Airasia: ice brings down plane

[dave_091]

I simply don't agree with this as being the sole problem. Why wouldn't they have communicated with ATC? There was no sign of distress. There is more to this.

http://www.theglobeandmail.com/news/wor ... e22288450/

[pdw]

Even if an engine thrust is only slightly reduced / not even noticeable on account of the fine "ice particles" (a reference from 'NASA research' in the article) it would be making a defining contribution into 'stall accident' in or near that convective activity (the radar image for that time/altitude and co-ordinates) ... at least it seems like that's what they are trying to say in there ...

[ahramin]

Think about what it would be like in the cockpit after a double engine failure or rollback. The Captain should immediately take control, stuff the nose down (not sure about the 320 but somewhere around .82/300) and try to get out of the conditions that caused the problem (usually a 180), then head for somewhere safe. The F/O goes heads down trying to get the engines back jumping from ECAM to paper QRH. There's a spot for the F/O to notify ATC but it could easily be missed or disregarded. A sharp F/O will use any spare time waiting for the engines to start up or spool down to help the Captain navigate the aircraft and troubleshoot the cause of the engine failure.

If all the above doesn't get done well under stressful circumstances, it's easy to turn it into an Air France. Even if they don't stall it, it's still possible to fail to get the engines restarted and end up in the water. It's perfectly possible for either of those to happen without a Notify ATC getting done or being done improperly and not being heard.

I haven't kept track of the media crap on this one, we'll find out eventually what actually happened. No idea if ice particles are what took out this plane but it's not a well known or understood phenomenon and bears discussion for it's own sake.

[Diadem]

The likelihood of both engines failing simultaneously is extremely remote, so I find it hard to believe that they didn't have a chance to make a mayday call if that was the case. With one engine running they would still be flying, and without knowing what caused the failure they probably wouldn't try to restart it right away. Not until the second one failed would they find themselves so task-saturated that they couldn't make a quick radio call.

[CpnCrunch]

Sounds like a bunch of speculation at this point. We're also hearing that the pilot apparently ploughed straight into the thunderstorm after being denied permission by ATC to climb, and that they didn't even have a permit to fly their scheduled route that day, and didn't have a permit to land where they were going to land. All in all it sounds like a half-assed airline (or regulator?), so nothing will surprise me about the cause of this accident.

[GyvAir]

I've been browsing through the news on this one most days. The speculation is pretty rampant and in many cases presented as fact or conclusive either by the speculators or the media. Even information that should be simple, such as counts of bodies recovered swings wildly up and down. In a way though, it seems like most of the officials involved may actually be doing a decent job of preventing leaking of incomplete information investigation wise, as it seems like the media dogs have had precious few bones of that sort to chew on in this one.

[Canoehead]

Air BC and Air Nova experienced some rollback issues back in the BA-146 days, caused by the perfect combination of atmospheric conditions and power settings. One of the Air BC guys flew with me on the DH8 in the past, and he told me the story of his encounter (I believe they were enroute from YWG to DEN). As I recall, 3 of the 4 engines rolled back within minutes of each other- Im unsure of the details except that they did a hell of a job to try and get stuff restored. They briefed the cabin crew on an "off-airport landing". At about 4-5000' they managed to get some of them back at a reduced thrust setting and were able to limp into the airport. It was amazing stuff. Staying in control of the airplane saved their bacon.


Edited because Google is smart

[ajet32]

Well they were approved by the Singapore regulator to operate 7 days a week Surabaya to Singapore so that part of the above comment is wrong. As for the lack of Indonesian approval, well maybe they were and maybe they weren't. This would appear to be typical cover your a__ maneuver by the DGCA. When in doubt suspend a few people to make it look like your doing something. Assure blame lies anywhere but on your own shoulders.
Air Asia is a well run airline that I have flown on several times while working in Indonesia. Good crews and for a LCC very good cabin service. I suspect this will turn out to be a bad decision made in the heat of the moment. One that was made many times and this time didn't work. If you don't fly when there are thunderstorms in rainy season then you can stop flying for 4 months. As for the lack of briefing by a FOO well all they do is read the weather to you so most pilots can read a TAF, Metar and PROG chart them selves and make decisions.
The regulator is less than ideal but then are any of them really good any more.
Let's wait for the investigators to find something of value instead of media speculation.

[pdw]

The Indonesian weather office released it, so likely also their scientists studying it, being in the area where most cases have been over the years.

I haven't kept track of the media crap on this one, we'll find out eventually what actually happened. No idea if ice particles are what took out this plane but it's not a well known or understood phenomenon and bears discussion for it's own sake.

From the article:

--" involves ice particles some as small as a grain of flour "

--" pilots have said their flight conditions were unremarkable, with only light turbulence and something that looked like rain, when engines suddenly shut down "

--" it grew clear that somehow dense clouds of particles were actually cooling the inside of the engine enough to cause freezing "
( " one incident the paper studied suggested very heavy snow could have the same effect " )

-- " a phenomenon that NASA has called 'a modern day mystery'. In the right conditions, the core of a jet engine that normally operates at 1600 deg Celsius can be so badly frozen it slows, or shuts down altogether "

Certainly the 'phase change of water-into-ice heatloss-numbers' apply here, which is that any amount of moisture cooling thru its freezing point to become "ice particles" first loses as much heat as it would take to heat an equivalent amount of H20 from zero C to about 60-70C ... and that's just to turn the moisture into ice at ZERO-C. After that, if cooled even colder to minus 10 20 30 40, any additional amount of heat from each ice particle is lost at the normal / sensible rate for each degree of temp-loss. Void of all that heat, and when flying into an area with the unusual denser concentration of these, it reads in there as if part of the problem is some severe 'lowering of the temperature' of "core" engine metal that these "particles" are flowing by ... even way down to the point of "freezing" the engine (the dysfunction) ... if I'm reading that correctly.

Wouldn't surprised me if high enough "particle" concentrations are occurring more often in those places where on a more continuous basis the warmer air masses of optimal moisture being forced up in a certain way (ie more rapidly and on a wider scale) that's necessary to produce them.

[GyvAir]

When aircraft engines are stopped due to this phenomenon, would the FDR and/or engine monitors record adequate information to accurately diagnose what happened, in a post-accident scenario, where the data recordings and possibly inspecting the engines themselves is all there is to go by?

[pdw]

OK that's asking about the parameters a flight recorder has input of to divulge any 'less than ideal engine-function ... which so far maybe was just not enough information on its own without the firm/underlying knowledge base supported by weather analysts that shows how the potential downpowering by the "ice particles" is possible ?

EDIT: for punctuation

[Heliian]

I'm putting my money on lightning strike followed by catastrophic explosion and breakup. Or aliens.

[ahramin]

The likelihood of both engines failing simultaneously is extremely remote

Actually, in the majority of the few cases recorded of inflight shutdowns caused by high altitude ice crystal, both engines are affected at the same time.