South Africa - Aircraft Stalls as Skydivers Prepare to Jump

[Tiger G]

Didn't see this one posted, apologies if it's a repeat:

https://www.youtube.com/watch?v=2XMESBk0dJw

Quote: "Incident info released for general information and educational purposes to the aviation community by videographer Bernard Janse van Rensburg, with the full knowledge of the drop zone operations.

The Beechcraft C90 King Air was trimmed up for the exit procedure at an altitude of 16000’ AGL for the second load of a planned 20x jump event. We opened the door and began the climb out. As is normal, the skydive team was fully focused on achieving correct positioning and exit timing. This intense focus on task resulted in many of the skydivers missing the tell-tale signs of an imminent stall.

From the videographer exit position (outside, most tail-ward end of the jumper line) I felt the plane 'slip' once and then twice after which I knew something was wrong and decided to let go of the now banking aircraft. This all happened inside of just a few seconds. Those on the outside of the door and immediately inside of the door followed. With 9 of us initially in the sky, there were still 5 skydivers inside of the aircraft.

The moment was surreal and I could not believe what I was seeing. Everything happened in slow-motion and I remember thinking 'am I really seeing the plane spinning nose down next to us'. After the spin, the aircraft started to veer underneath us but luckily did not make contact. As the aircraft started to recover from the stall (still unstable) one further skydiver exited, leaving 4 skydivers and the pilot in the aircraft.

After I was satisfied that the aircraft had recovered (it is a fascinating and unusual thing to see your jump aircraft below you in freefall), I searched the sky for my team and found them building the pre-planned formations in a safe and normal manner. The aircraft returned and landed safely on the runway. The incident was promptly reported to the South African CAA and PASA national safety and training officer. The next day the jump team made adjustments to their exit procedure following discussion with the pilot and no further incidents or near-incidents were experienced."

[Pilot DAR]

The next day the jump team made adjustments to their exit procedure following discussion with the pilot

Yeah! It's only fair to tell the pilot when what you're about to do to the plane he's flying will probably put it out of C of G limits, dramatically increase drag, obstruct some airflow over the tail, and cause a sudden unexpected weight change, all while he's flying as slowly as you have asked him to! I had four jumpers do this to me, while I was flying a C 185, resulting in my entering a spin. I remember being very fearful that I would hit them, as I rotated down, but I did not. I had swift words with them afterward, along with a talk with the boss! I extend (for now) the possibility that the pilot was a victim of an unexpected event, which a really good preflight discussion could have prevented. It is noteworthy that jump planes are often stripped down for weight saving. In the case of a King Air, what is stripped out (air conditioning and avionics) is usually in the nose, moving the C of G back already! If the pilot intended to allow that many people to cling outside the plane that far back, I hope he had some authority to permit flight so misloaded!

[DogTailRed2]

There is an interesting video on youtube of the same thing happening to a DC3.
Seems to happen quite frequently concidering the potential outcome.

[treadigraph]

I believe on one occasion Martin Caidin inadvertently spun his Ju-52 while parachutists swarmed out onto the wing (it survived to delight joyriders with Lufthansa for many years and I regret not managing to get a seat on flights out of London City before it became grounded...)

[DogTailRed2]

I believe on one occasion Martin Caidin inadvertently spun his Ju-52 while parachutists swarmed out onto the wing (it survived to delight joyriders with Lufthansa for many years and I regret not managing to get a seat on flights out of London City before it became grounded...)
That Ju52 used to fly over Kennington where I lived. Must have been 90's?

[biscuit74]

Wow - kudos to the pilot for there being a 'next day' drop !

A good two or two and a half turns of spin and some interesting wing rocks during recovery - perhaps because the pilot was pulling hard to try to stay within the flap limits as (presumably) the flaps motored up.

[tdracer]

Memory is foggy about the details, but there was a crash like this near Seattle back in the late 1980s - IIRC a couple of the jumpers still managed to get out after the aircraft went into a spin, but most were killed in the resultant crash.

[West Coast]

There is an interesting video on youtube of the same thing happening to a DC3.
Seems to happen quite frequently concidering the potential outcome.

https://www.youtube.com/watch?v=EFyyLbD-Y7o

The last few jumpers out got more than they bargained for.

[treadigraph]

some interesting wing rocks during recovery - perhaps because the pilot was pulling hard to try to stay within the flap limits as (presumably) the flaps motored up.

Flyer has a quote that, according to the pilot, the subsequent wing rocks were due to one engine spooling up more quickly than the other...

[tartare]

I wasn't even aware this was a thing - both of those videos are chilling to watch...

[Pilot DAR]

due to one engine spooling up more quickly than the other..

Yeah, who knows what the props were doing just before he stalled, presuming at a rather low power, and then maybe idle when he went over. PT-6's can spool up a little differently if you rush the power levers and things were not stable to begin with.

As for the DC-3, they have stall characteristics which must be understood, and trained, as the design precedes today's standards for handling. I have errantly done exactly what that video shows, during stall testing of a modified turbine DC-3, yes, it's a thing. Again, everyone crowded at the back of the cabin is terribly destabilizing, and a DC-3 is particularly vulnerable to this!

[biscuit74]

Thanks treadigraph and Pilot DAR. That makes sense. An exciting time. It looks as if the aircraft try to spin again, to the right, on first recovery.

[Vessbot]

Flyer has a quote that, according to the pilot, the subsequent wing rocks were due to one engine spooling up more quickly than the other...
I would put more money on the elevator being held firmly against the aft stop causing the 3 or 4 secondary stalls and incipient spins

[Pilot DAR]

The added challenge of spins in more "sleek" airplanes is that they build up speed very quickly on the way down. The vertical attitude, combined with the buildup of speed causes pilots to want to recover too early, though too late will assure an exceedance. I did a spin program on a modified Cessna Grand Caravan, and without the G meter I installed for the testing, I would have certainly exceeded Vne during the post recovery dive. A "normal" spin recovery in the Grand Caravan at forward C of G and near gross weight was 2.5G pull, and just about Vne, meaning that not pulling the 2.5 would have assured exceeding Vne. The aft C of G spins were an entirely different thing!

[fitliker]

The King Air had almost full aileron by the time the jumpers got ready to leave . Hence the left wing stalling more than the right inducing the roll over spin entry . Usually close to a stall in a King air you get a lot of buffeting and loss of lift before any change in attitude . Interesting to watch the rolling moment as the left wing is more stalled by the aileron than the right wing .

Airspeed is life

[megan]

Loss of control on the jump run is some thing that should be foremost in the pilots mind. It's not a unknown event, pilot might like to think how he is going to get out as well if all turns to worms, it's why these days he has to wear a parachute, not the case in my day.

https://www.youtube.com/watch?v=N__ewzWENyA
https://www.youtube.com/watch?v=4pVUIiYAQhU
https://www.youtube.com/watch?v=VJdIU0zKxE4

Skydiving accident.

https://www.atsb.gov.au/publications/investigation_reports/2001/AAIR/pdf/aair200101903_001.pdf

Video of the above accident taking place, note the height when the pilot gets out.

https://www.youtube.com/watch?v=TCyt-sIMym0

[rnzoli]

Not unusual, but always frightening
9IQR-OOsbZg

[Pilot DAR]

it's why these days he has to wear a parachute,

Yes, this became a requirement in Canada just as I started flying jumpers. A pilot lost control and spun a Cessna 180 jump plane locally, lost control, and they were all thrown from the plane. The pilot was not wearing a 'chute, though the jumpers were all fine. I had zero intention of ever using the 'chute they provided for me (and never did), but I guess it was reassuring (as was my extra check of my seatbelts!). Though I don't know much about types of parachutes, I suspect that the large pack they provided to me was really not intended for pilot use, as it fit terribly with the seat, and was entirely uncomfortable!

[fitliker]

It would be very difficult to egress a plane with no pilot door or hatch . Getting out while being thrown about might take a lot of altitude and having a plan of what if’s . How to use your legs in a g load situation as your arms might not have enough strength to pull you out .

The first king air video shows a tenth person exiting northbound as the plane is recovering heading east .

EFS

[ehwatezedoing]

I would put more money on the elevator being held firmly against the aft stop causing the 3 or 4 secondary stalls and incipient spins
The pilot specifically said that the subsequent wing rocks were due to one engine spooling up more quickly than the other and you come up with this theory on your own!?
Pure pilot bashing....

I went very, very close to stall a Beech 18 one time during a jump run and for the exact same reason, way too many far back.
It's a strange feeling when you push your elevator all the way forward to its stop and the aircraft is doing the exact opposite.

[Rich Kovaly]

Yeah! It's only fair to tell the pilot when what you're about to do to the plane he's flying will probably put it out of C of G limits, dramatically increase drag, obstruct some airflow over the tail, and cause a sudden unexpected weight change, all while he's flying as slowly as you have asked him to! I had four jumpers do this to me, while I was flying a C 185, resulting in my entering a spin. I remember being very fearful that I would hit them, as I rotated down, but I did not. I had swift words with them afterward, along with a talk with the boss! I extend (for now) the possibility that the pilot was a victim of an unexpected event, which a really good preflight discussion could have prevented. It is noteworthy that jump planes are often stripped down for weight saving. In the case of a King Air, what is stripped out (air conditioning and avionics) is usually in the nose, moving the C of G back already! If the pilot intended to allow that many people to cling outside the plane that far back, I hope he had some authority to permit flight so misloaded!
I have a question. I am not a pilot and I kind of predicted as to what could have caused the plane to do what it did, but since I am not a pilot, or a mechanic, could you explain to me why the engines stalled? I can guess that the extreme drag could have through the whole thing out of whack, but I wouldn't have thought that the engines would shut down from it. Your going to laugh at me, but I can understand it in my head, I just can't put words to paper to explain it. lol. Could you please explain it to me so my conscious mind can understand it. :)

[Vessbot]

The pilot specifically said that the subsequent wing rocks were due to one engine spooling up more quickly than the other and you come up with this theory on your own!?
Pure pilot bashing....

I went very, very close to stall a Beech 18 one time during a jump run and for the exact same reason, way too many far back.
It's a strange feeling when you push your elevator all the way forward to its stop and the aircraft is doing the exact opposite.

Certainly a severe aft weight load can explain running out of forward elevator authority as in your anecdote... while that weight is still onboard. But not after that weight jumps out.

And while it's certainly possible that a faster spooling engine on one side can induce a yaw and in turn a roll (and a spin given high AOA) it's hard to imagine (putting it lightly) one side spooling up faster, then the other side, then the first one again, then the other again, a 4-time reversal.

The pilot may have told his story, but I would not take it as the definitive recounting of the events, given 1) the high misunderstanding of flight dynamics that many pilots have, and 2) the potentially warped perception of a stressed and overwhelmed experience like this. This isn't an attempt to trash talk this particular pilot, it's just human nature. And if the pilot didn't realize what he was doing during the maneuver, his recollection after is very likely to be similarly flawed.

To more reliably build a picture of the events, we have to take in the video and circumstantial evidence. And the circumstance of someone who doesn't regularly practice spins, is that it's very common for muscle memory (aft elevator to move the nose up and out of the ground) to overwhelm any reasoned notion of the proper thing to do with the elevator. Including after a recovery. Add on the tunnel visioned stress of suddenly finding yourself in a spin in a large multiengine airplane not certified for this maneuver, I think the likelihood of an improper response only increases.

And what we see in the video after the first recovery and a sudden normal acceleration (to the right in the frame) consistent with high AOA. And after that, a series of roll reversals (some with yaw) immediately one after the other, with sudden pitchups in between... again consistent with high AOA, with the pilot doing their best to control the thing with rudder. Just like the "falling leaf" exercise in basic trainers where the plane is held in a stall.

I think Pilot DAR above may be on to something with the pilot overdoing an attempt to level off before the slick airplane accelerates past its airspeed limit (especially the flap speed limit), but in that case why would the power be advanced at all?

[sfm818]

Jump pilots/sports parachutists reading this will be aware of Skies Call by Andy Keech - he captured the ultimate selfie of skydivers clambering all over a Lockheed 10E (Zephyr Hills?) Yes, it was a thing back in the Para- Commander days.

[Maoraigh1]

"could you explain to me why the engines stalled?
Engines throttled back as part of spin recovery? They didn't stall.

[Locked door]

Hi Rich,

Stalling an aeroplane has nothing to do with the engines, you can stall an aeroplane with all engines at full power.

The word stall is used to describe the situation when the angle of attack of the air passing over the wings exceeds the maximum causing the airflow to break away from the wings and causing a sudden loss of lift. For many reasons this can then lead to a spin.

You can stall an aircraft at high speed, low speed, pointing straight up or straight down, full power or in a glider.

HTH

LD



I have a question. I am not a pilot and I kind of predicted as to what could have caused the plane to do what it did, but since I am not a pilot, or a mechanic, could you explain to me why the engines stalled? I can guess that the extreme drag could have through the whole thing out of whack, but I wouldn't have thought that the engines would shut down from it. Your going to laugh at me, but I can understand it in my head, I just can't put words to paper to explain it. lol. Could you please explain it to me so my conscious mind can understand it. :)

[Teddy Robinson]

Sorry to play devils advocate here, but please look at some of the control positions and inputs when the aircraft should be RECOVERING from the spin.

In another, there are full pro-spin controls held during a supposed recovery, (reminds me of someone that tried to kill me in a Pa38)

I counted pro spin rudder, into spin aileron, and aft elevator in at least two of the videos ... do they not teach this stuff anymore ?

Sure, the aircraft is operating on the edge of the envelope, but if you are going to do that at least know how to recover if things go wrong.

[Vessbot]

Sorry to play devils advocate here, but please look at some of the control positions and inputs when the aircraft should be RECOVERING from the spin.

I counted pro spin rudder, into spin aileron in at least two of the videos ... do they not teach this stuff anymore ?

I see right (anti-spin) rudder at all points where I can see the rudder in the first spin, as the subsequent ones it gets too small to see. I also can't see the ailerons at any point after the original entry.

edit: I see I think you were talking about the other videos, not the original one

[vegassun]

Jump pilots/sports parachutists reading this will be aware of Skies Call by Andy Keech - he captured the ultimate selfie of skydivers clambering all over a Lockheed 10E (Zephyr Hills?) Yes, it was a thing back in the Para- Commander days.

Was that the infamous "Twin Spin?" I thought that was out in Cali somewhere, but that was a long time ago.

[megan]

Skies Call by Andy KeechKnew Andy before he went to the US, last saw in Washington when he working in the Australian Embassy '67. Made a name for himself as a photographer in the jump scene.


https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/400x252/keech_29a5bf1d191f2916722a409e50c9755beb3aedbe.jpg

North Carolina some where he says in an article, not Zephyr Hills.

[Teddy Robinson]

I see right (anti-spin) rudder at all points where I can see the rudder in the first spin, as the subsequent ones it gets too small to see. I also can't see the ailerons at any point after the original entry.

Then look again, and watch the control inputs in the SE turboprop.
I am so disturbed with some of the videos I am not going through them again, but there are pro spin controls, aft elevator, and guys messing with the ailerons, all kinds of yeehaa stuff going on in some of them.

"Identify direction of spin, close throttle(s), full opposite rudder, ease the stick forward until the rotation stops, centralise rudder, recover from dive apply power as the nose reaches the horizon"

Mess with the ailerons, you are test flying unless it's a Pitts or similar.

[pchapman]

Of course every dropzone & skydiving aircraft operator have their own procedures for handling jump run without stalling. What jump run speeds, what engine & flap settings, how many jumpers outside the door at one time, sometimes how many jumpers allowed aft of a red line on the floor at once, all those sorts of things.

But sometimes people and dropzones are still learning, procedures and skills are not perfect, and so on.

In the King Air event that started this thread, I notice that they were jumping from 16000' AGL according to the description. (At a DZ by the sea, so it should be about 16k' ASL too) That's an unusually high altitude, when typical turbine jump operations are from 12k to 14k at the most. I'm guessing the extra altitude was unusual, so right at the start of a special event going to that altitude, what worked down lower didn't quite work out any more. Little way of finding out without actually doing it.

So no kidding they adjusted procedures for the next load!

While I'm not necessarily that critical of the pilot for stalling it, I was less impressed with that long recovery process. Admittedly pilots don't exactly practice spinning King Airs a lot but there are procedures for inadvertent stalls or spins.

(I have 4k jumps. I was a jumper inside a Caravan during a jump run stall, but that was relatively mild, with the pilot not exceeding 60 degrees of bank on recovery.)

[SaulGoodman]

Of course every dropzone & skydiving aircraft operator have their own procedures for handling jump run without stalling. What jump run speeds, what engine & flap settings, how many jumpers outside the door at one time, sometimes how many jumpers allowed aft of a red line on the floor at once, all those sorts of things.

But sometimes people and dropzones are still learning, procedures and skills are not perfect, and so on.

In the King Air event that started this thread, I notice that they were jumping from 16000' AGL according to the description. (At a DZ by the sea, so it should be about 16k' ASL too) That's an unusually high altitude, when typical turbine jump operations are from 12k to 14k at the most. I'm guessing the extra altitude was unusual, so right at the start of a special event going to that altitude, what worked down lower didn't quite work out any more. Little way of finding out without actually doing it.

So no kidding they adjusted procedures for the next load!

While I'm not necessarily that critical of the pilot for stalling it, I was less impressed with that long recovery process. Admittedly pilots don't exactly practice spinning King Airs a lot but there are procedures for inadvertent stalls or spins.

(I have 4k jumps. I was a jumper inside a Caravan during a jump run stall, but that was relatively mild, with the pilot not exceeding 60 degrees of bank on recovery.)

16 or 13K doesn’t really matter.

when I watched this clip for the first time I thought as well the recovery took quite some time. Having seen it a few times more and actually thought about it I think he did a good job. Spin recovery is easy when you expect it. I have at least 500 jump runs and never stalled. If it happened to me I hope I recover immediately but there is also the “startle and surprise” effect.

[JRK]

https://www.youtube.com/watch?v=EFyyLbD-Y7o

The last few jumpers out got more than they bargained for.

Looks like the pilot decided to join the skydiving party :)

Either way, some impressive footage there...

[JRK]

Sorry to play devils advocate here, but please look at some of the control positions and inputs when the aircraft should be RECOVERING from the spin.

In another, there are full pro-spin controls held during a supposed recovery, (reminds me of someone that tried to kill me in a Pa38)

I counted pro spin rudder, into spin aileron, and aft elevator in at least two of the videos ... do they not teach this stuff anymore ?

Sure, the aircraft is operating on the edge of the envelope, but if you are going to do that at least know how to recover if things go wrong.


Well, he recovered didn't he? So, I guess must have done it right, all things considered...

Or is your issue more with the time it took for him to get it flying again?

[Pilot DAR]

Well, he recovered didn't he? So, I guess must have done it right, all things considered..

Yes, as long as it was not over stressed or oversped during the recovery. Or. if it was, the pilot reported it. The 185 I used to fly jumpers in, was spun from jump run after I left that flying. The pilot landed, so I guess it worked, but they later found the the wings were wrinkled badly enough to write the plane off. A friend of mine bought it to rewing it. "Right", includes assuring that the next pilot, or maintenance person, is aware of any possible exceedances or defects resulting from what you did in it...

[oggers]

I did a spin program on a modified Cessna Grand Caravan, and without the G meter I installed for the testing, I would have certainly exceeded Vne during the post recovery dive. A "normal" spin recovery in the Grand Caravan at forward C of G and near gross weight was 2.5G pull, and just about Vne, meaning that not pulling the 2.5 would have assured exceeding Vne. The aft C of G spins were an entirely different thing!

The Caravan is a turbine and is certified with a Vmo. It does not have a Vne. Although both speeds provide a margin to Vd they should not be confused because the Vne is literally the never exceed speed whereas Vmo/Mmo is a nominal limit approved to account for the inevitability of some speed excursions whilst operating there.

[henra]

Well, he recovered didn't he? So, I guess must have done it right, all things considered...
Or is your issue more with the time it took for him to get it flying again?
Looking at the way the control surfaces were deflected during first recovery attempts and knowing that twins are not spin tested/certified, I do understand unease when looking at this video. Two more turns due to ailerons still in spin inducing position and elevator solidly NU, I'm not sure he would still have been able to get it out of the spin. This might have been a very close call.

[Pilot DAR]

The Caravan is a turbine and is certified with a Vmo. It does not have a Vne.

Yes, I stand corrected, it is presented as Vmo, rather than Vne for the Caravan. Though for either limiting speed, there is no authorization to exceed the speed within the certified limitations. For the flight testing I have done in Caravans the Vd agreed by the authority for the testing was 1.1 of Vmo, though there were discussions for a couple of projects that Vd might be a greater value than that. I've never flown the Caravan faster than 193 KIAS during testing. More simply, I'm saying that for the Caravan, and similarly sleek airplanes, it can be surprisingly easy to get to that limiting speed if you point the airplane down too much/too long! The Caravan is very forgiving in unusual attitude recovery, though a G meter is a good idea if you're going to do silly attitudes!

For all certified planes, the G (flight load factor limits) are presented as limitations, and the pilot of any airplane not equipped with a G meter has no way of knowing when the G limit is being approached.

[pchapman]

16 or 13K doesn’t really matter.

You got a better idea? Ok, it is a turbine aircraft with good altitude performance, so maybe that's only a small difference in altitude, fair enough.
The pilot report stated, "The stall and subsequent spin happened when we allowed too many jumpers on the outside step, " ... but that doesn't say whether it was "more than usual" or just "too much for the given conditions".
Because it was a special event, maybe the number of people for that group was larger than usual or more focused than usual in keeping tightly packed near the doorway -- while at the same time perhaps the DZ's rules on the number of floaters wasn't that well established or perhaps communicated.

But it doesn't matter in the end too much here to us out on the internet. The drop zone would know "what factor changed", why a normal everyday jump run procedure didn't work this particular time.

[punkalouver]

Yes, as long as it was not over stressed or oversped during the recovery. Or. if it was, the pilot reported it. The 185 I used to fly jumpers in, was spun from jump run after I left that flying. The pilot landed, so I guess it worked, but they later found the the wings were wrinkled badly enough to write the plane off. A friend of mine bought it to rewing it. "Right", includes assuring that the next pilot, or maintenance person, is aware of any possible exceedances or defects resulting from what you did in it...

Interesting. The 180 I used to fly had a VFR only guy get into a cumulus cloud on a fairly nice day resulting in a spiral dive and sharp enough pull-up to structurally damage it significantly. It seemed to look fine and I actually ended up jumping out of it that same day after it started flying again. The usual dropzone kind of stuff that seems to happen. And a good reminder that significant damage can be well hidden.

[visibility3miles]

Overweight, center of gravity problems, skydivers/passengers that don’t understand weight and balance…

https://diverdriver.com/accidents/beech-c-45-fatal-14-taft-ca-october-17-1982/Beech C-45 Fatal (14) Taft, CA October 17, 1982The aircraft was on a local flight involving a parachute jumping activity. In addition to the pilot, there were 12 parachutists and an observer on board. The pilot initiated his takeoff on runway 18. A witness stated that shortly after takeoff, the engine power was reduced to climb power, followed by the gear retraction. Reportedly, the aircraft had climbed to about 150 ft agl when the nose pitched up, th plane rolled to the left and then it crashed in a steep left bank, nose down attitude. An investigation revealed that the aircraft was loaded well beyond its maximum gross weight and aft cg limits. The amount of fuel on board was not verified, but even with no fuel, the plane would have been about 580 lbs over the maximum limit. With 100 gallons, the estimated gross weight would have been about 9939 lbs with the cg at about 121 inches. The maximum certificated gross weight was 8750 lbs with an aft cg limit of 117.6 inches. Extensive ground fire damage, but no preimpact, mechanical discrepancies evident.

[visibility3miles]

You got a better idea? Ok, it is a turbine aircraft with good altitude performance, so maybe that's only a small difference in altitude, fair enough.
The pilot report stated, "The stall and subsequent spin happened when we allowed too many jumpers on the outside step, " ... but that doesn't say whether it was "more than usual" or just "too much for the given conditions".
Because it was a special event, maybe the number of people for that group was larger than usual or more focused than usual in keeping tightly packed near the doorway -- while at the same time perhaps the DZ's rules on the number of floaters wasn't that well established or perhaps communicated.

But it doesn't matter in the end too much here to us out on the internet. The drop zone would know "what factor changed", why a normal everyday jump run procedure didn't work this particular time.

”16 or 13K doesn’t really matter.”

Aren’t you required to use oxygen above a certain altitude? At least for the pilot.

Inadequate oxygen can lead to stupid decisions by both the pilot and the passengers/skydivers, especially as the higher you fly, the longer it takes to get to altitude, so the more time you spend with inadequate oxygen, especially if you are used to the amount of oxygen available at sea level and your body is not acclimated to low oxygen conditions.

And obviously a plane is far more likely to lose lift and stall the higher you fly, as the air thins and lift is reduced.

[Warren Peace]

The basic premise of this **** is that somehow it’s ok to get out of the aircraft, and not part company with it.

I am reminded of many video clips where the hard of thinking are seen crashing a motorcycle they have been trying to wheely at high speed for a long distance.

jumping out of the door, in a pre planned sequence is just about safe. Clambering out onto the airframe is crazy, allowing it is worse.

[RationalKeith]

....supect that the large pack they provided to me was really not intended for pilot use, as it fit terribly with the seat, and was entirely uncomfortable!

You might check for the compact parachute once used by USNavy pilots. Ripstop nylon for strength at high deployment speed.

Perhaps a modification to seat padding, on a spare set of cushions.

[RationalKeith]

Pilot should use oxygen that high, jumpers will just get dozy.
Oh! wait, they have to be on the ball to pull deployment cords and maneuver. :-o)

Every person should test their blood oxygen at altitude to see if there lungs are functioning well, before spending time at altitude while needing to be alert. Small airplane pilots have been surprised at deterioration of their body with aging/health problems. (Cheap ones readily available, Nonin is the class one but can be hard to find as distributors are bureaucracies, AeroMedix sells a clip-on-finger one, Nonin also makes a recording one with low-profile sensor and wrist recorder.

(Accident over eastern BC, airplane had temporary oxygen system while regular one was being fixed, experienced pilot had to take mask off temporarily to use radio, probably forgot to put it back on, IIRC was flying at 15,000 feet ASL to clear huge rocks sticking up.)

Do airliner pilots test regularly? Should be done by doctor on periodic review.

[RationalKeith]

Does anyone have a link to the South African report on the case in question? (You linked to an Australian report on different case.)

[megan]

Does anyone have a link to the South African report on the case in questionNo record of a report on the Authorities site, here is what Russ Niles of Avweb says the pilot had to say.The pilot of a King Air C90 that went into a spin while skydivers prepared to jump over South Africa on Oct. 14 says the plane departed controlled flight because too many jumpers got out of the rear exit at the same time. The dramatic video of the incident has gone viral and been featured on network news shows but it was all in a day’s work for the pilot, who identified himself as Xei. “The stall and subsequent spin happened when we allowed too many jumpers on the outside step, causing an aft center of gravity and excessive blocking of the airflow to the left horizontal stabilizer. The nose then pitched up beyond the controllability of the elevator,” he said in a post that accompanied the video on YouTube.He said he quickly ran out of rudder and elevator and after the right wing came over he chopped power to both engines and began the recovery. “The aircraft behaved very well, and the recovery was surprisingly easy,” Xei wrote. “I pulled out as gently as possible as I did not want to stress the airframe. There was some additional instability when I pulled out of the dive and pushed the throttles forward to power up, as the one engine spooled up much quicker than the other and caused another asymmetrical moment.”

He also said the aircraft is intentionally flown with asymmetrical power for the release of jumpers to prevent them from being blasted by the propwash from the left engine. “Power is kept on the right engine to maintain altitude during the jump run, which typically takes 60 seconds,” he wrote. “A fair amount of right rudder is required to fly a straight line in this configuration. Pilot to maintain 95-90 kts IAS.” He said the incident was reported to authorities and the aircraft inspected. He said the operation has now limited the number of jumpers outside to five at a time and skydivers will be briefed to let go if the aircraft suddenly pitches up.Avwebs Paul Bertorelli, an experienced skydiver,Last week, my various inboxes filled up with links to the video posted here, attached to the question, “have you seen this?” How could I not? Shortly after it was posted, it rocketed around the skydiving village like a rubber check in a tile bathroom. I spent a couple of days last week doing intensive wind-tunnel training and we discussed it during our breaks. Suffice to say it’s one of a kind only to the extent that the stall/spin was dramatically captured by a videographer. It is hardly a first and as much as I might wish that publishing it here will make it the last, I know that this passing thought gives futility a bad name. My reaction to these things is often, “the things we get away with in this sport that don’t kill us.” It might deserve firsties for pinning five skydivers inside the airplane during the spin, however.

There’s a lot wrong here related to decision making, judgment and execution of what planning may have been in place. That means there’s a takeaway related not just to skydiving flight operations, but flying in general. It relates to just saying no sometimes. As described in the video summary, this was a workup jump to a 20-way event at a South African drop zone. Presumably those would have been with two-aircraft formations since a King Air won’t carry but about 14.

To my eye, the first thing that went wrong is that they took off in the first place. The exit was above a broken to overcast layer and although it was thin, the videographer’s footage shows it was right at the altitude where the skydivers broke off to gain some separation for canopy deployment. In freefall, I don’t like being in clouds, being near clouds, or going through them, period, much less with a large group. Deploying with zero visibility invites a canopy collision, especially if the break-off tracking happens in cloud with no visual reference.

When this jump unraveled, the organizer did the standard pull-it-out-the-bag salvage by signaling for a round formation. He may or may not have known five jumpers never got out of the airplane due to the stall/spin. Carrying on with some semblance of the dive made sense because that was the plan and keeping a group together for an orderly break-off is preferable to everyone careening around the sky looking for separation to deploy.

Jumping in other than perfectly clear conditions requires judgment on the part of the drop zone operator, the pilots and the skydivers themselves. In my experience, the latter have the least ability to make a wise call because doing so means, at best, you may have to go around for another pass or just land with the airplane, usually losing the cost of the jump ticket. Horrors. So skydivers want to exit no matter what and many will. Sometimes, the pilot—who is on the enforcement hook for jumpers busting clouds—just has to say no to taking off in the first place.

This video reminds me of why I don’t like jumping King Airs. They are not a common jump ship, but because they’re relatively cheap, some drop zones use them in lieu of Twin Otters or Caravans. For aircraft, skydiving is a utility operation and Otters and Caravans, with big doors, fixed gear and hell-for-strong structure, are utility airplanes. King Airs are really business airplanes, with smaller doors and retractable landing gear which increases operational and maintenance complexity. One weakness of King Airs is a relatively narrow, aft-tending CG that means the airplane isn’t tolerant of six or seven people hanging off the bars and maybe a videographer perched out near the tail close to a CG station Beechcraft never figured was relevant.

Skydivers know bupkis about center of gravity. They just assume if they can crawl out there and hang on until exit, the airplane will shrug it off. So the smarter dropzones and organizers who have been through stalls, brief the jumpers on how to do these exits. For every jump, we dirt dive the plan on the ground and set up and practice the exit in a ground aircraft mock-up. Sometimes several times. This is the point where the skydivers in the front of the airplane need to be reminded to stay there until that instant when the outside people are just departing and they can rush the door without causing a stall. In an Otter, you can put six outside and three close in to the door inside and the rest spaced out in the airplane and some forward. It is true that the forward-most skydivers will be delayed diving down to the formation by a few seconds, but better that than being slammed into the cabin walls during a spin entry.

I have been through two stalls in Otters, albeit no spins. I was standing outside for one and departing from the inside for the other. I knew what was happening, even if my fellow skydivers did not. I’ve seen this from both sides. (Sounds like a song.) I’m hardly a Twin Otter expert but I’ve flown enough Otter loads to understand what happens and it’s challenging to deal with it. The usual drill is to reduce power on the left engine and trim up for 90 to 95 knots indicated. When a big group gets out of the door—say eight or 10 perched for exit—the pitch moment starts heading north and it will continue to do that until they exit. If they’re slow about it, you know what’s coming when there’s no more elevator authority left. In this case, the pilot told authorities he reduced the left engine to idle and the prop to coarse pitch, otherwise the jumpers would have too much prop blast to set up the exit.

There’s not necessarily universal agreement on how to fly these jump runs. Some pilots don’t do asymmetric thrust in any twins, some do. For the King Air, www.diverdriver.com (https://diverdriver.com/king-air-90/) recommends flaps and flight idle for the exit, but some power on the right side if the pilot wants to minimize altitude loss. Extreme asymmetrical power seems to be asking for trouble, especially if power isn’t available quickly on the left side if needed.

So skydivers have to be briefed about all this. Hang out there long enough and you’ll cause a stall. Or put too many out there and you’ll cause a stall. And that’s what happened here, along with a rolling moment and enough yaw to initiate a spin. The recovery was quick; it’s only about a turn and a half. I can’t tell for certain, but once the spin stops, there may be some secondary stalling going on during the recovery. King Airs build speed rapidly and the pilot said he wanted to avoid that and may have commanded pitch up too aggressively during the pull out. The pilot attributed the unstable rolling to one engine spooling up faster than the other, but I’m not so sure about that.

The jump organizer can and should have avoided this. The DZO and pilot should have made sure he knew not to put so many people outside and not to keep whoever was out there in place for so long. These guys didn’t discover this on their own. This has happened before and King Air operators know about it. Still, when skydivers get all amped up with adrenaline before an exit, they sometimes ignore the briefing. More than a handful of times, I’ve grabbed jumpers by the collar to haul them back from the door until a bigger group exits.

The most egregious example of this I ever saw was during the 400-way record skydives in Thailand in 2006. We had 410 people in five C-130s. The plan had been for two passes with 200-ish formations on each one, as practice set-ups. These were from 24,000 feet. So it was suggested when the first group exited, the second would walk to the back of the airplanes, pick up the oxygen tubes from the departed jumpers and await the second pass. No, don’t even, said one of the organizers with experience in high-altitude exits. Stay on your butt and stay on oxygen until exit time and then go.

But we did exactly the opposite of that and it was a near catastrophe. One of the jumpers picked up a disconnected oxygen line and became hypoxic enough to fall flat on his back right in front of me. Wisely, the ramps were closed up and we rode the airplanes down—all 200 of us—proving once again that something as risky as skydiving requires unrelenting discipline. The challenge of it is often just learning to think straight with a quart of adrenaline gushing through your veins.

As is obvious here, sometimes you can’t.
https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/600x426/hocmo3a92gs6o3ydfo90mxrv5fcqwqrte_wm8wcyq5u_c6e31996936b2605 e8f1dc5bd67803c47b3da4a5.jpghttps://cimg9.ibsrv.net/gimg/pprune.org-vbulletin/512x348/c_91469b37175ad7283483b1d06dee8a0963b9d5b4.png

[DaveReidUK]

Orinally Posted by RationalKeith
Does anyone have a link to the South African report on the case in question? (You linked to an Australian report on different case.).

The OP simply stated that the event was reported to the SA CAA. I'd be surprised if that resulted in an investigation.

[Mogwi]

And obviously a plane is far more likely to lose lift and stall the higher you fly, as the air thins and lift is reduced.

Nope. Lift is proportional to the square of the air speed and will occur at the same IAS no matter what the density of the local atmosphere. It is the TAS that will change with height - and not many aircraft I know fly on TAS.

It is lack of thrust that is the snag at high level.

Mog

[LOMCEVAK]

And obviously a plane is far more likely to lose lift and stall the higher you fly, as the air thins and lift is reduced.

Nope. Lift is proportional to the square of the air speed and will occur at the same IAS no matter what the density of the local atmosphere. It is the TAS that will change with height - and not many aircraft I know fly on TAS.

It is lack of thrust that is the snag at high level.

Mog

Mog,

Not quite. Dynamic pressure is a function of EAS not IAS and as altitude increases the IAS for a given EAS will increase slightly. Therefore, the IAS for stall speed will increase slightly as altitude increases.

[megan]

LOMCEVAK, I don't think we need to be that fussy, 90 CAS at 16,000 ISA is 89.827 EAS, 115.109 TAS. I don't think .173 ktots is some thing to to get the knickers in a twist.

[LOMCEVAK]

megan,

Hence why I said ‘not quite’. I think that Mog knows me well enough to realise that I was not criticising him but adding a little so that if anyone on here was interested they would have an accurate understanding that would be applicable to other conditions where the difference may be significant.

[megan]

Gotcha :ok: Can be significant as you say, SR-71 ISA 75,000 3.2M 842CAS 393EAS 1,847TAS

[LOMCEVAK]

And then there is the variation in the maximum coefficient of lift for a given wing as a function of Mach number and Reynolds number but let’s not dig the rabbit holes too deep in this thread.

[Pilot DAR]

To keep the topic relevant, should I delete the preceding six posts? Jump runs from SR-71's are a stretch!

From my Piper Cheyenne days, I recall that the plane seems more twitchy to fly higher than the high 'teens, but I don't have a lot of experience up there. I accept that the King Air pilot was pushing the bounds by approaching a messy stall at 16,000 feet, and my limited experience has me thinking that maybe the less dense air resulted in delayed recovery.

[Bergerie1]

megan,

Can you tell me more about those two photos you posted - the circumstances, the dates, who did it, etc. A friend of mine who used to drop skydivers from a DH Dragon Rapide and an Antonov An-2 is interested.

[megan]

From the web Bergerie, came across them when looking for a similar photo taken by Andy Keech, no details re what, when, where.To keep the topic relevant, should I delete the preceding six posts? Jump runs from SR-71's are a stretchYout train set DAR, post #49 should remain as Mogwi was correcting an incorrect statement, jumps have been made from the -71, but out of necessity. :p

[Pilot DAR]

jumps have been made from the -71, but out of necessity.

I'm sure they have! But, were they may during a jump run? Okay, I'll bite... Could you even jump from a fast Jet? Or, would you have to eject to get out?

[megan]

What constitutes a fast jet DAR? 727, DC-9 fast enough? :p

https://www.youtube.com/watch?v=2E-sakwt7ow
https://www.youtube.com/watch?v=Y3TtL2cmlcM

[blind pew]

One of the members of the dublin gliding club recounted a story about removing the canopy on his Blanic and taking a parachutist up. The parachutist gave his camera to the pilot then climbed onto the wing but decided that the Kodac moment would be more spectacular sitting on the wingtip. He didn’t quite get to the end as on the verge of loosing control of the glider the pilot lobed the camera at him and the parachutist followed in an attempt to retrieve the camera.

[DaveReidUK]

I love the way the video intro on You Tube credits D B Cooper with the inspiration. :O

[megan]

Jumpers don't need any inspiration Dave, they'll jump from absolutely anything that can gain altitude, some even mountains, cranes, buildings, bridges, etc etc

[rnzoli]

One of the members of the dublin gliding club recounted a story about removing the canopy on his Blanic and taking a parachutist up. The parachutist gave his camera to the pilot then climbed onto the wing but decided that the Kodac moment would be more spectacular sitting on the wingtip. He didn’t quite get to the end as on the verge of loosing control of the glider the pilot lobed the camera at him and the parachutist followed in an attempt to retrieve the camera.
All stories get more colorful with every telling :) No need to harm a camera, just allow a 90-degree bank and problem is solved. Nonetheless, the skydiver is considered insane on the credits page.
There is an actual video of this, and yes, significant aileron input is necessary to compensate for the rolling moment, but it's OK, if there is enough speed.
2uMZ9w7tbgc

[blind pew]

Ah you didn't know this Irish man.
I first met him when we derigging a K13 on Inch Strand with a darkening sky, sideways rain and the beach disappearing with the incoming tide. He had his arms crossed and let us struggle short handed.
The obvious way to me was to roll inverted but ...
Iirc he became a part of an alternative club..Irish politics..

[Big Pistons Forever]

Meat bombs have to be saved from themselves.

Let’s see the situation

1) 16k feet and nobody on O2

2) 15 pax in an airplane designed for 8 with all of them crowded in the back

3) Deliberately created significantly asymmetric thrust while entering slow flight

4) A whole bunch of guys hanging on to the outside of the airplane

What could possibly go wrong :rolleyes:

If you are a jumper dumper your challenge is when, not if, the jumpers try to kill you, you had better have your “A” game flight skills ready.

You also have to be able to say “NO” , “what part of “NO” didn’t you understand”, and “Are you Freakin CRAZY, there is NO WAY I am going to do that”

[Pilot DAR]

You also have to be able to say “NO” , “what part of “NO” didn’t you understand”, and “Are you Freakin CRAZY, there is NO WAY I am going to do that”

"Cause after all, you are the pilot in command! You state how the airplane is to be loaded, and what the passengers may and may not do in flight. If passengers are doing something which results in exceeding operating limitations for the plane, it's up to you to have them stop. This very certainly includes load (size/number/weight), and loading from a C of G perspective. I flew jumpers for two seasons, but when I could no longer reach agreement as to my flying within the limitations of the plane, I no longer offered to fly. I was replaced with a fresh 300 CPL, who would do things their way. I found that jumpers, nice a people as they are, were much more interested in getting out at altitude, than anything to do which how they get there.

In my opinion, being a jumper pilot should require receiving prior decision making training.