Sikorsky S-76B crash (Kobe Bryant) 4

[MacGyverS2000]

Anyone heard any technical details on the cause yet?

https://www.nbcconnecticut.com/news...-that-killed-kobe-bryant-four-others/2214898/

Dan - Owner

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[Kestrel42]

The pilot was IFR rated and recently retrained, but interviews with other pilots he flew with indicate he did not have experience flying in fog or cloudy conditions. You may be qualified AND current and still simply lack direct experience with those conditions. It doesn’t take very long for things to go south once you become disoriented.

 

[3DDave]

Apparently the big problem is changing the orientation of the head during accelerated flight producing an incorrect evaluation of the actual acceleration; it seems more than coincidental that the flight deviated at about the same time he would go from looking forward to turning and looking down to change the frequency. While he had done this fine several times before, this may have been the first time he did it on that flight in white-out conditions, so he'd have no horizon or road as reference.

If he had initiated the turn to avoid clouds and then looked down and to the side to change the frequency that might have been enough to initiate the crash sequence. It's one thing to enter white-out straight and level and maintain that; doing so while turning and then complicating the situation may have been too much.

 

[Alistair_Heaton]

Yep it always bites even when your used to it.

That's why commercial air transport we have two pilots one flies/manages the flight path and machine and the other deals with radios and the rest.

One of the first lessons we teach pilots is

Aviate, navigate then communicate.

 

[btrueblood]

Why fly treetops when clear air was just a few hundred feet up?

 

[3DDave]

To avoid losing VFR during a descent back through the clouds and ending up exactly where he ended up.

 

[moon161]

Have helicopters got a spiral dive mode that feels ok by the seat of the pants (resultant vector normal to the cockpit floor) but is headed into the ground?

 

[LittleInch]

That NTSB report is as usual full of information.

It states the last transmission was that the pilot was climbing up to 4000 ft to make himself visible to radar and be above the cloud layer.

The plot of the last part of the flight seems to bear this out with the helicopter climbing steadily before then for reasons unknown starting a banking dive to the left.

Would it really be that hard to maintain level climbing flight in a straight line??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[moon161]

The spiral dive is a mode covered in the flight dynamics course I took [edit, Thank You Bill Rae, UB emeritus], a coordinated descending turn. Absent a pilot, a paper airplane trimmed for straight and level flight can enter it if perturbed, IIRC. [edit- I don't have enough of a clue about helicopter stability and control to say if this flight mode directly applies to a helicopter.]

Edit: Spiral dive flight mode:

http://www.skywalker.ca/Flying_Stories/Bob_s_Stories/SpiralDive.PDF

This also relates to the graveyard spiral, where for a passenger or pilot, absent horizon cues, nothing is going to seem wrong because the net vector is normal to the floor when flying this coordinated descending turn. This excerpt talks about how straight and level can seem to be the deviation if the inner ear is spinning long enough.

The graveyard spiral is associated with a return to level flight following an intentional or unintentional prolonged bank turn. For example, a pilot who enters a banking turn to the left will initially have a sensation of a turn in the same direction. If the left turn continues (~20 seconds or more), the pilot will experience the sensation that the airplane is no longer turning to the left. At this point, if the pilot attempts to level the wings this action will produce a sensation that the airplane is turning and banking in the opposite direction (to the right), a sensation commonly known as "the leans". If the pilot believes the illusion of a right turn (which can be very compelling), he/she will re-enter the original left turn in an attempt to counteract the sensation of a right turn. If the pilot fails to recognize the illusion and does not level the wings, the airplane will continue turning left and losing altitude.[5] Because an aircraft tends to lose altitude in turns unless the pilot compensates for the loss in lift, the pilot may notice a loss of altitude. The absence of any sensation of turning creates the illusion of being in a level descent. The pilot may pull back on the controls in an attempt to climb or stop the descent. This action tightens the spiral and increases the loss of altitude.[6]

The solution, of course, is for the pilot to consciously override the brain's imperative to judge physical altitude on the basis of signals from the vestibular, and rely solely on the visual cues of horizon or of altitude instruments in the airplane, until the brain once again adjusts, and vestibular sensory input agrees with visual input.

See also

https://en.wikipedia.org/wiki/Graveyard_spiral

 

[IRstuff]

Still seems very odd, particularly these days. 25 years ago, a helicopter might have had to scab a GPS by sticky taping one to the dash, but that helicopter should have had at least the equivalent of a basic Garmin car nav system, which would have shown that they were veering 180 degrees away from their destination. They were following the 101 freeway, and the helicopter was ostensibly visible from the ground, so also vice-versa, and then the pilot turned away from their course in the last 20 seconds.

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[phamENG]

CFIT gives me the willies. I only have about 100 hours in Cessnas, and I'm glad most of it is on the coast. I've only headed up to the mountains a few times, and was paranoid in the extreme.

Flying in and around heavy clouds/fog is no fun, either. I couldn't imagine combining the two. My first solo was on a day with weather moving in (as it does nearly every day in the summer). My instructor and the chief pilot both agreed that there was enough room for me to get a couple turns around the pattern before I'd need to come in and still have a reasonable factor of safety. I was at 700ft MSL (which is only about 690ft AGL here) climbing out - first time alone in an airplane - when I hit a cloud. I had to break pattern at a "small" international airport and get back on the ground with conditions degrading a lot faster than anyone thought. My PIREP ended VFR that day. One of the scariest things that's ever happened to me.

As for the pilot's last minute turn...maybe he dropped is iPad and tried to reach for it...

 

[Alistair_Heaton]

You lot are trying to compare flying a fixed wing to flying a helicopter its a completely different ball game.

Pitch plus power = performance doesn't work the same way. And they have loads of gyroscopic tendency's to deal with.

Plus its extremely easy to get into attitudes where the gyros topple.

I don't know if a left turn like that is a common mistake, it may be linked to the direction of yaw when you apply torque to the main rotor. I think helicopters use bits of string on the windows to see yaw.

 

[IRstuff]

I get something like a 0.6 g turn; that seems a bit drastic for flying in limited visibility

He still had gobs of instruments telling him the same story, over the course of at least 40 seconds
> GPS moving map
> Attitude display system
> Instrument display system
> Horizontal situation indicator

TTFN (ta ta for now)
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[hpaircraft]

The solution, of course, is for the pilot to consciously override the brain's imperative to judge physical altitude on the basis of signals from the vestibular, and rely solely on the visual cues of horizon or of altitude instruments in the airplane, until the brain once again adjusts, and vestibular sensory input agrees with visual input.

I fly sailplanes and small airplanes, and for a dozen years I commuted two or four times a week on a six-seat airplane on which about 30% of our flights involved descending through cloud on IFR approaches. In my experience, it is difficult to explain to someone how hard it is to ignore sensations from the inner ear and rely instead on instruments. The sensations are very strong, and disregarding them, or at least compartmentalizing them as invalid, is a skill that takes experience to master, and which atrophies with disuse. In the absence of that skill, one is spring-loaded to trust their inner ear over the instruments.

 

[waross]

I am under the impression that normally the pilot will have his left hand on the collective and his right hand on the cyclic control.
When the pilot is changing channels on the radio, what is his hand position?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Alistair_Heaton]

They can trim the cyclic and also the collective.The left hand is on the collective.

The normal way is to take the hand off the collective for a couple of seconds. Alot of collectives they can change the frequency on a consol on the collective.

You can hear helo pilots getting a bit narked when ATC give them frequency changes while hovering.

He will have been pulling lots of collective to do the IMC escape climb.

This guy day in day out apart from check rides will be flying looking out the window.

here is the cockpit of the helicopter that crashed.

 

[itsmoked]

I just read an article where a decades-of-helicopter-flying chief pilot stated that flying a helicopter without visible clues up thru clouds results in disaster approximately 80% of the time if the pilot also makes the fatal error of attempting to turn while in the maneuver.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Eufalconimorph]

My theory has always been that helicopters fly by being so ugly the ground refuses to touch them. But with fog the ground can't see the helicopters, so they crash!

 

[Alistair_Heaton]

Eufalconimorph I completely agree with your analysis.

I won't go in one if I can help it.

 

[IRstuff]

Nevertheless, not only was there a turn, there was extremely steep descent rate; I keep being tempted to think it was an intentional CFIT.

TTFN (ta ta for now)
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[Alistair_Heaton]

IR stuff you need to go and have a play in a R22.

The contraptions fall out of the sky for the slightest excuse.