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Atlas Air 767 down/Texas

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Atlas Air 767 down/Texas

Old 1st Mar 2019, 18:53
  #221 (permalink)  
 
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Originally Posted by DaveReidUK View Post
Not necessarily.

If, for example, the forwardmost ULD hadn't been securely locked down, but those behind had, then the problem wouldn't have been apparent on take-off, but on descent.

We're not talking about an accident like Bagram where the cargo moved aft.

Impossible. Not enough moment arm for an attitude such as that.
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Old 1st Mar 2019, 18:59
  #222 (permalink)  
 
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Sudden significant negative G onset would certainly cause confusion if not expected.
Can anyone estimate the neg G that could be experienced from the traces posted in this thread.
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Old 1st Mar 2019, 19:26
  #223 (permalink)  
 
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From the NTSB Twitter feed:

NTSB has recovered the cockpit voice recorder from the cargo jet that crashed in Trinity Bay in Anahuac, TX. CVR being transported to NTSB labs in DC and will be evaluated when it arrives.


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Old 1st Mar 2019, 19:46
  #224 (permalink)  
 
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Originally Posted by IcePack View Post
Sudden significant negative G onset would certainly cause confusion if not expected.
Can anyone estimate the neg G that could be experienced from the traces posted in this thread.
I tried to guesstimate the negative g forces, but that would require the exact time interval from the traces, which is not entirely clear:
1g would take the aircraft from 6000ft to ground in 19 seconds (sqrt(6000/16))
2g would take the aircraft from 6000ft to ground in 14 seconds (sqrt(6000/32))
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Old 1st Mar 2019, 19:48
  #225 (permalink)  
 
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There is also the CRJ200 in Sweden that plunged into the ground in a similar fashion. One of the IRUs malfunctioned but instead of removing the attitude all together it displayed incorrect attitude information.
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Old 1st Mar 2019, 20:29
  #226 (permalink)  
 
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Originally Posted by 172_driver View Post
There is also the CRJ200 in Sweden that plunged into the ground in a similar fashion. One of the IRUs malfunctioned but instead of removing the attitude all together it displayed incorrect attitude information.
This accident happened in the dark in the middle of the night, starting at about 33,000 feet. No moon either if I recall. The crew was preparing decent or some other task so they had some lights on in the cockpit. The result was that they had very little to no outside visuals.

When the erreonous high pitch attitude showed up on the fligth display of the PF he didnt cross check with the PM's display, instead he almost instantly pushed control column forward reaching negative G as high as -1G.
VMO at 315 knot was exceeded 17 sec after onset. At 30 sec after onset IA was passing 400 knots and altitude was 24,000 feet. Crashed at near supersonic speed at around -80 degrees pitch and got completely pulverized. It took about 120 sec from onset at 33,000 feet until crash.
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Old 1st Mar 2019, 20:33
  #227 (permalink)  
 
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Originally Posted by 172_driver View Post
There is also the CRJ200 in Sweden that plunged into the ground in a similar fashion. One of the IRUs malfunctioned but instead of removing the attitude all together it displayed incorrect attitude information.
On the captains ADI, yes. Not on the other two.
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Old 1st Mar 2019, 20:34
  #228 (permalink)  
 
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Originally Posted by GordonR_Cape View Post
I tried to guesstimate the negative g forces, but that would require the exact time interval from the traces, which is not entirely clear:
Correct. While you can plot a reasonably accurate profile (altitude vs horizontal position) from the FR24 data, you can't reliably derive anything that's time-dependent as the timestamps (added to the ADS-B data by FR24) are all over the place.

Anyone who doubts that is invited to try to calculate groundspeed by dividing the distance between two successive plots by the interval between the associated timestamps.
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Old 1st Mar 2019, 20:47
  #229 (permalink)  
 
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On the captains ADI, yes. Not on the other two.
It was enough to cause the end result.

I don't know if 3591 was in visual conditions or not. The only camera footage I have seen show a rather hazy atmosphere.

It was just one idea of many possible.
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Old 1st Mar 2019, 20:56
  #230 (permalink)  
 
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Salute!
Seems someone elsewhere mentioned that the two recorders were within 10-15 feet of each other vertically and maybe 20 feet horizontally.
So finding the FDR now seems imminent.
Gums.......
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Old 1st Mar 2019, 21:10
  #231 (permalink)  
 
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Here's some discussion of 767 stab trim from PPRuNe 15 yrs ago - PPRuNe.org/tech-log/145022-unschedule-stab-trim-b767.html (I can't post links)
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Old 1st Mar 2019, 22:19
  #232 (permalink)  
 
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at a previous employer we had the elevator feel system freeze due to leaking toilet moisture, and the crew were unable to move the elevators (both columns) during initial level off arriving at destination, they used the stabilizer, after a short while the system unfroze due to warmer air and the airplane returned to ops normal...happened to only one aircraft, twice..system was repaired, never happened again..
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Old 1st Mar 2019, 23:00
  #233 (permalink)  
 
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Red face

Originally Posted by mryan75 View Post
God i wish this forum required a pilot certificate number for registration. Or an IQ test.
Frankly, I'm surprised the former is not a fundamental requirement of forum participation. I'm afraid the latter would exclude me!
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Old 2nd Mar 2019, 00:36
  #234 (permalink)  
 
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An update from the Chambers County Sheriff's Office Facebook page.

Today the Houston Police Department Dive Team continued to be a critical part of the recovery efforts of flight 3591 in Trinity Bay. They have been instrumental in this operation to help try and recover Captain Ricky Blakely of Indiana.

The cockpit voice recorder was recovered this afternoon and was transported by the Chambers County Sheriff’s Office to Houston Intercontinental Airport to be flown to Washington, DC, for immediate analysis.

Sheriff Hawthorne would like to thank everyone that has worked tirelessly on this recovery operation.

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Old 2nd Mar 2019, 03:12
  #235 (permalink)  
 
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I think KAL had two crashes that were caused by following bad attitude displays. B747 and an MD11.
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Old 2nd Mar 2019, 04:09
  #236 (permalink)  
 
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Originally Posted by N1EPR View Post
I think KAL had two crashes that were caused by following bad attitude displays. B747 and an MD11.
i think Air India as well late 70s in departure from BOM
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Old 2nd Mar 2019, 05:24
  #237 (permalink)  
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Originally Posted by N1EPR View Post
I think KAL had two crashes that were caused by following bad attitude displays. B747 and an MD11.
Just one the 744F, the MD11 you speak of the CA was 1500’ high and pushed nose over to sharply and drove A/C into ground from 4500’
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Old 2nd Mar 2019, 05:26
  #238 (permalink)  
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KAL lost the B747-200F at EGSS on 22 Dec 1999 by memory. It had a Capt's ADI failure in roll axis only. The only person who knew what was happening was the Flt Eng, and he resigned to his fate on the way down. The CVR is sobering, as was how close it got to the village. The other ADI and standby were fine until they got mussed up by England's green and pleasant land.

The mega death 2.0 was not caused by any attitude indication failure. The accident report by the state of incident is nonsense, and did not make any sense to the CVR or the radar data which is all that survived. The DFDR was taken out by the APU... The FO was aware of the event as it developed. The underlying causal factor is common on many other aircraft, however, the 2.0 at modest weights can have a wild ride in certain circumstances. Paradoxically, having good performance can result in not having any performance... on 15 Apr 99, the crew got caught out by the interplay of the AP and ATS in high rate events. The logic of the system has been changed since then, but the same sort of interplay still occurs on Boeings to this day. Airbus, this is one event that would not occur in your airplanes, you have other matters to deal with, like full thrust TOGA which adds so much fun to the event. HL7373 was more or less wings level from the event to impact. It did stall twice in the event, once at TOC, and once in the recovery. The last high speed stall probably would have made no difference, the attitude required to meet the available data made a prompt recovery necessary before the pitch attitude had decreased to that in the mid stages of the descent. From approximately 4500' AGL, the aircraft hit the ground in just a little over 16 seconds, from a low speed as recorded by both the radar plot and by the spectral analysis of cockpit wind noise. The behaviour of the autothrottle was identifiable by spectral analysis of the CVR, which showed that where the engine signal was lost due to ambient noise, the 400Hz lines and their harmonics showed the response of the CSD which has a slight delay to the changes in engine RPM; increasing N2 gives an initial overspeed of the CSD which shows as a shift of the 400Hz line, and vice versa for the thrust reduction case. The cockpit broadband noise also provided an SPL solution for speed, which made the modelling of a reasonable flightpath possible in conjunction with the calls of speeds, and the radar data which was pretty sketchy itself. When you are flying your non Bus aircraft, pay some attention to high rate altitude captures with AP and ATR engaged, as during the altitude capture the aircraft is pitching to a rate to achieve the level, which may or may not be within the energy capability of the aircraft. Opposite occurs in a high rate descent capture of an altitude, if you have the boards out, then retracting them once the altitude has been captured will result in a speed excursion dependent on the sink rate and speed at the time of alt cap.

Capturing an altitude from a zoom climb, where you happen to have traded speed for increased vertical rate needs to be carefully monitored, as you may not have enough thrust left to fly the path that is now commanded by the APFD, and you could end up with a reducing airspeed if not intervened.

Filejw: I assure you from hundreds of hours of reviewing 16 seconds of audio, that the crew did not dive the aircraft into the ground, it stalled at TOC. The CAAC report was and is nonsense, and did not match the CVR or radar data. The FO was rather insistent in the last seconds of his life about raising the attitude that the aircraft had achieved in the post stall, and which had a hesitation mid way down from the secondary stall which was evident on the CVR. The hypothesis of a simple push forward from the speed of 240KIAS (by memory that was assumed) but did not match the radar data) was not borne out by kinematic reconstruction or by simulator trials; simply put, you cannot get the plane from Point A to the known Point B in the required attitude at impact, time or distance, which I was also involved in. FYI, the simulator was odd in its own right, we demonstrated 6000FPM + rate of climb in full stall conditions which didn't appear to match either the QTG or the plane itself. The MD11 was an acquired taste; it had more than it's share of issues on landing, from a high approach speed as a freighter, coupled with it's relaxed longitudinal stability which LSAS assisted to some extent. The 10 was a very nicely harmonised plane,

The EGSS aircraft was a -2B5F, (MSN448, HL7451 KAL8509) not a -400. Both of these were messes to clean up.

Last edited by fdr; 2nd Mar 2019 at 05:45. Reason: corrected date 23>22
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Old 2nd Mar 2019, 06:34
  #239 (permalink)  
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Originally Posted by ironbutt57 View Post
at a previous employer we had the elevator feel system freeze due to leaking toilet moisture, and the crew were unable to move the elevators (both columns) during initial level off arriving at destination, they used the stabilizer, after a short while the system unfroze due to warmer air and the airplane returned to ops normal...happened to only one aircraft, twice..system was repaired, never happened again..
Could please explain how leaking toilet water can get into Pitot Static system of the 767 Elevator Feel Computer.
Having recently removed and replaced a faulty Feel Computer and carried pitot static checks on this system I don’t think this is possible.
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Old 2nd Mar 2019, 08:19
  #240 (permalink)  
 
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I believe he was suggesting that water can freeze up the screw jacks so that the hydraulics can’t turn them.

I experienced that with the flaps stuck up on arrival after a departure in heavy rain. We were just beginning the checklist when things thawed out and in another minute were working normally.

In this case, I would expect that a frozen stab problem would have occurred earlier as the trim changed with IAS during descent.
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