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BetaDust
2009-Feb-25, 10:08 PM
(CNN) -- A Turkish passenger jet crashed as it tried to land at Amsterdam's main airport Wednesday,
killing at least nine people and injuring more than 55, Dutch airport authorities have said.


http://edition.cnn.com/2009/WORLD/europe/02/25/turkish.plane.amsterdam/index.html

A Very Sad Day :(

Moose
2009-Feb-25, 10:11 PM
Well, on the bright side, injuring "more than 55" means >55 survivors, which is better than the usual outcomes.

mahesh
2009-Feb-25, 11:05 PM
Sorry, BetaDust

edit:

...and the two pilots, plus an apprentice pilot, didn't make it :(

BetaDust
2009-Feb-25, 11:47 PM
It's up to nine fatalities now. :(

http://www.nu.nl/algemeen/1923104/negen-doden-bij-vliegtuigcrash-schiphol.html

I only have a Dutch link, sorry.

mahesh
2009-Feb-25, 11:56 PM
BetaDust...
allow me to add a few...is that okay?

at BBC, main one:
http://news.bbc.co.uk/1/hi/world/europe/7909683.stm

and you could pick more from the links...

mugaliens
2009-Feb-26, 08:47 PM
What's interesting is that just a week ago, the employees of that airline posted to the Internet some very scathing remarks highlighting that airline's apparent lack of regard to safety.

A friend from work pointed it out. I'll see if I can get him to send me the link, if it's still up.

slang
2009-Feb-26, 09:05 PM
The dead have been identified as 5 (at least 3 crew) Turkish people, and 4 Americans. 6 people are severely wounded (as in fighting for their life), AFAIK they have not been identified yet. Not formally, anyway.

ETA: no news yet about the cause, black boxes are being examined in a French institute that does have the proper reader for it, according to dutch media.

mahesh
2009-Feb-26, 09:27 PM
This is at 18.50 hrs from yesterday....
http://news.bbc.co.uk/1/hi/world/europe/7911228.stm

I haven't come across any updates (BBC). You might already know about the above.

slang
2009-Feb-26, 10:00 PM
This is at 18.50 hrs from yesterday....
http://news.bbc.co.uk/1/hi/world/europe/7911228.stm

I haven't come across any updates (BBC). You might already know about the above.

Yeah, it doesn't really say anything except some general info. Any comment about the cause would be speculation. And many are speculating already. Maybe one of them will be right.. or maybe the root cause will be surprising. They say the results from the black boxes will be in next monday.

mahesh
2009-Feb-26, 10:08 PM
yeah as the Dutch rescue workers were saying last night, anything said now, is going to be speculative.

I was surprised that the BBC reporter at the site, well in Holland anyway, posed his question in such a silly manner, like asking him, if he knew the cause of the crash!!!! should be sent back to journalism school. silly cow!

Analysis of the black boxes will take time and we have to wait for the investigating authorities to make their observations.

Jens
2009-Feb-27, 05:02 AM
In one article, I found an interesting comment from the Turkish transport ministry:

Paying tribute to the efforts of Captain Hasan Tahsin Arisan, the Turkish transport minister said: "At the cost of his own life, [he] ensured that human casualties were low."

It piqued my interest. Has there every been a case where an airline pilot left the controls to try to run to the back of the plane or something like that? I've never heard of it happening, and can't really imagine it happening. I would suspect that pilots are basically aware that (a) even if they are at the front, their individual chance of survival is still better than abandoning the controls, and (b) if the situation is so bad that they can run to the back of the plane, it won't make a difference anyway. It doesn't seem heroic.

BetaDust
2009-Feb-27, 04:09 PM
SEATTLE Boeing Co. says two of its employees were among nine people who died when a Turkish Airlines jetliner crashed into a muddy field in the Netherlands.

Yahoo (http://news.yahoo.com/s/ap/20090227/ap_on_re_us/netherlands_plane_crash_boeing)

slang
2009-Feb-27, 04:32 PM
Latest rumors (Dutch paper, quoting Turkish pilots association) say the 737-800 may have hit the wake of a 757 that allegedly landed 2 minutes earlier. According to a Dutch passenger the engines didn't stop working, and the pilot actually revved them up after they seemed to have hit an airpocket or downdraft or something like that.

Does anyone know how much time separation is required after a 757 lands, for an aircraft this size?

Larry Jacks
2009-Feb-27, 07:39 PM
Does anyone know how much time separation is required after a 757 lands, for an aircraft this size?

According to this chart (http://www.faa.gov/airports_airtraffic/air_traffic/nas_redesign/regional_guidance/eastern_reg/nynjphl_redesign/dei_statement/vol_2/media/fig_1_04_AircraftSeparation.pdf), the normal separation required for landing behind a 757 is 4 miles. Reportedly, the 757 produces more wake turbulence the most other airliners other than the heavies (e.g. 747). At normal approach speeds, a 2 minute separation should be about 4 miles.

slang
2009-Feb-27, 09:55 PM
the normal separation required for landing behind a 757 is 4 miles. [...] At normal approach speeds, a 2 minute separation should be about 4 miles.

Thanks Larry. So at first glance the pilots association remark seems to be a on shaky footing. I hate all that blame assigning before even the most basic facts are well established...

BetaDust
2009-Feb-28, 12:08 PM
Latest rumors (Dutch paper, quoting Turkish pilots association) say the 737-800 may have hit the wake of a 757 that allegedly landed 2 minutes earlier.

From Yahoo: (http://news.yahoo.com/s/ap/20090228/ap_on_re_eu/eu_turkey_netherlands_plane_crash_2)


Turkey Airline Pilots' Association Secretary-General Savas Sen said late Friday that a large Boeing 757 had landed at Schiphol Airport two minutes earlier. Sen said that plane most likely created "wake turbulence" that hampered the Turkish aircraft's landing.

mahesh
2009-Feb-28, 12:18 PM
Think there was a 'wake-turbulence' accident, unfortunately, on take-off too, a few years ago...similar larger / smaller plane combination...

mugaliens
2009-Mar-02, 07:23 PM
Larry Jacks - you're right on! Regarding wake turbulence, 2 minutes is typical. It's more of a factor on take-offs than landings, though. Wake turbulence travels downwards. Assuming airplanes are landing into the wind, even minimal separation on landing will provide wake turbulence clearance. On takeoff, however, the upwards angle means the down and back travel of the wake turbulence can stay in one spot!

Thus, the main criteria for safe sequencing for landing is ensuring the aircraft in front is able to get clear of the runway before the next aircraft touches down, while the main criteria for safe sequencing for taking off is wake turbulence. Wake turbulence is also aircraft category dependant, and it's not uncommon to use a 3 minute interval under the right conditions with a lighter aircraft taking off after a much heavier aircraft.


In one article, I found an interesting comment from the Turkish transport ministry:

Paying tribute to the efforts of Captain Hasan Tahsin Arisan, the Turkish transport minister said: "At the cost of his own life, [he] ensured that human casualties were low."

It piqued my interest. Has there every been a case where an airline pilot left the controls to try to run to the back of the plane or something like that? I've never heard of it happening, and can't really imagine it happening. I would suspect that pilots are basically aware that (a) even if they are at the front, their individual chance of survival is still better than abandoning the controls, and (b) if the situation is so bad that they can run to the back of the plane, it won't make a difference anyway. It doesn't seem heroic.

It has nothing to do with heroism. Whatever the pilots do to increase their chances of survival will increase the chances of survival of their passengers.

As for running to the back of the aircraft, what for? To go potty? There are no parachutes on airliners... :)

farmerjumperdon
2009-Mar-02, 07:43 PM
Thanks Larry. So at first glance the pilots association remark seems to be a on shaky footing. I hate all that blame assigning before even the most basic facts are well established...

You can also bet on the fact that the guideline errors considerably on the safe side. I've watched them landing at MSP and it seems they are damn near wheels down as soon as the plane taking off is wheels up.

Larry Jacks
2009-Mar-02, 08:36 PM
Just to show how many possible causes there could be for an accident like this, here's a short list of things that could cause a crash where the plane was lined up on the runway but landed well short.

1. Lack of vertical guidance (glide slope) and crew inattention causing a controlled flight into terrain (CFIT) like that 747 accident at Guam a number of years ago.

2. Engine loss of thrust causing the plane to land short like that 777 at Heathrow (last year, IIRC). That could be caused by things such as fuel starvation (running out of fuel or fuel blockage) or engine controller malfunction.

3. Loss of engine thrust due to mechanical failure - possible but unlikely for both engines to fail on approach.

No doubt, there are other possible causes. My point is that the accident investigators are pouring over the cockpit voice and flight data recorders as well as the wreckage looking for the cause (or causes). I'm not speculating as to the cause of this crash. I'm just trying to point out how many possible causes there could be for a crash of this nature.

slang
2009-Mar-02, 10:06 PM
No doubt, there are other possible causes.

Indeed, with undershoot being reasonably common.


My point is that the accident investigators are pouring over the cockpit voice and flight data recorders as well as the wreckage looking for the cause (or causes). I'm not speculating as to the cause of this crash. I'm just trying to point out how many possible causes there could be for a crash of this nature.

I wholeheartedly agree. I guess some media will write down any comment by anyone without any rigorous fact checking.

Nicolas
2009-Mar-03, 08:15 PM
Regarding an earlier comment: as he's in trouble as much as anyone else aboard, trying to make the crash as gentle as possible isn't heroic an sich. What is good, is that a (good) pilot stays calm enough to try to choose the best possible crash site for the people aboard and on the ground. That doesn't really apply here (I assume that there was little control left, though it appears the pilot managed to get the plane quite level just before the crash), however the plane is very close to the highway and a house; I can imagine he tried to miss them when chances for a decent landing were lost anyway. Of course, that is something that both the people on the ground and on board benefit from, as in general it's better to plow into a field than into a building with your plane if you want to survive it. So in a way, that still isn't truly heroic as the pilot himself also benefits from it. The heroic part is the ability to stay reasonably calm, save what can be saved and not run down to the back of the plane in panic.

I've actually seen the crash site this sunday (had to pass there, didn't go there on purpose). A quite short track behind the plane and a plane that is "blended" with the field quite a bit, in other words it smacked more or less straight down.

In a way, we've been lucky with the outcomes of plane crashes lately. A320 crashes into the Hudson: no casualties. Helicopter with 18 people on board crashes into the North Sea: no casualties. 737 crashes into a field and breaks in three parts: only 9 casualties. That could easily have been hundreds of casualties.

Larry Jacks
2009-Mar-03, 09:40 PM
Regarding an earlier comment: as he's in trouble as much as anyone else aboard, trying to make the crash as gentle as possible isn't heroic an sich.

It's said that the pilot is always the first on the scene of an accident.

I've actually seen the crash site this sunday (had to pass there, didn't go there on purpose). A quite short track behind the plane and a plane that is "blended" with the field quite a bit, in other words it smacked more or less straight down.

It sounds like either the plane stopped very quickly or hit with a high descent rate. Either can cause a lot of G forces on the passengers.

In a way, we've been lucky with the outcomes of plane crashes lately. A320 crashes into the Hudson: no casualties. Helicopter with 18 people on board crashes into the North Sea: no casualties. 737 crashes into a field and breaks in three parts: only 9 casualties. That could easily have been hundreds of casualties.

We also had that Dash 8 crash in Buffalo, NY killing about 49 people on board and 1 man on the ground. There was also a 737 that ran off the side of a runway (http://www.wjla.com/news/stories/1208/579754.html) in Denver last December. There were no fatalities but quite a few injuries. A lot of people are surprised to learn that most airline accidents are survivable.

One minor point - in the military, the definition of the word "casualty" isn't limited to those killed in action. A casualty is anyone who is killed, wounded, missing in action, or captured. In other words, anyone who is no longer able to serve their assigned duties. I think the same definition should apply for civilian accidents. "Casualty rate" and "fatality rate" aren't the same thing.

slang
2009-Mar-03, 10:55 PM
Regarding an earlier comment: as he's in trouble as much as anyone else aboard, trying to make the crash as gentle as possible isn't heroic an sich.

It's said that the pilot is always the first on the scene of an accident.

They were on this one... cockpit detached from fuselage. It's said they hit tail first, maybe that resulted in a forward tumble that made the cockpit impact so hard that it detached from fuselage and dug in much deeper... that seems to have been what killed the pilots, crushed by panels hitting them from behind (according to media). Poor guys, the only ones that knew exactly what was coming.. If it were me I'd just hope it was quick.

slang
2009-Mar-04, 03:16 PM
Preliminary findings show that at 1950 ft the left radio altimeter gave a faulty indication of ground level, which in turn caused the autopilot to reduce throttle to idle. Only below 500 ft altitude power to engines was restored, after the stick shaker went active.

I assume the re-application of power was too late to prevent stall, or ground impact. There's also some talk about the crew ignoring the failure of the altimeter, but I'm not sure if that concerns the faulty ground level indication or maybe an earlier failure warning.

The same altimeter had failed on 2 recent flights, it seems. Right side was working correctly. Pilot in control was new to 737, but experienced pilot in other seat, and they were flying a "rushed approach".

Preliminary conclusion: crew reacted too late to events caused by faulty altimeter.

English article about the preliminary findings:
http://news.bbc.co.uk/2/hi/europe/7923782.stm

Larry Jacks
2009-Mar-04, 10:00 PM
At aviation safety meetings, they commonly talk about the chain of events that lead up to an accident. It's rarely a single thing that results in a crash. If any of the events in the chain is prevented, so is the crash.

From the preliminary findings, the chain appears to be an inexperienced crew member, a faulty radio altimeter that led to power reduction, and a rushed approach. Distraction during the approach caused by the faulty radio altimeter might also be part of the chain.

mahesh
2009-Mar-04, 10:18 PM
thanks for the link, slang...i hadn't seen it

..and thank you too, Mr Jacks, for your informed explanations / observations / commentary

slang
2009-Mar-04, 10:26 PM
Yup... and different interested parties are already putting emphasis on that part of the chain that makes "their" guys come out best. Not to mention the many CT forum worthy comments. The full report should be interesting, especially wrt to cockpit situation, as you mentioned. AFAIK that part of the investigation wasn't published yet.

What some 'experts' are questioning is that only one wrong altimeter reading could cause the autopilot to go into 'landing mode', if that is what happened. "No single sensor should cause that". Have to say that part surprised me too, wonder if there was more going on.

jokergirl
2009-Mar-05, 12:15 PM
That's interesting. I always thought that the autopilot was supposed to turn off if the signals it received were mismatched/indicated a fault.

Anyone who knows more about how those landing approach algorithms work?

;)

geonuc
2009-Mar-05, 01:05 PM
..and thank you too, Mr Jacks, for your informed explanations / observations / commentary
Yes, Mr. Jacks is someone I look to for aviation-related insight. Mugaliens, too.

Larry Jacks
2009-Mar-05, 10:51 PM
From Aviation Week & Space Technology, Boeing Warns of Possible 737 Altimeter Fault (http://www.aviationweek.com/aw/generic/story.jsp?id=news/ALT030509.xml&headline=Boeing%20Warns%20of%20Possible%20737%20Al timeter%20Fault&channel=comm):

Boeing is advising operators of all 737-series and BBJ aircraft to carefully monitor primary flight instruments and not engage autopilot/throttle systems during approach and landing in event of a radio altimeter malfunction.

...

The initial accident findings, issued the same day, indicate the Dutch are focusing on the link between radio altimeter deviation and the autothrottle system as the possible cause of the landing accident.

Based on flight data recorder readouts, investigators determined that all was normal onboard Flight 1951--until the aircraft reached 1,950 feet during its final approach to Runway 18R with 135 people onboard.

At that point, the radio altimeter readout on the captain's (left) side suddenly switched to -8 feet. The altimeter, interpreting the 737 to be just a few feet above touchdown, commanded the autothrottles to power down and configure for landing.

The "landing gear must go down" warning signal alerted the crew to the problem, but data indicate the signal was not regarded as a problem, according to the prelminary report.

The 737-800 responded to the command, decelerating to minimum flying speed, with a stall warning sounding at 150 meters (490 ft.). The flight crew applied full power, but the aircraft was too low to allow recovery. The aircraft hit the ground traveling at 175 kilometers (94 knots) airspeed about 1.5 km. north of Schiphol. Normal landing speed is 260 km. or 140 kt.

Enormous braking forces--in part caused by the nose wheel becoming embedded in the ground--caused the 737 to break in three parts, with its tail, landing gear and engines detaching. Nine of the 135 onboard were killed, including the flight crew.

The deviation occurred only on the captain's (left) radio altimeter, according to the Dutch initial report, which also states that the malfunction had occurred twice previously, both times during landing. However, it was unclear from the report if the events occurred on the same aircraft.

slang
2009-Mar-06, 12:23 AM
Thanks, Larry.

When looking at www.onderzoeksraad.nl, the website of the entity investigating aircrashes here, the page showing completed investigations (http://www.onderzoeksraad.nl/index.php/onderzoeken/afgerond/sector/luchtvaart/)ends with a Fouga Magister mishap in august 2007. If that's the yardstick, we might have to wait until summer 2011 before the investigation is closed. I assume it won't be published before closing :/

slang
2010-May-06, 12:44 PM
Well, I guess they were a little quicker than anticipated, final report published a full two summers earlier!

The newspaper report about the publication indicates several causes coming together ending in disaster:
- Pilot error: crew was too late in noticing that the descent was too quick, should have initiated a go-around.
- Pilot error: crew did not adequately respond to recover from the descent
- ATC error: they instructed the crew to make a turn, but did not timely instruct to descend. This resulted in a descent too high over glidepath, make it more difficult for crew to notice something was amiss
- Boeing error: Boeing knew for years about the problems with the altimeter, but it was never seen as a safety risk. Other flights having the same failure always managed to land, and the altimeter problems were often not even reported. Had more reports reached Boeing, they might have reassessed the risk.

Haven't read the report itself yet, so I don't know if the newspaper accurately depicts what's in it, nor if my summary of that is correct.

Crashed during approach, Boeing 737-800, Amsterdam Schiphol Airport (http://www.onderzoeksraad.nl/en/index.php/onderzoeken/Neergestort-tijdens-nadering/#rapporten)

Turkish Airlines, Crashed during approach, Boeing 737-800, Amsterdam Schiphol Airport (http://www.onderzoeksraad.nl/docs/rapporten/Rapport_TA_ENG_web.pdf) (PDF, 2 MB)

Dutch page with same info, and report in Dutch:
Turkish Airlines, Neergestort tijdens nadering, Boeing 737-800, Amsterdam Schiphol Airport (http://www.onderzoeksraad.nl/index.php/onderzoeken/Neergestort-tijdens-nadering/#rapporten)

ETA: BBC News article: Pilot error in Turkish Airlines crash (http://news.bbc.co.uk/2/hi/europe/8664565.stm)

adapa
2010-May-07, 03:33 PM
Mugaliens and Larry Jacks are definitely right about the fact that it takes a chain of events in order to break through the multiple layers of protection and cause an accident.

On that note, I suspect that automation dependence/overuse is a link in this chain of events. As we all know, even the most sophisticated autopilots/autothrottles have their limitations. An automation dependent pilot will allow the automation to take the aircraft into a bad situation in the belief/hope that it will recover itself. Automation dependence/overuse can also include the failure to monitor what the aircraft is doing in a critical phase of flight simply because the pilot knows that the autopilot is flying.

I suspect that this is the case because according to the preliminary report (http://www.onderzoeksraad.nl/docs/rapporten/Prelimenary_engels.pdf), the pilots allowed the airspeed to drop 34 knots below their final approach airspeed before they intervened (assuming that they did). During this phase of flight, the pilot flying should have had his hands on the yoke (in this case) and the throttles and should be ready to disengage the autopilot and autothrottles if necessary. Even if he left the autothrottles engaged, it takes very little force to manually override the autothrottles on a B-737 or any other boeing airplane. This leaves me to wonder if he had his hand on the throttles as he should, or if he was even paying attention.

slang
2010-May-08, 12:09 AM
Yes, several key 'ingredients' of this crash probably happen every day. Only when all the problems occurred at once did the crash happen.

Automation dependence/overuse may have played a part, but the situation is quite complicated by several factors. I suggest reading the first 10 pages or so of the final report (post #33). The pilots were not and could not be aware of all details, they were overburdened due to several procedures not being adhered to, the captain was busy supervising the first officer, and it appears that the correct response to the stickshaker (applying throttle) was undone by the autothrottle, something apparently missed because the captain took over the controls (not sure if I understand the latter part correctly yet).