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Nine killed in plane crash in northern Sweden

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Nine killed in plane crash in northern Sweden

Old 26th Jul 2019, 23:15
  #21 (permalink)  
 
Join Date: Jan 2009
Location: Sweden
Age: 52
Posts: 151
Originally Posted by Steepclimb View Post
Loss of control after inadvertent or otherwise entry into IMC with a subsequent overstress on attempted recovery. It's so easy to find yourself in a spiral dive after being distracted by the jumpers. Don't ask me how I know.

(Ice)
A stall, spin on the run in is possible but most likely a few people would have got out in that case. Besides the Airvan has a docile stall even with everyone crowding the exit.

​​​​​
There is some quite story-telling data available from webtrak, where you can find the SSR track data from this flight.
WX is not 100% sure about cloud layers but FEW at around 5K feet, BKN at around 8K feet and OVC at 10K. A METAR close after says Towering Cumulus.
From the accident videos a solid layer can be seen.

The webtrak data converted to airspeeds via winds and TAS shows IAS around 60knots for quite some time before departure from controlled flight. During the last 30s before it went south the aircraft climbed further despite being on what seems to be a drop final @ altitude and being cleared for drop and descend.
After this there is a very sharp around 150 degree course change to the left and simultanous steep descend and speed increase. The dive angle is around 60 degrees( horisontal distance / vertical distance) and after the sharp 150 degree left there is a vide left turn( almost straight) still with 60 degree dive angle and speed increasing. The ROD is 16000fpm or more.
This aircraft had Mode S and at around 2300m altitude( webtrak shows altitude in meters) all horisontal speed disapears and the heading starts rotating until data is lost. There is also a loss in vertical speed and forward speed.

This, together with the withdrawal of the AD groundning the Ga-8 points in the direction of stalling, inadvertant IMC, high speed dive and overstressing the aircraft when getting visual with ground beneath clouds.
AAKEE is offline  
Old 27th Jul 2019, 14:46
  #22 (permalink)  
 
Join Date: Apr 2001
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Thanks for that AAKEE, it does paint a picture, a rather grim one. Suddenly finding yourself in a spiral dive in cloud with spatial disorientation for the first time is quite a moment. The temptation to pull must be resisted.
​​​​​It's still speculative but it does fit.
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Old 30th Sep 2019, 13:21
  #23 (permalink)  
 
Join Date: Jan 2006
Location: up there
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Swedish Airvan Crash

A possibility.
Given a stall scenario one can see all the jumpers crowding around the door. The aircraft stalls and the nose pitches down. All the jumpers fall into the forward cabin in a mass of humanity. They are all over the pilot. He is unable to raise the nose because the CG is far too far forward. The jumpers are all unrestrained as they crowd towards or are at the door.
The aircraft accelerates beyond its VNE and a wing fails followed by the tail. It then is held in place by the control cables as was seen in the before impact photos.
A possibility.
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Old 30th Sep 2019, 17:34
  #24 (permalink)  
 
Join Date: Nov 2005
Location: Zulu Time Zone
Posts: 645
.....hmm. I have done many stalls in the Airvan. It is benign, often there is no nose drop at all and it will just mush down. It can be quite difficult on a check ride or a C of A to be sure it has stalled until a noticeable rate of descent is indicated. Also it is very hard to get the cg out of forward limit and a pile of pax behind the two front seats would not do it. Furthermore, the seat backs are pretty substantial. They are higher than ie a 206. Of course it would still be possible in extremis for a pax to come over the top of one at shoulder level and there is also a gap between the seats that a person can climb through. However I really don't think the above scenario is at all likely to be caused by the non-event that is a stall in an Airvan.
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Old 2nd Oct 2019, 14:12
  #25 (permalink)  
 
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I spoke briefly to a sky-diving instructor mate of mine this morning. He mentioned devices called AAD's . Automatic Activation Devices (I think that was what he said). Basically an unconscious sky-diver in free fall passes a threshold altitude without popping his canopy and the AAD pops the reserve automatically. He has seen the video and suggests that the rate of descent would trigger these on the packs of the occupants. This might explain what looks like a candled canopy and the eyewitness reports of the skydivers attempting to get out of the aircraft. I don't know enough about these bits of kit but assume that they can be de-activated or the pilot ensures a reduced decent rate close to the the trigger altitudes to prevent them going off unintentionally when returning to land with pax still on board. In this tragic accident, I doubt anyone on board had chance to deactivate them if that is the case.

Anyone know any more about parachuting safety gadgets?
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Old 2nd Oct 2019, 19:01
  #26 (permalink)  
 
Join Date: Jan 2009
Location: Sweden
Age: 52
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Preliminary out

The preliminary report is out.

Preliminary report
There was no chute outside but all of the Cypresses/AAD did deploy the chutes.

The aircraft did loose one wing ( also complete tailplane was lost) and was ”spinning” with the wing still attached upwards and fuselage horizontal.

The airspeed was very low before the departure and aircraft was climbing while loosing speed. The pilot did ask for higher altitude to clear clouds shortly before.

There was clouds from around 7-8000feet and appearently up to drop altitude(4000m).

The engine did have power on during the accident and did reach 3100rpm. VNE was exceeded.

There was some kind of missmatch with Swedish CAA, MTOW was registered as 1814 kg but the owners say tjey had the STC for 1905 kg incorporated.
The weight at accident time is cslculated to 1904 kg so they must have had some overweight until just before accident even if 1905 is valid. ’Havkom’ also calculated CG to be around 15-20mm aft of CG limit.
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Old 7th Oct 2019, 18:20
  #27 (permalink)  
 
Join Date: Apr 2001
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I'm out of touch with the allowed MTOW of the Airvan but 1814 I seem to remember was the original MTOW. That has been increased since. So it's unlikely a factor in the accident. In terms of CofG. When empty or light in Airvan you'd run out trim and have to hold back pressure on approach. To me that implied it was designed to be slightly nose heavy. Further confirmation of that was the fact we always asked one of skydivers to sit on the step at the rear because it helped stability.

As oggers said the stall is benign and the warning horn comes on much too early. I was only caught out once when all the skydivers rushed the door simultaneously without briefing me. But it was easy to recover from and also remember ailerons can be used right through the stall. It essentially mushes downward.

While a botched stall recovery is a possible cause. I return to the idea of a spiral dive through VNE possibly because of a distraction or spatial disorientation. It happened to me. I turned to talk to a skydiver. When I looked back the airspeed was in the yellow and the VSI was pegged at it's limit. Instant disorientation. I reduced power, levelled the wings and eased very gently out of the dive having now entered cloud. Then I started breathing again. The crew in the back noticed nothing. Boy did I feel stupid. A panicked pull and the story might have been quite different.

Someone asked about the AADs. They will fire at a predetermined rate of descent below a set altitude. That can vary, student rigs have a more conservative setting. In fact I was in the back wearing a student rig on a ferry flight when the pilot forgot and dived off the altitude. There was a bang and I was surrounded by canopy. He was mortally embarrassed. But I could have deactivated it if I'd known he was about to play fighter pilot.

The skydivers were probably pinned to the floor or ceiling by the time the AADs fired. No chance.

The pilot I note had only 12 hours on type and 214 in total. No mention of an instrument rating. Maybe it was the first time he found himself in the conditions he encountered that day.

An odd comment in the report. It mentions standard procedure is to close the cowl flaps before the descent. The Airvan doesn't have cowl flaps.

Also no mention of cameras, no GoPros? That would be a surprise.

Last edited by Steepclimb; 7th Oct 2019 at 18:52.
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Old 7th Oct 2019, 20:20
  #28 (permalink)  
 
Join Date: Jan 2009
Location: Sweden
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The cowl flap thing might be some kind of relic text from another aircraft I guess. I dont remember what they had before but maybe a C206?

Pilot, as far as I read he had no IR-rating and it seems from other forums like most of the pilots flight time was some years back, not much recent. He was new on the diverdriver thing.

How would the Airvan handle in a power on stall ?
The pilot asked for higher climb ( due to clouds) and the data shows a climb with speed decreasing(down to or below stall speed) before the abrupt dive and change in direction.

There seems to be no recording available. The departure from controlled flight was somewhere around 1.25Nm before overhead and probably above clouds so they pergaps hadnt turned the cams on?



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Old 9th Oct 2019, 22:21
  #29 (permalink)  
 
Join Date: Apr 2001
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My experience of a power on stall in the Airvan with a full load was essentially a non event. But a mishandled recovery and a low time non IR pilot.......

As I said it went from situation normal to a spiral dive was very quickly. My training was good and I simply recovered.

Perhaps he didn't have that luxury.
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