Basler turbo-prop and ski rendering of a DC-3, Mawson: AAD photo by Chris Wilson

The esoteric story of the past week has to be Airbus seeking to certify its new super twin, the A350, for single engined flight for as much seven hours from the nearest suitable emergency landing airstrip.

The story was kicked off by a detailed account of the Airbus ambition, and the regulatory context, in the Wall Street Journal.

But why? Although Airbus is clearly the source for the story, it is reluctant to be drawn on its reasons, or even to mention seven hours single engine speed within quotation marks.

Almost all medium to long range twin engined flights today operate to very stringent conditions which permit them to follow a route which at the furthest, is never more than 180 minutes single engined air speed under forecast conditions from an alternative or emergency landing strip which at the time of dispatch of the flight is open, and unencumbered by any advisory that it might not be open for the period of time that the flight in question will be in a position to have used it, if it had to.

On a case by case basis the US has allowed its flag carriers to fly modern twin-engined airliners up to 207 minutes single engine speed from some alternative airports in the North Pacific, which are far and few between, on US-Northern Asia routes. However contemporary Airbus and Boeing twin engined jets are designed for authority to fly at up to 330 minutes single engined airspeed for allowed alternative airstrips, but this is very rare in commercial scheduled airliner service using twin-engined wide bodies.

Notwithstanding the incredibly high reliability of current aero-engines and airframes the flight planning required for 180 minutes single airspeed rule routes is remarkably complex, linking up en route conditions, and the availability and extent of the these interlocked  ‘islands’ of permitted airspace to connect two remote points on the globe.

The result is sometimes not an optimal most direct or ‘great circle’ routing, and while it might mean a 14 hour flight takes an extra 45 minutes, over a years operations, that is a formidable bill for additional fuel, an impost on maintenance schedules, rostered hours and so forth. The same maintenance crew is not allowed to service both engines on a twin engined jet before its next flight, because of the risk that an oversight on one engine and its support systems might also occur on the other engine. In a worst case scenario this could lead to a dual engine failure, and a really bad hair day.

There is a degree of frustration in some places with the over regulation of twin engined flight, as perceived in some carriers, which is considered out of keeping with the exceptional reliability of the properly maintained twin engined airliner.  There is also a countervailing very strong reluctance on the part of the major national air safety regulators to relax the rules or their enforcement in any way, especially it seems, around Antarctica.

There are no jet airliner capable emergency landing strips on Antarctica. There are places that jet airliners land in Antarctica, such as McMurdo, Troll, Union Glacier and the Australian Antarctic Division’s Wilkins Blue Ice Runway, but  they do not even begin to come close to the requirements of a full on emergency landing facility for a scheduled airliner flight. And they won’t for a very long time, if ever.

So what was Airbus on about? The only places where an airliner’s certified capacity to fly at single engined speed for up to seven hours to an emergency landing strip would matter are found are along the possible near or trans Antarctica routes. Such as Sydney to Rio, or Perth to Sao Paulo, or Auckland to Johannesburg, or similar.

The commercial imperative to offer such routes may well arise, but perhaps not for 20 or 30 years, which may be beyond the relevance of today’s airliner designs to the environmental demands of the mid 21st century. Neither the problems that the world faces, nor the capacity of air transport technology, will remain static until the 2040s.

Nor is it realistic to envisage an FAA, nor a CASA, that would contemplate allowing for a scenario where a jet airliner with three or four hundred people on board, would be flying on a single engine over far southern latitudes.

What Airbus appears to be on about, is lifting the bar for on board systems and engine reliability and fire retardant capabilities for both under floor and in cabin crises to newer heights, because of its confidence in the all new A350 design. As such this is a very good thing. It will mean that all other contemporaneous Airbuses and Boeings will have to attain the same capabilities.

Eventually, if air transport goes down the path being pursued by Virgin Galactic, single engined cruise phase flight will apply to ultra fast journeys at extreme altitudes, and over equatorial to polar latitudes alike.  This early 21st century fixation with single engine reliability will belong to a quaint past, when our ancestors took almost a day to fly around the world, and the only A350s, or 777s, or anything of their ilk, will be in museums.

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