Val d'Anniviers Airplane Crash

[IO540]

Can anyone post the coordinates?

[englishal]

I don't reckon a rotor would do this. Looks to me they hit nose down - in fact almost "flopping" onto the ground in a very hard impact. In a down draft the nose would be up, but in the picture the tails is in perfect shape, with heavy damage to the front / wings (look how flat they are but not bent backwards) so I agree with IO that they were nose down with low forward speed, high vertical speed so probe noably stalled before thse went down.

Actually those pictures are pretty shocking. I don't recommend anyone lets their partners see them or they will never get in a light aeroplane again. I am just glad that it would have been quick judging by the damage.

[vanHorck]

File:Pointe de la Forcletta - Depuis Sorebois.jpg - Wikimedia Commons

This is a picture of it as well as a correct spelling, it has nothing to do with the col de la Forclaz

IO pls check your mail

[blueandwhite]

I was taught to approach and cross a ridge at about 45 Deg angle. So if you got downdraft or another plane coming the other way you only have to turn 45 Deg to avoid crossing if needed. Maybe this is what was involved?

As far as how close to the ground to get downdraft or updraft. I was shocked. My instructor expected me to fly within feet of the side of the valley to get full benifit of the updraft. He did say not to get closer than about 10 feet (he did say feet dispite being French)

Mountain flying and landing on "imposible" spots - best flying I have ever done

[IO540]

vanHorck - I found that ridge OK in google earth but none of the background views match those in the crash photos.

I was wondering what could have caused the roof to blow upwards like that, rip out the roof pillars, and to eject the two seats. I reckon an oxygen cylinder blew up. Car bombs do the same thing - the roof looks curved. Must have done so after the impact because one of the seats ended up on top of the wing.

[LH2]

Originally Posted by englishal

In a down draft the nose would be up

Not if you're stalled. Then you go down like a sack of potatoes you do.

[SkyHawk-N]

Looks like an accident due to a ridgeline downdraught to me. Rotors develop below ridgeline level and away from the terrain. Sounds like the winds were strong enough to have easily caused a problem, remember that winds will be significantly stronger (maybe more than 2x) crossing high terrain like that.

I've been through severe mountain downdraughts a few times, one time my VSI maxed out (2,000ft/min downwards) instantly.

[cats_five]

An updraft would increase AoA and can cause a stall, depending of course on how fast they are flying.

[hambleoldboy]

I reckon the crash site is on the ridge running to the north from the Forcletta pass to the peak 'Le Boudri'.



The village visible below the crash site is probably Ayer.

Maybe I'm completely mistaken, in any case this site will publish a preliminary report in a few days:

BFU - BEAA - UIIA - AAIB

The general wind was south westerly, this is known in the Alps as 'Foehn' and can be unpleasant, but on the morning of the accident winds were not strong enough to produce significant downdraughts or rotors. They were certainly not a problem where I was flying 100 miles further east.

From the Forcletta the ridge rises to the south east up to the Weisshorn at over 14000ft.

[SkyHawk-N]

Winds were SSW 15-20Kt between 8,000 and 13,000ft.

If these were the winds at the time I would have thought that they could be strong enough to cause an issue in the mountains. My rule of thumb is for 20kt winds I would need to clear a ridgeline of 9,000ft by 1,500ft+ minimum, and ideally 2,000ft+. Obviously it depends on the direction of the wind in relation to the ridgeline, my figures are for where they are perpendicular.

[BackPacker]

I would think that the flash memories of any installed GPS set

My eTrex keeps a track log, but do GA GPSs (like the Garmin x96 or x30 range) do that too? I've never seen that.

[IO540]

Winds or mountain waves cannot explain why this plane hit the ground with zero apparent forward velocity.

FWIW, my rule of thumb for a 500fpm up/downdraught is 1000ft above the peak(s) for every 10kt of wind aloft.

Crossing the Alps, I would normally be at FL160-190 which tends to be at least 5000ft above the terrain. I have never seen any significant turbulence. The worst I have had was a boat-like ride which was disconcerting to my lady passenger but, with the autopilot holding altitude, there was no apparent variation in speed.

Normally, entering e.g. a downdraught, and using the AP to hold altitude, you see a airspeed drop and a pitch-up, obviously. I've seen plenty of those, and also the opposite. But I don't cross the Alps in poor weather, and neither was this pilot. Also, the ridge was some way from the nearest other ridge and I can't immediately see how one could end up where he ended up purely as a result of turbulence (a rotor, etc).

[IO540]

No IFR GPS unit I know of keeps a track log.

[S-Works]

I am curious why you think zero forward speed?

[Deeday]

My humble Garmin 196 does keep a track log, with a selectable resolution whose factory default is one point every 30 s.
There are a few AAIB accident reports that include track logs downloaded from portable GPS units, although in many cases the owner never modified the default resolution, making the log not as helpful as it could have been.

[englishal]

I am curious why you think zero forward speed?

No apparent backwards bending anywhere, the wings are completely flat yet still "connected", no apparent disturbance immediately behind the aeroplane etc.

In a down draft you'll be trying to climb, which is why the nose would be up. If you stall, well, that is just bad piloting, but if you didn't and you hit the ground it would be in a nose high attitude.

15-20 kts shouldn't give too many problems around mountains, especially if clear of them by >1000', it might be a bit bumpy but I wouldn't have thought that there was anything nasty enough to cause this crash.

[IO540]

Accidents involving "more advanced" aircraft do tend to draw attention (here, anyway) because pilots of those types are more interested in learning from others' mistakes. If somebody prangs a C150, it doesn't draw much attention. Whether a pilot of a Baron is necessarily any more smart than a pilot of a C150 is another matter (probably not, but he ought to be).

In a down draft you'll be trying to climb, which is why the nose would be up

If trying to hold altitude, sure.

I saw the MSLP chart for the time but haven't got it saved. It didn't show much wind.

[tdbristol]

G1000 can do track log

Not really relevant here, but FYI if you plug an SD card into the top slot of the MFD in a G1000 it records just about everything, once per second. (Time/date, Lat/Long, IAS, TAS, pressure, heading, altitude, vertical speed, wind speeds, fuel pressure & flow, engine rpm, oil pressure, engine temps, roll, pitch & yaw attitudes and rates...).

This may very with software version, but works in my DA40 (useful for monitoring performance over time - hopefully it won't ever be needed for post-accident but clearly pretty helpful for that, assuming the SD card survives).

[LH2]

Alan,

Originally Posted by englishal

In a down draft you'll be trying to climb, which is why the nose would be up. If you stall, well, that is just bad piloting

I do not think you appreciate what a sudden change in AoA to a high negative number will do to your flying.

Forgot to say, in a forceful downdraught, your strategy is to maintain airspeed first, then get out--normally by turning downhill. Trying to climb is not normally an option.

[Barcli]

There is a ( now) mandatory Beechcraft AD requiring the replacing of the lower wing bolts and a mod to the lower wing bolt attachments in the spar - All B55/B58 types now HAVE to comply - could we be looking at the first in flight failure of such bolts - wings pivot upwards = high rate of vertical descent ala leaf ?