British Airways’ no power crash landing at London overnight shows what a difference a few minutes might have made for the worse for QF2 when it lost power approaching Bangkok on 7 January.

But apart from timing it means nothing. It was a different airline, flying a different type of Boeing which a few seconds sooner would have hit buildings or a busy road.

Dead lucky really. It could have hit birds, as some early reports insist. But there are reports that the captain said the avionics and engines failed simultaneously without warning.

No-one understands the BA crash at this moment. But the insights over the claimed dismantling of the Qantas safety culture in the pursuit of cost reduction bonuses continue to pile up following its own power failure incident.

Crikey has received this letter from a reader with a long professional involvement with flight standards in Australia.

The letter explains why the claimed backup battery supply of 60 minutes of power might in real life have barely covered the 15 minutes it took for QF2 to complete its descent to safety at Bangkok.

It describes how jets are being signed out fit to fly with absurdly long minimum equipment lists — or MELs — such as faulty galley drains or appliances, by people who are ill-equipped to understand or are dismissive of the safety-of-flight consequences because the bonus driven managers who prevail over people with technical knowledge are oblivious to the risks of mixing leaking water with electricity.

We know that the Boeing that operated QF2 had a power failure caused by leaking water because management said so. We know that other Qantas jets are being flown with faulty plumbing because passengers keep reporting them.

And we know this isn’t a result of excellence in Qantas standards. It is the result of signing out jets as fit to fly when it seems they are not fit. Half a dozen Qantas jets had plumbing repairs immediately after the Bangkok incident as the result of fleet wide spot checks within 24 hours.

QF2 points to a systemic failure in safety culture in the release of leaking jets into service, just as the Jetstar bungle at Tullamarine in fog last July points to deficient training for pilots in missed approach situations caused by poor visibility.

Qantas has been incredibly lucky in a number of incidents involving its “full service” and Jetstar operations, but if nothing else is done the dice can only be rolled so often before the luck stops.