AirAsia Flight QZ8501 Missing

[dutchroll]

http://www.smh.com.au/world/airasia-flight--qz8501-blackbox-from-plane-retrieved-20150112-12mdpo.html

 

The flight data recorder has been recovered, and the CVR has been located but not yet retrieved. Looks like people might have their answers soon enough.

 

 

[Old Koreelah]

All right you blokes; thanks for the interest. I'll put together a short piece, sanitising my contribution...

See new thread

http://www.recreationalflying.com/threads/jodel-d918.129994/

 

 

[Rotorwork]

Update from ABC

 

http://www.abc.net.au/news/2015-01-21/airasia-plane-climbed-at-speed-then-stalled-official-says/6029756

 

An AirAsia plane that crashed into the Java Sea last month with 162 people on board had climbed at a speed that was higher than normal and then stalled, Indonesia's transport minister says.

 

Flight QZ8501 went down on December 28 in stormy weather, during what was supposed to be a short trip from the Indonesian city of Surabaya to Singapore.

 

Indonesia's meteorological agency has said bad weather may have caused the crash, and investigators are analysing the data from the jet's black boxes before releasing a preliminary report.

 

Just moments before the plane disappeared off the radar, the pilot had asked to climb to avoid the storm. He was not immediately granted permission due to heavy air traffic.

 

"In the final minutes, the plane climbed at a speed which was beyond normal," transport minister Ignasius Jonan told reporters, citing radar data.

 

"The plane suddenly went up at a speed above the normal limit that it was able to climb to. Then it stalled."

 

Earlier at a parliamentary hearing, he said radar data showed the Airbus A320-200 appeared at one point to be climbing at a rate of 6,000 feet (1,800 metres) a minute before the crash.

 

There were several other planes in the area at the time.

 

"I think it is rare even for a fighter jet to be able to climb 6,000 feet per minute," Mr Jonan said.

 

"For a commercial flight, climbing around 1,000 to 2,000 (feet) is maybe already considered extraordinary, because it is not meant to climb that fast."

 

Human error or plane damage likely cause: investigators

 

His comments came after Indonesian investigators said they were focusing on the possibility of human error or problems with the plane having caused the crash, following an initial analysis of the cockpit voice recorder.

 

"We didn't hear any other person, no explosion," investigator Nurcahyo Utomo told reporters, explaining why terrorism had been ruled out.

 

Investigators from the National Transportation Safety Committee were now looking at the "possibility of plane damage and human factors", he said, without giving further details.

 

As well as the cockpit voice recorder, the committee is also examining a wealth of information in the flight data recorder, which monitors every major part of the plane. A preliminary report will be released on January 28.

 

There was a huge international hunt for the crashed plane, involving ships from several countries including the US and China.

 

Indonesian search and rescue teams have so far recovered just 53 bodies from the sea.

 

But last week a Singapore navy ship located the jet's main body, with the AirAsia motto "Now Everyone Can Fly" painted on the side. Rescue teams hope they will be able to find many more of the passengers and crew inside.

 

Divers have so far not succeeded in reaching the fuselage despite several attempts due to bad weather, high waves and strong underwater currents.

 

 

[dutchroll]

Comments on Tuesday from the Indonesian Transport Minister to their Parliament:

 

"I think it is rare even for a fighter jet to be able to climb 6000 feet (1800 metres) per minute," he said.

 

Utter bollocks. Any fighter jet can easily climb at rates far greater than 6000 ft/min. Even the B767 would do 6000 ft/min after takeoff at normal domestic flight takeoff weights until it got well into the 20's.

 

"For a commercial flight, climbing around 1000 to 2000 (feet, 305 to 610 metres) is maybe already considered extraordinary, because it is not meant to climb that fast."

 

Absolute nonsense. At medium weights or less, 1000 ft/min would be what you would expect, even at cruise altitudes in the mid 30's. Even at maximum takeoff weight, it will exceed this climb rate until getting close to its cruise altitude when the ROC will drop below that (for an Airbus - a Boeing will comfortably exceed 1000 ft/min climb pretty much all the way).

 

This is why politicians should not comment on aviation accidents.

 

The investigators will already have played the CVR recording and plugged the flight data into their computer simulators. They will already have a pretty good idea of what happened, but of course they need to be very careful before making public statements. I'd suggest the investigation sounds like it will discover pretty much what we thought it would (I personally think it will be a repeat of the AF447 accident, or at least with a number of similarities).

 

 

[planedriver]

Insufficient heating of pitot tubes in extreme icing conditions causing incorrect IAS, leading to stall?

 

You'd know a lot more than most of us about he possibility.

 

We'll probably have to wait for the final report.

 

 

[facthunter]

The high Rate of Climb could easily be because of an updraft. You just add the amount to the normal aircraft climb rate. I expect some extreme turbulence to be involved and possible structural failure. You just don't fly through that stuff. Nev

 

 

[dutchroll]

I'm betting there won't be a major structural failure, but I reckon stalling and failing to recover is highly likely. Icing probably involved too. The Airbus aircraft can have big problems if air data sensors (pitot, static, or AoA) get iced up.

 

 

[facthunter]

That's a lot of generalising about Airbus. AF 447 I would see as something that shouldn't have happened but for some unique circumstances. It landed in one piece with nothing to stop it flying, except the situation the pilots placed it in..

 

We will find out soon enough with the DATA available.this time much sooner. Nev

 

 

[Teckair]

The Airbus aircraft can have big problems if air data sensors (pitot, static, or AoA) get iced up.

Don't they have way of dealing with that? heated pitot and so on?

 

 

[facthunter]

They have more than one and are pretty exotic. Nev

 

 

[Teckair]

This is not my area of expertise, but some of the accidents I have seen on Air Crash Investigations on TV look avoidable like the one where the pilot let his kid fly the plane. When the co-pilot pulled it out of the spiral dive he just keeps hauling back on the stick until it stalls, it seems like some times with out the auto pilot they cannot cope. Actually I think the co-pilot may have stalled it twice wouldn't you think a look at the AH might be the way to go?.

 

 

[Yenn]

The pilots are supposed to have requested higher due to weather, but to have been denied due to other traffic.

 

If they couldn't climb because of other traffic, I would assume that traffic was above them and on their track, so they were either above the weather or it wasn't too bad.

 

If the weather that QZ5801 was in was bad enough to damage the plane the pilots should have declared an emergency, and either diverted or climbed advising ATC.

 

My personal opinion of Asian pilots is that they can fly the aeroplane OK until something goes wrong, then they get lost and I think that is what will be decided in this case.

 

 

[facthunter]

I don't really agree with much of that. These days Asians are trained as well as many others. Perhaps we should just wait and see. (It won't be long). I don't like using stereotypes. Nev

 

 

[rankamateur]

Nev, stick with your mono-types...

 

 

[Kyle Communications]

I have done a couple of million air km's working across the world back in the 90's and up to about 2006 and a lot of work was in or via or through Asian ports and I do have to say when I boarded the aircraft and I had a look up the front if there wasn't at least one round eye in the pit then I usually didn't get any sleep on those flights.

 

Mark

 

 

[dutchroll]

Don't they have way of dealing with that? heated pitot and so on?

Yeah they do, but the systems have been found wanting under extreme conditions. I don't know why. Boeing seem to manage just fine.

One issue is that the automatic flight envelope protection software uses the data from these systems. So for example, the low speed/stall protection system is wonderful when everything is working ok. Airbus procedure for a GPWS "pull up" warning is to pull full backstick and hold it there until clear of terrain, whereupon the aircraft will climb with the flight control system holding absolute max angle of attack (alpha-max) and sitting right on top of the low speed buffet until you command a pitch down. However if the AoA vanes are frozen, it can think you are approaching the stall and automatically lowers the nose to maintain what it thinks is alpha-max. It'll do this and you can pull back on the stick as hard as you like, with no effect! To get out of it, you have to force the plane into "Alternate Law", and the only way to do this is to turn off 2 out of your 3 air data computers. Then it'll revert to Alternate Law, it loses the flight envelope protection systems, and hey presto you can pull back on the stick and recover from the dive it has put you in! This has happened at least twice that I know of.

 

The flip side of this (and what happened to AF 447) is reversion to Alternate Law with no-one noticing, and losing the stall protection while thinking you still have it. They had conflicting airspeed indications due to icing, and the aircraft reverted to Alternate Law as it can do. Then they stalled it but the guy flying thought it was in Normal Law and held in full backstick - all the way to hitting the water - wondering why it wasn't climbing.

 

I think if this accident turns out to have some of these elements, Airbus are going to be in strife. They have outsmarted themselves with their flight control systems and have confused pilots (especially when faced with other conflicting flight path info) in the process.

 

 

[PA.]

This is why all Airbus planes should be equipped with fluffy dice hanging from the rear view mirror.

 

 

[facthunter]

Hope we aren't doing a Jabiru on Airbus. Boeing is a fine show, but they had a problem for a long while with the rudder actuating mechanism losing aircraft on 737's. I'm not too fussed with their "Dreamliner". Nev

 

 

[av8vfr]

I thought in an Airbus that the two sticks are not directly connected (fly by wire).. ie one can push full nose down and the other full nose up.

 

Is there a switch to transfer authority? Or is the captains stick in command at all times, with inputs from the FO only if the captain has no input?

 

 

[dutchroll]

I thought in an Airbus that the two sticks are not directly connected (fly by wire).. ie one can push full nose down and the other full nose up.Is there a switch to transfer authority? Or is the captains stick in command at all times, with inputs from the FO only if the captain has no input?

That is correct - they are pure fly-by-wire and are not connected to each other. This creates an interesting training and monitoring conundrum, as you can't really see what the other guy is actually doing with his sidestick.

The sidestick inputs in an Airbus are algebraically added by the flight control computer. So, Captain pulls full back, F/O pushes full forward, plane does nothing. The plane squawks a "DUAL INPUT" voice alert at you.

 

There's a red thumb button on each sidestick which functions as the autopilot disconnect. However it also functions as a sidestick takeover button. If you press it and hold it, for as long as you hold it, your sidestick takes over priority from the other guy. A red arrow illuminates on the glareshield in front of the guy losing authority, a green light illuminates in front of the guy gaining authority, and the plane squawks a "PRIORITY LEFT/RIGHT" voice alert.

 

Push and hold the same button for 40 seconds and the other guy's sidestick is locked out. A momentary press on either button will unlock it and revert the system to normal (this design aspect is for the case of an unconscious pilot who flops over on the stick).

 

 

[av8vfr]

So if both want priority, how does the aircraft react? Also, if the captain gains authority, a simple push on the FO button will diminish command?

 

Thanks for your insight Dutch, it's the digital flight system I am interested in... each aircraft manufacturer has its own flavour.

 

 

[dutchroll]

Whichever pilot last pressed the button and keeps it pressed will have exclusive command. If a pilot releases the button (except where they've kept it pressed for >40 sec), they essentially release the command authority of that sidestick and the system reverts to normal operation.

 

 

[dutchroll]

That's a lot of generalising about Airbus. AF 447 I would see as something that shouldn't have happened but for some unique circumstances. It landed in one piece with nothing to stop it flying, except the situation the pilots placed it in..We will find out soon enough with the DATA available.this time much sooner. Nev

Well, it's probably not unreasonable for me to generalise about the Airbus from my position. We discussed AF447 quite extensively during training with instructors who had many thousands of hours Airbus time.

Also I agree that Asian pilot training has come a long way, however the Asian culture of avoiding criticism or contradiction of authority figures has very deep roots way beyond just airline pilots and leads to steep cockpit gradients. This has been a factor in previous Asian airline accidents. Whether it's relevant to this one, I don't know.

 

 

[facthunter]

I don't think it is productive to assume things haven't improved. (and they certainly had to) and make a prejudgement on such a basis. The data will be available but it may not be publicly for a year. THAT is not satisfactory at all. Honeywell make the Flight management systems for both Manufacturers but the design philosophies are at some variance. I think basically both outfits make fairly acceptable aircraft that operate economically and reliably.

 

The PIC is "Master of the Vessel" and is ultimately responsible for it's safe operation. Challenging some authority when required is part of that function, and some aspects of Asian culture means there is sometimes reluctance to challenge. On that we agree. Nev

 

 

[bexrbetter]

This has been a factor in previous Asian airline accidents.

You know how big "Asia" is and how many countries and cultures it involves don't you?

 

and leads to steep cockpit gradients.

The worst airline disaster ever was directly due to this (Tenerife) and somewhat in 447 being compared here, besides many others not Asian in the slightest.