Debate about US proposals for long-range aircraft operations could be reignited by the dispute over the three-engine 747 flight

A vigorous operations policy debate raging a year ago seems to have gone to ground. This is the attempt by the US Federal Aviation Administration and its Aviation Rulemaking Advisory Committee (ARAC) to redefine completely what the term ETOPS means.

Remember ETOPS? Originally it stood for extended-range twin-engine operations, and concerned the rules defining how far a twin-engined aircraft's planned track may stray from a usable diversion airport. As engines became more reliable and airlines operating big twins like the Airbus A300 and the Boeing 767 sought to fly them across oceans and wilderness, aviation authorities on both sides of the Atlantic allowed the flying time from diversion to rise gradually from 60min to 180min.

The incident in which a British Airways Boeing 747-400 captain elected to continue a Los Angeles-London flight despite having to shut down an engine just after take-off is going to add fuel to the debate about redefining ETOPS. That would be no bad thing. The more open this debate, the better for the industry and consumers alike, because just as the airlines would prefer to be left alone to decide what is operationally feasible on behalf of their customers without press and public input, so the FAA would like its current attempt to rewrite the ETOPS rules to be carried out without too much scrutiny from outside the US industry.

Last year the FAA/ARAC rulemaking proposal for a completely redefined ETOPS opened for comment to a storm of protest from everywhere except the domestic USA. It proposed that the ETOPS time-from-diversion should be extended to 240min – and possibly further – for twins that have appropriate systems redundancy and fire protection. The new rule, however, would also apply the same restrictions to trijets and quads – for the first time. Meanwhile, older trijets and quads would be given a period of grace in which to continue to enjoy their unrestricted status. But when their "grandfather rights" died because they did not meet some of the more demanding systems requirements proposed as part of the ETOPS formula, they would lose their privileges and not be able to operate some of the services for which younger twins could be cleared.

All the issues surrounding the debate on what the FAA calls ETOPS and the European Joint Aviation Authorities calls LROPS – long-range operations – concern systems redundancy, drift-down height following engine unit loss, and the ability of an aircraft and its crew to deal with whatever could plausibly happen on board during a flight, so that diversion is not required. This is the basis on which the BA crew decided to continue with only three engines operating. They still had powerplant redundancy and would never be more than about 60min from an emergency diversion airport if they lost another engine. A twin, on the other hand, with one engine shut down would have had no remaining powerplant redundancy, so the crew's choices would have been much more limited and thus much easier.

So where does this event take the debate? The ETOPS/LROPS issues are still defined, ultimately, by how long an aircraft should be allowed to continue with reduced redundancy in one or more of its critical systems. In extremis – the theoretical LROPS case – that could mean anything up to the length of time it takes for the aircraft to cover its maximum range. But is that what the regulators would really like to see? Under the FAA's proposed ETOPS vision, would a Boeing 777 captain be allowed to continue on one engine from Los Angeles to London as the BA 747-400 has just done? The FAA says a US operator of a quad would have been expected to land reasonably quickly if an engine had failed. The UK Civil Aviation Authority sees no reason – so far – to change its advice to operators.

Surely the debate is about the basics – it is about what kind of journey an airline can legally plan for a given type of aircraft. Does it have sufficient critical systems redundancy to fly over large oceans or huge wildernesses? Should it enter the "unfriendly" sector of its journey if the aircraft's critical systems redundancy level has already been degraded? Or is the engine and systems redundancy sufficient to enable the aircraft to remain safe if a critical systems fault occurs once it has already entered a part of its journey, where quick diversion is impossible or a major risk in its own right?

The industry and the regulators have the expertise to decide what operational limits should be set, but public scrutiny is essential because it concentrates minds by reminding experts on whose behalf they carry out their work.

Source: Flight International