Eric Moody, pilot who saved plane from ash cloud, dies at 82

Tributes have been paid to the former British Airways captain, Eric Moody, who has died at the age of 82. Captain Moody saved hundreds of people from certain death after the plane’s Rolls-Royce engines were paralysed by a cloud of volcanic ash. Rory Clarkson is a senior engineer at Rolls-Royce, who makes sure that the engines function in challenging weather conditions...

Rory - The flight we are talking about was a British Airways flight from London to Melbourne. But in those days, in 1982, they didn't do it directly, they would do it in legs. So the leg they were on was between Kuala Lumpur and Perth. And from Perth that they'd fly out to Melbourne and they were totally unaware that they'd been a volcano that erupted. All they knew was that strange things started happening. The cabin started to fill with a smoky like dust that smelled a bit acrid. And then they started to see St. Elmo's fire, which is an electrostatic discharge on the windscreen, lights flickering in the night. And then they started to pick up that the engines were starting to misbehave, and within a few minutes, one engine stopped and then the other three stopped in sequence. And they were then essentially in a glide.

Chris - I think Captain Moody calculated they had about 20 minutes of glide time before they would end up in the ocean or something. Wasn't it?

Rory - It was of that order, yeah. So they were at 36,000 feet, so they had some time to react. Eric Moody issued a famous warning to the passengers, 'ladies and gentlemen, that I'm your captain and we've got a bit of a problem. All four engines have stopped. We are doing our damnedest to get them going again'. To their credit, and this is what saved the day, they didn't give up on the engines, they kept trying to restart them and eventually they could restart them.

Chris - What did Eric Moody do that meant they did get them started again? Is there a kind of protocol under these circumstances that you can resort to and did they do that, or did they end up resorting to other measures to try to get the plane flying properly again?

Rory - There was a protocol, the appropriate one, when you lose power on all engines to follow, which is what they did, which was to turn left and descend and try and find a suitable place to put the aircraft down as safely as you could. But as I said, the key thing was they kept trying to relight the engines. And because of the effect volcanic ash has on the engines, how it stops them, it meant that by the time they were getting down to about 16,000 feet, it was actually possible to restart the engines. And having restarted them, they gained enough power that half an hour later they could get and land at Jakarta.

Chris - Was it that at that altitude and with that change in direction, they just left the ash cloud, so they're actually feeding fresh air back into those engines again. So they had a better chance of getting them to restart?

Rory - No, it wasn't to do with that. We need to understand why the engine stop in the first place. And then you need to understand a bit about how a jet engine works. So it's a bit like a propeller aircraft, but a bit more complex in the middle. So the air comes in at the front and it has to be compressed to high pressure. It's about 30 to 40 times the pressure of the atmosphere, and then you put fuel in it, and then you double the temperature of the fuel, of the gas. And then you put that through what we call a turbine, which is like a windmill. And it extracts energy from that high pressure hot gas. And that's used to drive the compressors at the front. To keep that whole system going. Once you've ignited it, you don't need to keep reigniting it like you would in a car petrol engine. It's more like a gas hob on a gas cooker. But the amount of air that you are pushing through the engine is controlled by a key component just downstream of where you're putting the fuel in and burning it and it controls the total flow of air through the engine. And it's so hot that it would melt the volcanic ash and it would build up on those surfaces and it would start to restrict the flow through the engine. And if you lose about 10 to 20% of the flow through the engine, the whole engine stops working. And that's what happened. They were in the ash sufficiently long, about four minutes, that they built up enough ash on that critical flow area to stop it working. Now, they didn't completely block the flow area, they just reduced it by that amount so that at 36,000 feet, the engine wouldn't work. And by the time they got down to 16,000 feet, 13,000 feet kind of range, they could get enough air through the engine because the air's thicker at those altitudes compared to 36,000 feet. They could get the bunsen burner flame lit and stabilised and pull away to power. So that's what saved the day.

Chris - Those engines were Rolls Royce engines that were on that plane that day. So I don't know if you actually worked on them or one similar, but when something like this happens, do you get to then take them to pieces to work out what had happened and then use that as a learning opportunity?

Rory - Fortunately, the industry's not had an incident like that really since the 1990s. But what was great was in the 80's and 90's when these incidents happened, they did return the engines to the overhaul shops and they stripped them right down to the part level, component level. And they took a lot of photographs and they wrote up what they found in reports. So I had access to those reports. And although they, at the time, didn't fully understand the evidence that they were looking at, fortunately with the advances in science we've had since then, I was able to piece together what had happened in detail and relate that to modern engines, the engines that are powering aircraft today. We've demonstrated the level of volcanic exposure they can tolerate in which it's safe to fly.

Chris - And you also spoke to Eric Moody himself a couple of times. Was he the cool customer that he's conveyed as being? He joked when they got off that plane, when he landed it, the engineer kissed the ground and said, 'the Pope does this.' And Eric Moody said, 'that's 'cause he flies Air Alitalia' <laugh>. But <laugh> was he as cool on the phone to you when you spoke to him?

Rory - Yeah, he was, he was incredibly relaxed and philosophical about it. But he was great to talk to. I I had two long conversations with him because I wanted to get as much technical detail about what he remembered from the flight and immediately afterwards and it was really, really useful to my work. But yeah, he was charming. There was a sense of humour about what he said, and I think that's probably what helped on the day because he could keep calm. He kept everybody on the aircraft, his flight crew, he tried to keep them as calm as he could. And, yeah, he was a great guy to talk to.