We had barely finished writing about the Tuesday aborted flight of a UA 787 due to an apparent oil filter problem, than breaking news arrives about another oil related problem, on another United 787, resulting in another emergency diversion and aborted flight.
United flight 125 was traveling from London to Houston today when, apparently over north Canada, a warning suggested the plane was low on oil. A decision was made to divert and land in New York, which the plane did, some 45 minutes later, and – more to the point – happily never being more than about 15 minutes from an even closer airport if the apparently low oil problem became a ‘no oil’ problem.
At this point United has not revealed if either problem was real or if they were both the result of faulty sensors. And it is also not clear if there is anything in common between the two faults other than the descriptions of each including the word ‘oil’ – oh yes, and the resulting outcome being an emergency diversion. United very quickly said the two incidents were unrelated.
But is it reassuring, as United doubtless hopes, if the two incidents are unrelated? Or does that alarm you even more to learn there may be two wildcard surprises lurking in the 787’s oil feed systems? I’d prefer it to be only one!
Here’s a Reuter’s report on Thursday’s problem. The one thing I disagree with is the claim ‘diversions of planes due to technical problems are not uncommon’.
Of course, they don’t quantify that claim, but it seems to me that diverting a plane due to technical problems is rare, and particularly rare for a plane with an extended ETOPS rating. You’re probably a frequent flier yourself, and you’ve probably had plenty of occasions when planes have been delayed on the ground for maintenance reasons, but when have you been on an international flight that had to divert and make an emergency landing due to a mechanical problem after it has started its flight? Maybe you’ve been diverted for weather issues, or perhaps even due to unruly passengers. But due to an in-flight problem with the plane itself? It has never happened to me, and I bet it has never happened to you, either.
So we view United’s two problems causing flights to be aborted, and related to two of its tiny fleet of six 787s, – in other words, one-third of its 787 fleet have had to abort flights within three days – as extremely unusual rather than ‘not uncommon’.
This second event underscores our concerns about the 787’s 180 minute ETOPs rating. The plane was ‘fast tracked’ by the FAA and Boeing and allowed to enjoy this extended duration rating (it means the plane can fly routes that takes it up to 180 minutes away from the nearest emergency diversion airport) without needing to prove itself by an extended period of safe flight. Previously, the FAA has insisted on planes operationally demonstrating their reliability and safety over a two-year period, but for the 787, it was happy to accept computer modeling and a very limited number of test flights.
Boeing’s assurances that the plane was suitable for immediate ETOPS approval were of course embarrassingly contradicted by the two battery fires which resulted in an almost exactly 100 day suspension of the plane’s operating authority, but when the plane was allowed to fly again, surprisingly its 180 minute ETOPS rating remained unchanged.
We’ve now seen two more events – unrelated to the batteries – that have required flights to divert and land. Happily, in both cases, airports were close at hand and the planes were not at the far away 180-minute-from-any-airport parts of their routes.
But, with the 180 minute certification still in place, how long before a plane does find itself in difficulties, and two or more hours from an airport?
The FAA has been extremely accommodating of the 787. Let’s hope that doesn’t prove to be a mistake.