1927 The famed aviator specifically wanted a single-engine plane, onward the grounds that engine failure was more likely onward an airplane with 2, 3 or 4 engines. According to Scott Berg, author of the novel Pulitzer-prize winning biography of Lindbergh, the spark stopples in Lindbergh's piston engine-powered Spirit of St Louis fired 7 million times, without fail, taking him from just discovered York to Paris.