AirAsia QZ8501 Missing

[RYH64E]

As I said before, if accident investigators don't need the fuselage then it's just a case of body retrieval, and dead is dead in my book. I am surprised though, the water is very shallow in absolute terms (only 30m or so, it could be 300m or 3000m!) so I don't see what the problem is (relatively speaking of course, I'm not suggesting I could do it in an afternoon).

[Vipers]

hornetrider said:

Looks like they're giving up attempting to bring it up

http://www.dailymail.co.uk/news/article-2929237/Ai...

I am wondering if the military has the expertise, knoweldge and ability to recover something this size in the first place, why didn't they (or someone), contract a salvage company who has the experience and track record.

Be a lot of moaning from the families knowing their loved ones are being left down on the sea bed. Tragic as it was, no expense was spared in the recovery of the debris and bodies from the Piper Alpha disaster, and that was a lot deeper.

Poor show I think.

[Blaster72]

Seems recovery is not off the cards after all

http://www.thestar.com.my/News/Nation/2015/01/28/Q...

[carinaman]

I assume this is news:

http://www.theguardian.com/world/2015/jan/30/airas...

[AyBee]

carinaman said:

I assume this is news:

http://www.theguardian.com/world/2015/jan/30/airas...

That's not good. Can't see why they would turn it off though - surely they're aware of what it's there for? Akin to turning off the parking sensors because they're telling you you're about to hit something and then hitting it!

[jmorgan]

Wish papers would report the whole story and if this means tit bits and speculation are left then so be it, the report in full should be the bit to carry the details.

[davepoth]

AyBee said:

carinaman said:

I assume this is news:

http://www.theguardian.com/world/2015/jan/30/airas...

That's not good. Can't see why they would turn it off though - surely they're aware of what it's there for? Akin to turning off the parking sensors because they're telling you you're about to hit something and then hitting it!

This is all supposition - but thinking back to AF447 the pitot heads got iced up meaning that the plane couldn't tell how fast it was going. That puts the flight computers into "alternate law" which effectively removes the stall protection.

If the pilots recognised that the computer wasn't going to do anything apart from telling them it had no idea how to stop the plane from stalling, I can understand them turning it off.

[mjb1]

Sounds like almost identical scenario to AF447.

[davepoth]

mjb1 said:

Sounds like almost identical scenario to AF447.

If (and it's a big if) that's what happened then they showed a little more understanding of the situation than the crew of AF447. I don't think it's by any means the whole story though.

[carinaman]

'Pitot heads'?

So what's the fix to stop them getting iced up in the future?

Secondary Pitot heads mounted elsewhere?

Pitot Heads double check themselves against the secondary Pitot Heads mounted elsewhere?

Run a heating element through them like heated windscreen washer jets?

Make the Pitot heads from a material that's less susceptible to freezing?

[Blaster72]

carinaman said:

'Pitot heads'?

So what's the fix to stop them getting iced up in the future?

Secondary Pitot heads mounted elsewhere?

Pitot Heads double check themselves against the secondary Pitot Heads mounted elsewhere?

Run a heating element through them like heated windscreen washer jets?

Make the Pitot heads from a material that's less susceptible to freezing?

They are already heated, there are already 3 separate heads for redundancy.
Adding more to the 3 already there would likely mean they are affected similarly.

They have a lot of redundancy already and the crews are supposed to be trained to react to loss of airspeed data using defined pitch and power settings (something reinforced in training since AF447).

If this accident really was caused by a poor reaction to the pitot probes icing over temporarily then the airline will be getting very uncomfortable indeed.

[carinaman]

Thanks Blaster.

[mjb1]

davepoth said:

mjb1 said:

Sounds like almost identical scenario to AF447.

If (and it's a big if) that's what happened then they showed a little more understanding of the situation than the crew of AF447. I don't think it's by any means the whole story though.

It definitely is a big 'if' at the moment, I'm speculating. When the pitot tubes froze and the speed reading was lost in AF447, the computer systems started reporting a catalog of failures of systems one after another (since they all depended in some way on the air speed input). The AF447 pilots were totally confused and sidetracked by the plethora of errors, and they missed the basic instrument indications. In this case it seems they did get a similar mass of errors, and did sensible thing and shut down the computer reporting the errors, but perhaps was too late too avoid the stall by then.

Do these aircraft have a ground speed readout (from gps?)? Could that be any help if air speed measurement is lost?

For anyone that hasn't seen it, here's the BBC documentary about AF447 (it was made before the black boxes were found, but it seemed to be a very accurate predction of what happened): https://www.youtube.com/watch?v=ecX1wxWjpgs

[davepoth]

mjb1 said:

Do these aircraft have a ground speed readout (from gps?)? Could that be any help if air speed measurement is lost?

We know from the radar trace that they had around 350kts across the ground just before they went down. Depending on what the wind was doing that could conceivably have been an airspeed of 550kts or 150kts depending on whether they were facing into the wind or not - and 150kts is fall out of the sky slow at those altitudes.

Because they were flying around near thunderstorms the winds are strong, gusty, and unpredictable, so without an indication of airspeed (or altitude for that matter since that works off a pitot tube too) they wouldn't have much of a clue what was happening because their instruments wouldn't have been working properly.

As per the above they're supposed to fly to pitch and power (i.e. a level pitch and 80% power (or something like that) will result in not stalling anywhere in the flight envelope) but if the weather conditions did get ridiculously extreme it's possible that they got outside of the flight envelope and didn't even realise before it was too late.

[BlackLabel]

article said:

A mid-air miscommunication between pilot and co-pilot in response to a recurring technical issue caused AirAsia flight QZ8501 to plunge into the Java Sea last December, Indonesian investigators have said.

The Airbus A320-200 was en route to Singapore from the Indonesian city of Surabaya on the morning of 28 December when it lost contact with air traffic control 42 minutes after takeoff

http://www.theguardian.com/world/2015/dec/01/airasia-crew-actions-caused-jet-to-lose-control-say-crash-investigators

[maxxy5]

It sounds scarily reminiscent of the Air France crash, pilots working against each other without realising.

[hidetheelephants]

maxxy5 said:

It sounds scarily reminiscent of the Air France crash, pilots working against each other without realising.

It does rather, another instance of pilots either distracted from the core activity of flying or simply not comprehending what the instruments and FBW are telling them. All the modern aids are making flight safer but without proper training and procedure they introduce new hazards in the place of those engineered out.

[essayer]

So at the end of it, stick back, aircraft stalled, wing dropped?
Appreciate it was in alternate law, but isn't that Flying 101?