Crash-landing at Heathrow : Just the Facts, Please

19 Jan 08 2 Comments

There is a lot of speculation going on in the press and, worse, a lot of speculation being presented as fact. The words “Absolute nonsense!” have become a frequent sound in our household as we read the articles in the popular press. I know accident reports aren’t everyone’s thing, but in the interests of understanding what happened, here is a quick run-down , based on the initial report.

Following an uneventful flight from Beijing, China, the aircraft was established on an ILS approach to Runway 27L at London Heathrow.

Nothing out of the ordinary until the final approach: that is the plane has already done its initial descent. The stewerdesses are buckled up and the plane is coming in to land. This is the hectic bit of the flight. A pilot friend of ours jokes that he gets paid for hours of boredom with a little bit of excitement at the beginning and the end. Some of the newspaper reports seem to almost imply that planes land themselves as they bandy about terms like Instrument Landing System and auto-thrust. Planes can land themselves in certain circumstances but it’s rough, we still prefer real people to put the planes onto the ground. It really is a safe assumption that the pilots would be giving the situation their full attention.

Initially the approach progressed normally, with the Autopilot and Autothrottle engaged, until the aircraft was at a height of approximately 600 ft and 2 miles from touch down.

At 600 feet they would be forty seconds away from anticipated touchdown. Then, something went wrong.

At approximately 600 ft and 2 miles from touch down, the Autothrottle demanded an increase in thrust from the two engines but the engines did not respond.

This is the loss of power: equivalent to putting your foot down and your car not accelerating.

Following further demands for increased thrust from the Autothrottle, and subsequently the flight crew moving the throttle levers, the engines similarly failed to respond.

The pilots immediately realised there was a problem and manually pushed the levers and got the same effect: no power.

Forty seconds is not a lot of time to make decisions and the ones we are hearing about in the press seem to have been sensible. Put the auxiliary power on. Don’t mess about with changing control, let the co-pilot land. Keep the plane in the air for as long as possible. Get the damn plane clear of the road.

The aircraft stopped on the very beginning of the paved surface of Runway 27L.

It seems likely that, given the time they had to make a decision, the pilots simply focused on getting that plane to the runway. They didn’t but they made it to the ground and cleared the perimeter fence: well done! There’s not a lot of options when you are in a 777 with no power, 600 feet above the ground.

The big question is: Why did the power fail? Any comment on that is complete speculation at the moment: the only information so far is why it didn’t.

A significant amount of fuel leaked from the aircraft but there was no fire.

We know for a fact that they were not out of fuel. We can probably rule out electrical fire based on the amount of fuel leaking without igniting. Interestingly, if the undercarriage had collapsed on the tarmac, there would have been a lot more sparks and very likely there would have been a fire, not that it’s likely that they aimed for the soft ground. One theory is that there was water in the fuel lines, which fits with the data we have so far. But honestly, until the plane has been examined, we just don’t know.

Initial indications from the interviews and Flight Recorder analyses show the flight and approach to have progressed normally until the aircraft was established on late finals for Runway 27L.

So interviews and the flight recorder are not showing an earlier fault in the plane. Now something went wrong, clearly. But this is why I don’t understand the press references to an alarm that apparently didn’t go off. They were 600 feet over the ground when they lost power – what good would an alarm have done?

We don’t know what caused the loss of power and the pilots didn’t have time to find out.

It seems to me that pilots did exactly the right thing: they flew the plane. It looks like they pulled the nose right up and kept that plane in the air for as long as they could. This would explain why one of the eyewitnesses describes a left bank when the plane would have been going straight in towards the runway: the wing dropped as a result of the slow speed of the plane as they tried to get it to the runway.

Having lost power, they can’t gain height, they can’t gain speed. The glide-path that they were on for the runway required more thrust which they didn’t have. The fact that they cleared the perimeter fence and made it to clear ground strikes me as nothing less than amazing.

I stopped reading the press reports when I saw one paper quoting an unnamed pilot explaining (badly) how the accident happened. I feel like asking the journalist where he gets his references. There are plenty of pilots out there posting sensible theories as to what went wrong but they aren’t keeping their identity hidden.

The next report will be made public in 30 days and I’ll make sure to post a link to it then.


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