4th Aug 2018 Junkers JU52 crashed in Switzerland

[spoon84]

There was a statment today in the media of the owner of a mountain lodge of the Segnespass, which said that it was everything normal as the airplane always did, but after a left turn (completed) the plane just fall off the skies like a stone. He also said that there were people at about 150 . 200 meters of the crash that were in his lodge. He did went there to assit but everyone was dead.

You can check the Mountain Lodge here: Segnespass

and the news here: https://www.tio.ch/svizzera/cronaca/...come-un-sasso-

[Alpine Flyer]

An undated (and probably reprinted) factory sales brochure for the Ju52/3m lists the following data:

1980hp total for 3 BMW 132A engines

service ceiling 19030ft (20350 with variable pitch props), OEI 9520ft (10830 with variable pitch props)
(Can't tell from online pics whether props are variable or fixed pitch, looks more like the latter and absence of manifold pressure gauges on flight deck pics would also hint at that.)

MTOM 10t (22000lb.)

[pattern_is_full]

Just a reminder - since it hasn't been mentioned yet - that what counts in a stall is AoA, not a particular speed. Making a 180° turn in a narrowing valley may require a rather steep bank to avoid the valley walls, with associated G forces (accelerated stall). If there is altitude below one, one can unload the wing a bit with a descent in the turn (a bit of forward stick to lower AoA). But maybe the space isn't there.

The crash location (see top photo post #51) looks like a classic "box canyon," which have killed many fliers, and even if the "numbers" say it should be a piece of cake (ein klacks?) to outclimb the terrain, factors such as +ISA, downdrafts or other turbulence, the angle of the valley floor, weather seen on the far side of the ridge or pass, etc. can all cut off one's options rather rapidly. Even a competent, experienced pilot/crew can get trapped, if the holes in the cheese line up fast enough.

I am - equivocal - about machinbird's image and analysis. Only because I know how much a telephoto lens' compressed "perspective" can sometimes distort visual geometry, and because without motion, I am not full persuaded the "smoke trail" is not, perhaps, a highlight on the exposed mountain rock in the background, or other artifact. It is suggestive, but not definitive.

The observer descriptions (however flawed) and the aircraft condition/position are strongly suggestive of a stall/spin.

I'm also not persuaded by the idea that the terrain was suitable for a survival emergency landing. The terrain immediately around the crash site is even, but there may be a substantial "flat" downslope that would make braking and deceleration difficult, and of course even a Junkers doesn't land like a helicopter - it takes several hundred meters/yards of rollout, and who knows what obstructions, dips and boulders were "just outside the frame" in the photographs. I live and fly in the Rockies, and there many places above the tree line here (tundra) that "look flat" from 1000 feet AGL, but would be disastrous to actually try and land and stop on.

The only person I knew personally, who died in an aircraft accident, died in a direct dive into mountain valley terrain. Very similar to this accident. He was a pilot but acting as a photographer in the right seat when he died. His last pictures showed they were low over trees, straight and level. Exactly what put them into a dive was never determined.

[Airbubba]

I had a colleague do an approach to stall with pax onboard in an A310 over the Alps years ago. He wanted to show the folks some scenic alpine valley and got permission from ATC to do a couple of orbits. He turned off the autothrottles and autopilot and wrapped up the bank as he looked out to keep the landmark in view. Nobody was minding the store and the airspeed dropped until the red bars came up on the PFD tape and alpha floor was triggered. The throttles automatically reengaged and went to full TOGA thrust.

The A310 is somewhat overpowered and short-coupled for a widebody and the pitch change when both engines come up is impressive. After some minor aerobatics control was restored and the flight continued on its way. No harm, no foul except a fed and his wife were onboard in the back and reported the incident. The TXL-based crew got first class tickets to MIA for some extra sims.

[beamer]

Originally Posted by pattern_is_full

Just a reminder - since it hasn't been mentioned yet - that what counts in a stall is AoA, not a particular speed. Making a 180° turn in a narrowing valley may require a rather steep bank to avoid the valley walls, with associated G forces (accelerated stall). If there is altitude below one, one can unload the wing a bit with a descent in the turn (a bit of forward stick to lower AoA). But maybe the space isn't there.

The crash location (see top photo post #51) looks like a classic "box canyon," which have killed many fliers, and even if the "numbers" say it should be a piece of cake (ein klacks?) to outclimb the terrain, factors such as +ISA, downdrafts or other turbulence, the angle of the valley floor, weather seen on the far side of the ridge or pass, etc. can all cut off one's options rather rapidly. Even a competent, experienced pilot/crew can get trapped, if the holes in the cheese line up fast enough.

I am - equivocal - about machinbird's image and analysis. Only because I know how much a telephoto lens' compressed "perspective" can sometimes distort visual geometry, and because without motion, I am not full persuaded the "smoke trail" is not, perhaps, a highlight on the exposed mountain rock in the background, or other artifact. It is suggestive, but not definitive.

The observer descriptions (however flawed) and the aircraft condition/position are strongly suggestive of a stall/spin.

My thoughts were the same. The terrain looks challenging and visual illusions are all to easy to encounter. A 180 turn to escape from a box valley could be very challenging in an old aircraft even for very experienced pilots.

[Blohm]

Originally Posted by weatherdude

No, this is not the true. The max gust at Crap (Rock) Masegn at the time was a Max of 48 kph Hourly gusts in the area

I don't know the true, but what is kph? Kilometers per hour, as in kmh or is it kts? (Natical miles per hour). I am used to kts in this context.

[Machrihanish]

Originally Posted by Blohm

what is kph? Kilometers per hour

This.




_

[DaveReidUK]

Originally Posted by ZFT

I was lucky enough to fly on a B17 and no one dared question my ability to determine if it was safe.

That doesn't necessarily mean that your determination was sound. It may have been unsafe, but you were (in your own words) "lucky enough".

[ORAC]

Valleys bite.

ASN Aircraft accident Lockheed Hercules C.3P (C-130K) XV193 Blair Athol

[weatherdude]

Originally Posted by Blohm

I don't know the true, but what is kph? Kilometers per hour, as in kmh or is it kts? (Natical miles per hour). I am used to kts in this context.

=Kilometers per hour. Divide by 1,852 for knots.

[ATC Watcher]

I do not buy the sudden CB blocking the way , the 180 in a tight valley and the subsequent stall. Those guys were not amateurs ,they were locals to the area and knew the aircraft well. Anyone flying deep in the Alps knows how and when to go back ( and how to do, or not to do , a 180 in a valley, and with such a slow aircraft should not be a real issue anyway ),
The aircraft might not have radar but today with an IPad and Meteox you know exactly where the cells are and where they go . Finally a stall in a Ju52 would not pitch down the aircraft to a vertical dive as suggested .

[BARKINGMAD]

Neill Williams some years ago?? And he was more of a "raw" flyer than 2 very experienced 'bus' drivers? ��

[ZFT]

Originally Posted by DaveReidUK

That doesn't necessarily mean that your determination was sound. It may have been unsafe, but you were (in your own words) "lucky enough".

So you are questioning it?

I also thought it was pretty obvious the luck was referring to the event, not the survivability of it!

[weatherdude]

Radar

This is a very funny idea that you want to see TCU and showers just starting on the ridiculously bad resolution (4 to 8 times worse than the real thing) on Meteox.

Originally Posted by ATC Watcher

I do not buy the sudden CB blocking the way , the 180 in a tight valley and the subsequent stall. Those guys were not amateurs ,they were locals to the area and knew the aircraft well. Anyone flying deep in the Alps knows how and when to go back ( and how to do, or not to do , a 180 in a valley, and with such a slow aircraft should not be a real issue anyway ),
The aircraft might not have radar but today with an IPad and Meteox you know exactly where the cells are and where they go . Finally a stall in a Ju52 would not pitch down the aircraft to a vertical dive as suggested .

[ATC Watcher]

This is a very funny idea that you want to see TCU and showers just starting on the ridiculously bad resolution

It is quite accurate in central Europe and we use it, combined with sat 24 , and it works quite well but mostly to delay take off or change routings, but not to circumnavigate cells as you do with an on board radar,
If you do not have on board wx radar meteox is a good tool to keep you out of trouble.

[gearlever]

Today BAZL cancelled ban on JU 52.
JU-AIR resuming flights per 17th August.

Hhm, does this mean BAZL know already what went wrong?

[Armchair_Ace]

This was the aircraft used in the movie Where Eagles Dare. Swiss Air Force A-702. Tragic loss of life.

[weatherdude]

Again, the echoes in my earlier post never showed up. Also try to see small areas like those in the blog post on sat24

Blog with satellite and radar links on weather/crash site

Originally Posted by ATC Watcher

It is quite accurate in central Europe and we use it, combined with sat 24 , and it works quite well but mostly to delay take off or change routings, but not to circumnavigate cells as you do with an on board radar,
If you do not have on board wx radar meteox is a good tool to keep you out of trouble.

[Machinbird]

Originally Posted by ATC Watcher

Finally a stall in a Ju52 would not pitch down the aircraft to a vertical dive as suggested .

I sort of agree with you. an aggravated stall will not bobble the nose up and down the way AF447 did. Instead, an aggravated stall will induce a roll to inverted and the aircraft will dive. These older aircraft typically have rather rapid roll off in a stall.

In earlier posts, I mentioned the downward curvature of the vapor trail in the screen grab. This indicates steepening of the flight path, which if while maintaining a constant attitude, results in an increasing angle of attack. This was a 'gotcha' that D.P.Davies warned of in his book,"Handling the Big Jets." It would seem that the warning also applies to piston aircraft operating near their ceiling.

I too wondered whether the screen grab was significant since it was described as a picture of the aircraft shortly before the crash. When I saw the degree of angle of attack on the aircraft, it was clear that the aircraft was in extremis if the vapor trail was what it appeared to be. Following the vapor trail back, it became semi-transparent as a real vapor trail would. The fact that someone had already circled it meant that it was likely significant. Finally, did you ever ask why we only have a screen grab instead of the original video? I think it likely that the video would have been very distressing to those who saw it, but you can bet the accident board has seen it.

[Skyborne Flyer]

Originally Posted by Machinbird

In earlier posts, I mentioned the downward curvature of the vapor trail in the screen grab. This indicates steepening of the flight path, which if while maintaining a constant attitude, results in an increasing angle of attack. This was a 'gotcha' that D.P.Davies warned of in his book,"Handling the Big Jets." It would seem that the warning also applies to piston aircraft operating near their ceiling.

I too wondered whether the screen grab was significant since it was described as a picture of the aircraft shortly before the crash. When I saw the degree of angle of attack on the aircraft, it was clear that the aircraft was in extremis if the vapor trail was what it appeared to be. Following the vapor trail back, it became semi-transparent as a real vapor trail would. The fact that someone had already circled it meant that it was likely significant. Finally, did you ever ask why we only have a screen grab instead of the original video? I think it likely that the video would have been very distressing to those who saw it, but you can bet the accident board has seen it.

I believe the video was said to be of a previous flight, a previous poster stated that the view is from a different region, that the accident flight did not traverse, and therefore has no bearing to the chain of events leading to the crash.