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N72EX (Kobe Bryant) Crash Reconstruction with new ATC Audio

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N72EX (Kobe Bryant) Crash Reconstruction with new ATC Audio

Old 30th May 2020, 11:52
  #21 (permalink)  
 
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How accurate is the airspeed readout in the video?
If he was coupled up in the climb and allowed the airspeed to bleed below 60kias, the autopilot heading reference would switch from roll to yaw. Could explain the sudden left turn and disorientation.
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Old 30th May 2020, 12:01
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Yep, for SPZ-7000 it's 60 KIAS.
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Old 30th May 2020, 12:19
  #23 (permalink)  
 
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Originally Posted by TIMTS View Post
...Could explain the sudden left turn and disorientation.
I don't believe that theory. If HDG mode was engaged the bank angle won't exceed 20 degrees by system design. I think he had quite a bit more than 20 degrees left bank towards the end. I would be very surprised if the pilot had made any use of the autopilot. Regrettably.
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Old 30th May 2020, 13:58
  #24 (permalink)  
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Originally Posted by TIMTS View Post
How accurate is the airspeed readout in the video?
The speeds shown in the video are what I would call kinematic speeds (combination of ground speed and vertical velocity from GPS/ADS-B) The speeds shown do not reflect any wind (which I assumed were calm the entire time based upon the METAR at VNY). They also do not reflect effects of air density on indicated air speed. Given those caveats, I think the speeds are pretty close to both TAS and IAS. As a sanity check, the lowest ground speed reported in the flightradar24 ADS-B data for the duration of the video is 109 knots (I would give a link to the data, but I don't yet have that privilege "www.flightradar24.com/blog/wp-content/uploads/2020/01/N72EX-Granular-Data.csv"). I think the aircraft was well above 60 knots the entire time.

I also note from that ADS-B data the altitude, ground speed, rate of climb, bearing, or turn rate are never constant for the duration of the video. Would one of those be mostly constant, for at least a little while, if the autopilot was engaged?
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Old 30th May 2020, 15:08
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ATP and CFII aside, from the information Iíve seen this pilot flew VFR in a predominately VMC environment. It appears recurrent training/checking was accomplished in the actual aircraft using a view-limiting device and not in a simulator. I suspect he maintained basic instrument currency by performing the minimum requirements every 6 months during his 135 checks. Given these supposed circumstances, an IIMC recovery would be at best, an accident waiting to happen.

Also, consider how he achieved the initial rate of climb.
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Old 30th May 2020, 16:37
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Originally Posted by airplanecrazy View Post
...Does pressing the GA button activate the autopilot if the autopilot is currently off, or would the autopilot also have to be turned on to actually command the aircraft?
The S76 is always flown with both AP's on. The AP's can be in stability augmentation mode or attitude retention mode. For the flight director to control the aircraft the AP's must be in attitude retention mode with the force trim ON. The S76 should be flown in attitude retention mode, and I would be very surprised if this aircraft was being flown in stability augmentation mode. Therefore, one button press on the flight director would have given safe control of the aircraft to George (assuming FD2 was the active flight director).
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Old 30th May 2020, 16:41
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Originally Posted by [email protected] View Post
Yes, that report is classic saturation trying to deal with real IMC as a single pilot.

What can make it worse is engaging an autopilot that has its own limitations and tends to meander about whatever datum was set - this is especially true of 3 axis APs that have to use cyclic pitch to do things like hold ALT or VSI - they are slow, lagged to reduce control inputs and don't deal with turbulence well.

Unless you have experienced it to the point you were scared, it is difficult to explain how powerful the spatial disorientation illusions can be, convincing you that you are in a turn to the right (for example) when you are actually close to wings level and causing you to push left bank because it 'feels right'.

Constant practice in actual IMC conditions is the only way to prepare you for IIMC - or perhaps try teaching students to fly IMC, that sorts you out when they screw it up
Having SPIFR experience in the 135, and many a hour in the 135 simulator (flying and observing), I surmise the pilot lost control of the aircraft during his reconfiguration for the missed approach.

First, it appears the controller violated ATC procedures by vectoring the aircraft in violation of the recommended distance/angle from the approach gate. This is what precipitated the accident. At his point, I guess the pilot failed to arm the GS, or armed the GS after passing through it. This would explain why the aircraft never descended.

Second, when the pilot realized the AP didn’t capture the GS, he requested a missed approach. However, I believe he may have been in a slightly confused state of mind (unusual position and circumstances). He was then instructed to perform the published missed, which suddenly increased his workload. I would guess he hadn’t familiarized himself with the missed approach instructions, and therefore needed to quickly find/read them. This also helps to explain the unwarranted climb at this time. Most pilots would (eventually) place the FMS into NMS/GPS mode in order to fly this missed procedure, which requires a reconfiguration. I suspect the pilot may have inadvertently disconnected the AP at this point. Disconnecting is an easy mistake, especially if one doesn’t perform the reconfiguration in an orderly fashion. With the sudden, unexpected AP decoupling, and a slightly confused state, I expect the aircraft quickly lost airspeed, stability and the pilot lost control.

An ATC procedural error combined with pilot task saturation and FMS/AP misconfiguration followed by the pilot’s inability to perform an unusual attitude recovery resulted in this crash.

As always, I could be completely wrong.
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Old 30th May 2020, 16:46
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Originally Posted by JimEli View Post
..As always, I could be completely wrong.
Yes you are. The pilot was not on a PROC so there was no GS to capture. He was not being vectored by ATC, he was flying VFR OCTA following a major highway.
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Old 30th May 2020, 16:55
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Originally Posted by JimEli View Post
..I expect the aircraft quickly lost airspeed, stability and the pilot lost control..
Nope, the aircraft was at high speed immediately prior to the accident sequence. The pilot was in control, he just lost situational awareness.
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Old 30th May 2020, 17:39
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Originally Posted by gulliBell View Post
Yes you are. The pilot was not on a PROC so there was no GS to capture. He was not being vectored by ATC, he was flying VFR OCTA following a major highway.
he was talking about the EC135 accident report quoted earlier
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Old 30th May 2020, 18:15
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I wonder what position the NTSB found the force trim release switch?
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Old 30th May 2020, 18:16
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Originally Posted by gulliBell View Post
Yes you are. The pilot was not on a PROC so there was no GS to capture. He was not being vectored by ATC, he was flying VFR OCTA following a major highway.
Take your finger off the trigger, you're scaring everybody.
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Old 6th Jun 2020, 13:23
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I have started a g-force analysis of the flight using a program called "Tacview" and what I currently see in my model is that from 17:45:12 (after the sharp turn is established) to 17:45:22 (about when the pilot finishes saying he intends to climb to 4000), the combination of turn and acceleration downward appear to give about 0.9 - 1.1g down in the seat with very little lateral (side to side) or longitudinal (backward and forwards) g's. This is very preliminary, but I would like like to know if that even sounds possible to you all? I can reproduce a similar effect flying the X-Plane S76 simulator, but 1) It is a not a full fidelity simulator, 2) It doesn't really tell me how it would feel in the cockpit; and 3) I don't know if a pilot would notice himself/herself making the control inputs necessary to preserve a 1G in the seat as they are descending/turning (assuming the pilot is not getting attitude information from the AI and is flying by feel). I still have a lot of work to do to be confident in these preliminary results because I am still working on my pitch/roll model, working on my filtering software to deal with GPS position gaussian error, and working on my algorithm to deal with the 25 foot quantization of altitude in the ADS-B data, but it looked interesting...

Last edited by airplanecrazy; 6th Jun 2020 at 13:43.
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Old 6th Jun 2020, 18:03
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Originally Posted by airplanecrazy View Post
(assuming the pilot is not getting attitude information from the AI and is flying by feel).
A fundamental concept of successful IMC flying is understanding the fact that you cannot fly by feel. If there's no AH, then flying off the remaining instruments is possible, however if a pilot's just looking out the window trying to regain references (or ignoring the instruments in some other way), they won't be flying for much longer.
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Old 7th Jun 2020, 09:41
  #35 (permalink)  
 
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Originally Posted by airplanecrazy View Post
... the combination of turn and acceleration downward appear to give about 0.9 - 1.1g down in the seat with very little lateral (side to side) or longitudinal (backward and forwards) g's. This is very preliminary, but I would like like to know if that even sounds possible to you all?
What would you like to know whether it is possible?

To fly wth 0.9g to 1.1g, and little lateral or longitudinal acceleration? I would say that is the aim. The lateral and logitudinal g's normal only come in at the moment of contacting terra firma (i.e., hard landing or crash).
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Old 7th Jun 2020, 13:29
  #36 (permalink)  
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Originally Posted by ApolloHeli View Post
A fundamental concept of successful IMC flying is understanding the fact that you cannot fly by feel. If there's no AH, then flying off the remaining instruments is possible, however if a pilot's just looking out the window trying to regain references (or ignoring the instruments in some other way), they won't be flying for much longer.
Originally Posted by Hot and Hi View Post
What would you like to know whether it is possible?

To fly wth 0.9g to 1.1g, and little lateral or longitudinal acceleration? I would say that is the aim. The lateral and logitudinal g's normal only come in at the moment of contacting terra firma (i.e., hard landing or crash).
I see that I did not phrase my question well, so I will try again The hypothesis I am exploring is that the pilot's attention could have been diverted away from the attitude indicator from 17:45:12 - 22 and that he "subconsciously" applied control inputs while distracted to maintain a 1g trajectory for those 10 seconds, even though the helicopter was banking and descending at the end of that period. My question is does the hypothesis seems possible to actual pilots? I have no experience to judge whether it would have required more than "subconscious" concentration from the pilot to achieve that trajectory, or to know if the pilot would have noticed making those control inputs (e.g. it would require the cyclic to be in an unexpected position).
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Old 7th Jun 2020, 13:53
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Edit:- Ha! Our posts crossed:-)

Airplanecrazy, who did the AMAZING video reconstruction says:-

Originally Posted by airplanecrazy View Post
the combination of turn and acceleration downward appear to give about 0.9 - 1.1g down in the seat with very little lateral (side to side) or longitudinal (backward and forwards) g's. This is very preliminary, but I would like like to know if that even sounds possible to you all?
I don't know if a pilot would notice himself/herself making the control inputs necessary to preserve a 1G in the seat as they are descending/turning (assuming the pilot is not getting attitude information from the AI and is flying by feel).
Since no one competent appears to have answered I will give it my best!?

I have done zero instrument flying, some other flying and I even had a helicopter lesson:-)

Your statements above seem reasonable to me. As the g tended to increase due to the turn the pilot could well have compensated automatically with a bit of forward cyclic.

In fact, thinking further, without some aft cyclic the aircraft may well have maintained 1g all by itself. To get more than 1g, up collective (+power) would be required and also aft cyclic to maintain the flight path as a level turn.

Perhaps all that was required was a little bit of roll input or perhaps the helicopter's natural instability would have been sufficient?

Maybe someone who understands this properly can respond to airplanecrazy? I have no knowledge of any autopilot or stability systems.

The reconstruction is very powerful and the scenario presented suggests that the pilot became distracted or maybe had a medical issue.

In addition to the amateur ADS-B collections there are I believe official ones. They may add to the available data and are likely to have proper timestamps. There are new satellite ADS-B data gathering systems too. I believe at least one is in pre-production testing and that they provided the data that persuaded Boeing to ground the 737 MAX. Boeing seemed to feel it safe (for them) to discard as irrelevant the amateur-collected material that showed a flight path eerily similar to the LyonAir crash.

https://www.flightradar24.com/blog/s...radar24-users/

Last edited by jimjim1; 7th Jun 2020 at 14:05.
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Old 7th Jun 2020, 14:39
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In straight and level constant speed flight you experience 1G, just as if you were standing on the ground not moving - all forces are in balance.

If you roll into and maintain a steady state turn while maintaining height you will experience an increase in steady state G - 1.4 G at 45 deg AoB and 2 G at 60 deg AoB because the you are accelerating towards the centre of the turn.

As Apolloheli pointed out, you can't fly IMC by feel because of the lack of the visual cues your brain needs to orientate itself and the fact that acceleration in all axes affects the vestibular organs of your inner ear causing powerful sensations of pitching, rolling or yawing.

Whilst it is possible to fly instruments without an AH/AI it takes practice and is far more likely to end in tears than when using an AH/AI.

In the thread accident, all we know is that what he wanted to do with the helicopter isn't what the helicopter was actually doing - typical symptoms of disorientation.

If you end up IMC when you weren't expecting to and don't lock straight into an instrument scan, things are going to go wrong quite quickly - if you have the aircraft trimmed straight and level and don't move the controls apart from raising the lever a little to initiate the climb then you might survive to VMC on top.

If you go into cloud already in a turn you are halfway to the crash if you don't lock onto instruments and if this happens while you are moving your head around looking for external references you have a bullet in the chamber and your finger on the trigger.

For those that haven't experienced it, I cannot explain how powerful the illusions of bank can be - the leans - and how easy it is to end up in a spiral descent. If you have the height and awareness to recognise the situation you can recover it with good instrument flying skills and I have had to take control from disorientated students in this configuration many times in cloud. If you don't have the height and awareness you are doomed.
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Old 7th Jun 2020, 15:14
  #39 (permalink)  
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Originally Posted by jimjim1 View Post
Edit:- Ha! Our posts crossed:-)
Airplanecrazy, who did the AMAZING video reconstruction says:-
Thanks for the kind words!

Originally Posted by jimjim1 View Post
In addition to the amateur ADS-B collections there are I believe official ones. They may add to the available data and are likely to have proper timestamps.
I sent a FOIA request to the FAA for the ADS-B data they have. In discussions with the FOIA officers, I think there is a good chance I will get it.
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Old 7th Jun 2020, 16:11
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For those that haven't experienced it, I cannot explain how powerful the illusions of bank can be - the leans - and how easy it is to end up in a spiral descent.
i agree - like a lot of things itís hard to understand without experiencing it. Iíve had full blown leans three times - once in IMC and twice in VMC. The IMC encounter was after a 270 degree turn from ATC vectors, and when I rolled level it felt like I was banking the opposite direction. It required complete fixation on my scan until the felling began to dissipate. The VMC encounters were once in clear visibility above a smooth full cloud layer that had a slope to it, giving a false horizon (I assume a temperature gradient?). Secondly in hazy conditions with no visible horizon, approaching the coast, that was straight but not perpendicular to our approach, giving a false horizon. I had to revert to instruments to overcome the sensation of banking which was almost overwhelming in both cases.
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