News Air Asia flight QZ8501 missing

[Thunder Chicken]

About 24-30 meters in tropical waters - that's very shallow.

I read that there is a lot of sediment (relatively speaking) suspended in the water. They said if this were the dry season they would probably be able to see the wreckage from the air, even under 100 ft of water.

 

[Urwumpe]

I read that there is a lot of sediment (relatively speaking) suspended in the water. They said if this were the dry season they would probably be able to see the wreckage from the air, even under 100 ft of water.

Yeah, you also see that because of the greenish color, which suggest that the algae are pretty striving again there.

For comparison:

 

[garyw]

More news:

The cause of the crash is unknown but the plane encountered bad weather and asked for a flight path change before communication was lost.

'Broken condition'
The BBC's Alice Budisatrijo, who is on board an Indonesian warship with Gen Moeldoko, says a crane has been deployed to pull the tail out of the water. An attempt yesterday was hampered by strong currents and low visibility.

The rear part of the plane was spotted on Wednesday by an unmanned underwater vehicle at a depth of about 30 metres .

Authorities said it was upside down and partially buried about 30 km (20 miles) from the point of last contact with the plane, off the coast of Borneo.

Gen Moeldoko said on Friday the tail appeared to be in broken condition.

Authorities have been pulling bodies and wreckage from the sea but progress has been slow due to high waves and stormy weather.

Forty-six bodies have been retrieved so far. Search teams believe most of the remains may still be inside the fuselage of the plane which has yet to be found.

Source:http://www.bbc.com/news/world-asia-30738613
Emphasis mine.

That broken tail comment makes me wonder if this is another hard rudder movement that caused the tail fin to break off -> [ame="http://en.wikipedia.org/wiki/American_Airlines_Flight_587"]American Airlines Flight 587 - Wikipedia, the free encyclopedia[/ame]

 

[Urwumpe]

That broken tail comment makes me wonder if this is another hard rudder movement that caused the tail fin to break off -> American Airlines Flight 587 - Wikipedia, the free encyclopedia

Not unlikely. There are many more example where bad weather directly caused the rudder and the aircraft to part company.

---------- Post added 01-10-15 at 11:40 AM ---------- Previous post was 01-09-15 at 02:20 PM ----------

A part of the tail of the plane has been salvaged and will now be further investigated on land.

 

[Spacethingy]

Data recorder found and recovered, voice recorder possibly spotted by divers too:
http://www.bbc.co.uk/news/world-asia-30773782

How on earth is that thing still flying?!

 

[Urwumpe]

How on earth is that thing still flying?!

It was a testbed for investigating structural failures (but not that much of a testbed, that losing parts was planned), so this flight also had many Boeing engineers on the ground who assisted in getting it back despite the loss of the rudder in severe turbulence.

 

[ADSWNJ]

Flight data recorder now recovered and on land. They know where the cockpit voice recorder is too, but they need to clear more heavy debris to get to it. Well - it was a long time coming, but hopefully we will get initial data later this week.

Source: http://www.channelnewsasia.com/news/live-blog-retrieving-the/1583898.html

 

[Spacethingy]

The voice recorder has now been recovered too. Hopefully we'll soon know what happened...
http://www.bbc.co.uk/news/world-asia-30791524

 

[RisingFury]

How on earth is that thing still flying?!

The vertical fin doesn't provide lift, it provides stability. It ensures that the tail stays in the back and the plane doesn't rotate, but it's not the only surface that does that.

The fuselage itself plays a role as well, so does the drag of the tail.

Note that the center of gravity is somewhere beneath the main wing, so most of the fuselage is aft of it and the fuselage and tail gain a long lever.


When a plane loses the tail fin, there are three main differences:
- You lose control of yaw and have to use roll to control it.
- Plane becomes nose heavy because it lost weight far at the back. Some trim up is needed.
- Plane slides into the turn when you bank.

It obviously doesn't become impossible to fly the plane. It just makes it more difficult.

In recent years, there's been quite a bit of research on aircraft with no vertical tail fin. If stability can be ensured through other means, one can get rid of the aerodynamic parasite that is the fin

 

[boogabooga]

In recent years, there's been quite a bit of research on aircraft with no vertical tail fin. If stability can be ensured through other means, one can get rid of the aerodynamic parasite that is the fin

If the rudder was necessary, birds would have them:

https://www.youtube.com/watch?v=Hr0I6wBFGpY

 

[Artlav]

If the rudder was necessary, birds would have them:

Birds can also flip their tail 90 degrees or more along the axis, and in general have a wider range of airfoil motions.

I think the difference can be expressed as in between a cartesian plotter drawing on a piece of paper, and a human hand doing the drawing.
The latter is more compact, the former is much easier to control.

 

[RisingFury]

If the rudder was necessary, birds would have them:

https://www.youtube.com/watch?v=Hr0I6wBFGpY

They DO have them!!! Sort of...

The tail works as a rudder. They don't just deflect the tail up and down, but they also turn it, so that part of the tail is vertical and acts as a rudder.

What do we have in terms of technological equivalence? V-tail!

I chose this terror drone because birds also shape their tail downwards a bit in turns. Just not by that much.

 

[Urwumpe]

Some more information from the first analysis of the CVR:

No terror attack or other intrusion or threat to the cockpit crew.
Crew is heard being really busy to keep the aircraft on course.
Everything on the tape was equally well audible (no sign of decompression for example)
Last minutes of audio are full of engine sounds and warnings (beside the crew communication)

More details will come with the regular investigation, that's just the first information that can be confirmed with certainty.

 

[Buck Rogers]

How on earth is that thing still flying?!

I've landed several planes in that, and much worse conditions in IL2.
Once practicing stunts looping under low bridges, ripped the tail off an aircobra, landing proved especially difficult due to the mid-engine design! Avoid flat spins at all costs!

 

[kuddel]

Some more information from the first analysis of the CVR:

No terror attack or other intrusion or threat to the cockpit crew.
Crew is heard being really busy to keep the aircraft on course.
Everything on the tape was equally well audible (no sign of decompression for example)
Last minutes of audio are full of engine sounds and warnings (beside the crew communication)

More details will come with the regular investigation, that's just the first information that can be confirmed with certainty.

As you would reply: "source?!"

 

[Urwumpe]

As you would reply: "source?!"

For example:

http://www.usatoday.com/story/news/world/2015/01/19/no-evidence-terrorism-airasia/21988747/

---------- Post added at 07:37 PM ---------- Previous post was at 12:15 AM ----------

Ignasius Jonan, the minister of transportation in Indonesia, has reported that the aircraft climbed with 6000 ft/min for a short instance before stalling, according to ground radar observations.

http://www.bbc.com/news/world-asia-30902237

Thats a tiny bit extreme for an airliner - this means it climbed at about 7° FPA at cruise speed in 10 km altitude.

 

[Spacethingy]

So, did it simply hit a massive storm updraught that ripped it apart? (6000 fpm is roughly 70 mph).

 

[ex-orbinaut]

Hmm. From what I have been hearing so far it looks like they might have been caught out by a known FMGS software "gotcha" (bug) of the Airbus, which all A320 family crews should be aware of regarding Open Climb vertical mode. It is the zoom climb attempt.

Flying along at cruising speed, you decide to trade speed for altitude to get up there quickly, so you wind back the selected speed then select a higher altitude of the FCU and pull open climb. As selection of the speed took effect first, the engines are already throttling back, and they stay that way until the indicated speed drops to the selected speed, then start spooling up. In the meantime, the aircraft has assumed a pretty hefty nose up attitude and bleeds off the speed very quickly, with no power on.

The zoom climb can be done, but it is done the other way around; you select the higher altitude with open climb first, wait for the engines to spool up, then wind the speed down. The engines do not throttle down under this condition, if the climb is already established. That said, it is a procedure of great caution, really, and crews are warned about it. I personally think its employment should be avoided, and selected speed changes during open climb phases limited to only ten knots at a time to avoid violent speed hunting pitch ups.

If the aircraft was in an up draught at the time of the selection and transitioned into a down draught at a critical moment of low speed / low power / high pitch, I can imagine the effects would be catastrophic, overwhelming the low airspeed protection while it proceeded to attempt to overcome aircraft inertia combined with low airflow speed response to the controls, from a nose high attitude. Scary, if that was combined with an aft loaded CG (within limits of course), which is common practice in airlines because it saves fuel in cruise.

Of course, I am allowing a bit of speculation here, it could be something very different, or merely a contributing factor among others, but it looks mighty like it. And I am not making up the Open Climb bug, either. Here's a mention of it, and it should be among the factors considered in this case...

PPruNe

 

[Graham2001]

For some reason I am thinking of a China Airline crashe where someone hit the Take Off/Go Around switch by mistake.

[ame="http://en.wikipedia.org/wiki/China_Airlines_Flight_140"]Wikipedia: China Airlines Flight 140[/ame]


There have also been other incidents, some of them fatal when pilots make mistakes with the aircrafts pitch control and automation.

[ame="http://en.wikipedia.org/wiki/XL_Airways_Germany_Flight_888T"]Wikipedia: XL Airways Germany Flight 888T[/ame]

 

[steph]

There also was a rather less known (at the time) incident with a Tarom A310, which happened on approach. Apparently, they were coming too high and too fast and the pilots lowered the flaps at or around the limit speed for that flaps setting, which caused the aircraft to switch to "alternate law" or how it's called, revv-up the engines and set the trim for full nose-up.

Voice recordings aren't that full of info. Other than "WTF is it doing?" and "It's doing a go-around", most of it is expletives.

Coming to think of it, I've grown quite trustful of the A320, as I've flown on it 8 times so far. There was this one flight that had some "hiccups", tho. Plane came late due to having to undergo a maintenance landing on the inbound flight. When we boarded, the pilot and some guy from the ground crew kept looking into one of the engines with flashlights, and manually spinning the fan . During ascent, it made a series of sharp turns which felt like going around in a figure eight (sharp turn to the left, then to the right and repeat). Then we circled once or twice over what I later found out was Frankfurt. And occasionally there were some noticeable engine rpm variations, probably coming from the previously-inspected one. Flight arrived late, but with no other issues.