Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

TransAsia in the water?

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

TransAsia in the water?

Old 5th Feb 2015, 02:02
  #121 (permalink)  
 
Join Date: Jul 2004
Location: Found in Toronto
Posts: 610
Originally Posted by papershuffler View Post
As mentioned at #109, I was studying the horizontal stabilisers ("h/s") earlier and thought there was a section missing on the port side.

Bearing in mind the t-tail design which distorts perspective, it's not so much the length, rather than the shape.

BBC News - Taiwan TransAsia plane crashes into river

On the third clip (taken by the car in the right lane) at 18-20s, have a look at the port side. I confirmed with a bit of modelling tonight, that the end of the stabiliser should graduate away bearing in mind perspective and the angles the plane travels through. Instead, it's 'blunter' than it should be; the tapered end part appears to be missing.

So, if part of the h/s had gone, some down force would be lost, the nose would go down, and the AOA of that wing would lower, possibly creating a spin. Does this fit the scenario?
It does look like the port side stabilizer and elevator are misshapen but it may just be some kind of an optical illusion.

Even if part of the stabilizer were missing I don't believe there is enough missing to account for what we see happen to the aircraft. To me it just looks like a stall with a wing drop.

Lowering the nose would reduce the AOA on both wings and would prevent a stall. Are you are suggesting that a smaller port side stab would reduce the AOA on only the starboard wing and cause a spin to the left? That just doesn't make any sense to me at all.



Lost in Saigon is offline  
Old 5th Feb 2015, 02:40
  #122 (permalink)  
 
Join Date: Dec 2005
Location: Wellington,NZ
Age: 63
Posts: 1,641
Originally Posted by papershuffler View Post
.....
So, if part of the h/s had gone, some down force would be lost, the nose would go down, and the AOA of that wing would lower, possibly creating a spin. Does this fit the scenario?
Nope. Firstly, regarding spinning, a reduction in AoA will reduce the likelihood of a stall/spin, not increase it. (It would appear that had the crew reduced the AoA prior to the roll commencing, the result would have been similar; it would have hit the bridge, but probably at a slightly different - and maybe less survivable - configuration. They simply didn't have the altitude to play with, and probably not the required power to prevent it.

I doubt that anything the crew did made the accident more or less survivable. They were clearly out of options, and just prolonging the inevitable (as you do. Poor buggers.) (This is called ''stretching the glide''. It didn't quite work. It often doesn't. It may have set up - inadvertently - an accident geometry that made the impact survivable for some on board. Having seen the videos, it is not the sort of accident sequence one would expect survivors from. Those few were darned lucky.)

The accident sequence was already established; the roll to the left was merely part of it.
The aircraft was already committed to crash into the river/bridge prior to any power line contact taking place.

Appears a classic stall/incipient spin to me.
Tarq57 is offline  
Old 5th Feb 2015, 02:41
  #123 (permalink)  
 
Join Date: Jan 2006
Location: US
Posts: 2,200
Post 116 - One can understand why they would stretch the glide as the terrain was as hostile as it gets.






There is no "stretch the glide" ability by going slower than your best L/D speed. Going slower reduces how far you fly.
misd-agin is offline  
Old 5th Feb 2015, 03:04
  #124 (permalink)  
 
Join Date: Jul 2013
Location: New Zealand
Age: 67
Posts: 74
Further, to stretch the glide into wind the airspeed should be increased above best LD by around half the wind speed.
Ka6crpe is offline  
Old 5th Feb 2015, 03:05
  #125 (permalink)  
 
Join Date: Jul 2000
Location: Nirvana..HAHA..just kidding but,if you can tell me where it is!
Posts: 348
Stretching the glide..yes,I was sure I mentioned that..I just can't found out where...Alzheimer's
..or Mr.Moderator!!
Yaw String is offline  
Old 5th Feb 2015, 03:06
  #126 (permalink)  
 
Join Date: Sep 2013
Location: USA
Posts: 85
There is no "stretch the glide" ability by going slower than your best L/D speed. Going slower reduces how far you fly.
This assumes that all you care about is at what point along a flat surface you will hit the ground. There are often other considerations besides best distance. Like perhaps a large chunk of concrete in your way.
core_dump is offline  
Old 5th Feb 2015, 03:12
  #127 (permalink)  
 
Join Date: Jun 2002
Location: Far East
Posts: 360
From the close in pics of the aircraft clipping the car, can anyone see if the rudder is being use - I would have expected to see a whole lot of right rudder but to me it looks central??
CDRW is offline  
Old 5th Feb 2015, 03:41
  #128 (permalink)  
 
Join Date: Feb 2012
Location: BBN
Posts: 191
May I throw a spanner in the works, Does this company use Selatar in Singapore for their proficiency checks? If so is this company one of the Asian carriers that were continuing to check their pilots in a simulator with broken rudder peddles? I know for a fact that this simulator was still been used by company's in this broken state in the second half of last year. If so did these two pilots conduct a check and pass in a simulator with broken rudder peddles?
SHVC is offline  
Old 5th Feb 2015, 04:05
  #129 (permalink)  
 
Join Date: Aug 2012
Posts: 1
From that image it is appears that the left prop was rotating at much slower rate, hence the different motion blur that both props have got on the image - it is 2-2.5 times longer on the right propeller.

If my assessment is correct, it looks like the right propeller was rotating faster - (roughly) 2 2.5 faster, than the left one.

Here - i made a small test to confirm that - the left object rotates at 2.5 times faster rate than the right one.



Last edited by Sunamer; 5th Feb 2015 at 04:39. Reason: added image
Sunamer is offline  
Old 5th Feb 2015, 04:44
  #130 (permalink)  
 
Join Date: Oct 2009
Location: usa
Posts: 67
Where do I start?

If there is damage to the port side elevator balance tab that some of you see in the video stills, where did it come from? Ground damage missed on preflight is my only guess. Even if a turbine wheel burst, it would most probably have been contained by the shroud. The engine parts would not go downstream and hit the T tail, no alignment. Prop blade? I see all four blades on both engines. Only "damage" I see prior to impact is caused by camera angle and the inherent distortion of a digital image expanded beyond the limits of its pixels. No, the aircraft was in good shape before impact.

In the best of the two dash cam videos, the aircraft appears from the left and is wings level, apparently slow, in a nose high attitude at a high rate of descent. At one point after takeoff they declared a "Mayday, engine flame out".

But at one point in the flight they had altitude (1250 feet), near sea level (fat air), and adequate airspeed. It was not that long a flight, so probably a light fuel load and well under seat capacity. The were not "heavy".

The aircraft should have been able to fly after V1 , climb and return. Minimum airspeed, no altitude, the aircraft should have been up to the task.

They pissed it all away and when they saw that they were not going clear the roadway, panicked and deep stalled the aircraft; the left wing stalled first. Lift normally generated by thrust over the wing that was absent due to the failed engine determined the direction of roll. Stalled. Not a "spin". A spin would need altitude.

The crew mismanaged a manageable incident. They "screwed the pooch". Whether it was their shortcomings or the lack of good training or training standards, is not mine to speculate. But when I transitioned to several different aircraft I was trained to "approach to stall" recovery. It wasn't till several crews actually stalled the aircraft (thankfully with sufficient altitude) that we received true stall avoidance/recognition/recovery training.
bloom is offline  
Old 5th Feb 2015, 05:02
  #131 (permalink)  
 
Join Date: Jul 2004
Location: Found in Toronto
Posts: 610
Originally Posted by bloom View Post
Prop blade? I see all four blades on both engines. Only "damage" I see prior to impact is caused by camera angle and the inherent distortion of a digital image expanded beyond the limits of its pixels. No, the aircraft was in good shape before impact.
I agree with everything you say but an ATR-72 has more than four prop blades. I suppose the photos only look like four blades due to motion blur of the dash cam video.






Last edited by Lost in Saigon; 5th Feb 2015 at 05:24.
Lost in Saigon is offline  
Old 5th Feb 2015, 05:04
  #132 (permalink)  
 
Join Date: Jun 2011
Location: Sydney
Posts: 55
Bloom you are happy to speculate that "they pissed it all away", "deep stalled" (sic), "mismanaged a manageable incident" and "screwed the pooch" on what little evidence there currently is yet it's not for you to speculate on training standards...wtf?

As for the old stretching the glide scenario, we need to consider that this probably saved those few. Turning that last bit of airspeed into momentum away from buildings and admittedly losing glide distance afterwards may have prevented a 911 type impact.
OzSync is offline  
Old 5th Feb 2015, 05:09
  #133 (permalink)  
 
Join Date: May 2001
Posts: 10,822
To deep stall it they would have had to defeat the stick pusher.

There is nothing in the alt profile to suggest that it activated
mad_jock is offline  
Old 5th Feb 2015, 05:15
  #134 (permalink)  
 
Join Date: Oct 2011
Location: Camel-Lot
Posts: 67
I think an engine failed at ~1,300 ft
Look at the graph on page 6 of this thread.
The flight lasted 3 min, 45 sec

00:00 Takeoff roll commenced
01:00 Rotate
01:45 Lower the nose, accellerate, retract flaps (maybe), all normal, autopilot may have been on
02:10 Engine fails at 1,300ft, pilots level off, airspeed decays
02:20 Wing stalls, aircraft drops 500 ft in 15 sec
03:45 Impact

I think the wing stalled in level flight after the engine failed. Maybe late going TOGA or MCT on the good engine. I think the aircraft remained stalled, or at least on the far back side of the power curve, until impact.

The crew were likely task saturated trying to secure a failed engine, turn away from terrain, and recover from a stall, almost simultaneously. Throw in GPWS alerts to add to the mix at the end. And we know from the final seconds of the video that this ATR can surely drop a wing in a stall, so the initial stall that lost them 500’ in 15 seconds may have well been similar. Very disorienting.

We all practice V1 cuts. Rarely do we practice engine failure in initial climb or in the cleanup phase, possibly in a terrain avoidance turn. My last airline had a sim scenario with engine failure at 700’ in IMC with the autopilot off. Much harder than a standard V1 cut.
MagicCarpet is offline  
Old 5th Feb 2015, 05:16
  #135 (permalink)  
 
Join Date: Jan 2008
Location: North England
Posts: 29
Apparently one of the air stewardesses who survived was also on board the last crash in July 2014. Lucky girl, depending on whether you're a glass half full kind of person! Not sure how anyone could return to work after going through this twice though.

58 souls, 15 survivors, 12 stilll missing.
McWho is offline  
Old 5th Feb 2015, 05:18
  #136 (permalink)  
 
Join Date: Nov 2005
Location: JAKARTA
Posts: 16
as they never reached VFTO they didn't complete memo items ( SHUT OFF engine )....if engine 1 was not fully flamed out ...propeller was still spinning.
cris95123 is offline  
Old 5th Feb 2015, 06:16
  #137 (permalink)  
ZFT
N4790P
 
Join Date: Jun 2002
Location: Asia
Age: 70
Posts: 2,055
May I throw a spanner in the works, Does this company use Selatar in Singapore for their proficiency checks? If so is this company one of the Asian carriers that were continuing to check their pilots in a simulator with broken rudder peddles? I know for a fact that this simulator was still been used by company's in this broken state in the second half of last year. If so did these two pilots conduct a check and pass in a simulator with broken rudder peddles?
Interesting comments as Selatar in Singapore is in fact ATR's own training Center and until last month was the only operating 72-600 simulator within the region. Would find it somewhat difficult to accept an aircraft manufacturer would compromise themselves this way!
ZFT is online now  
Old 5th Feb 2015, 06:27
  #138 (permalink)  
 
Join Date: Dec 2005
Location: Finland
Posts: 242
It does look like the port side stabilizer and elevator are misshapen but it may just be some kind of an optical illusion.
Another explanation is that when the elevator is in full-up position, the mass balance horns protrude from the shape quite prominently. The starboard side seems to look similar.

In that situation, maximum pull would be a natural, if not optimal, pilot action.
snowfalcon2 is offline  
Old 5th Feb 2015, 06:28
  #139 (permalink)  
 
Join Date: Mar 2010
Location: on a blue balloon
Posts: 339
Fishy ...

Can't spell pedals and doesn't know it's Seletar not Selatar.
oldchina is offline  
Old 5th Feb 2015, 06:34
  #140 (permalink)  
 
Join Date: Feb 2012
Location: BBN
Posts: 191
Do apologize for my spelling as I was on a IPhone and in a rush. But if anyone of you do the research you will find that it is fact that the sim was still operating with inoperative rudder pedals for up to 4-6 weeks. ATR were still allowing companies to use it in this condition.
SHVC is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.