New AOPA/ASI accident analysis video • Into Thin Air

[Garfly]

 

 

 

[turboplanner]

Density altitude is a simple pre-flight calculation.

Just a hot day at normal altitudes can cause problems.

How many opetions did this guy have to abort.........

 

 

[Garfly]

1 hour ago, turboplanner said:

Density altitude is a simple pre-flight calculation.

It appears from the AOPA vid that those (experienced) Bonanza pilots were far from clueless regarding 'simple pre-flight calculations' regarding DA.  (So perhaps a bit unlike the Stinson case.) They came across as very aware of the performance issues they faced.  The film suggests it was, rather, the not-so-simple DA considerations (wider turning circle, higher ground speed) plus 'unfamiliarity' with the place and mountain flying in general (including how sight-pictures should look) that caused the downfall of these two, otherwise competent and careful, guys.  That's the take-away for me. 

 

 

 

 

 

 

 

Edited December 10, 2021 by Garfly

[facthunter]

Good article covering most aspects of it. DA IS a simple calculation and the more information you have the more accurate the result. Just having a DA is not enough unless you are familiar with how your particular plane performs at that DA. Also with the C/S prop your engine output cannot be precisely determined. It could be down on power but no mag drop so  it could fall well short of new performance.

   An orbiting climb over the airport is a good idea for several reasons. One being that you can return to that drome if you have an engine fail during a greater part of the flight than otherwise.

    Estimating the height of a distant ridge is difficult and often erroneous. To know the minimum height and your G/S would enable  a better assessment of your certainty of clearing it,  on a running basis that left more room to do a safe turn.. Being in the middle of the valley sealed their fate but the wind from  where it was could have done that as well even if they had been in a better position, altitude wise.  You should operate to clear such ridges by a fair margin rather than just enough whenever winds are unfavourable. Your plane has little performance above just keeping itself in the air.Nev

[F10]

Unfortunate when you see how many chances the Stinson pilot had, to land back straight ahead. When you get airborne and climb out of ground effect, with full power, you stop accelerating or RoC reduces to less than 200’/min…you are in trouble. You are forced landing if terrain is rising. This is hard to accept, but better to fly it in under control, rather than becoming a passenger along for the ride.

[facthunter]

You are out of ground effect with the Stinson at tree top height.. Nev

[kgwilson]

As the narrator stated by the time he'd got to treetop height there were no options left. The big mistake was continuing after the initial drop back onto the strip. The Bonanza pilot obviously had no mountain flying experience. Straight up the middle is asking for trouble and he would have known the climb rate was poor the whole time. Just making it over a mountain pass at that altitude is also asking for trouble given the performance of the aircraft at the time. Another orbit or 2 & he'd be home free.

 

If I am heading across the Great Dividing range and there is a Westerly, I like a 3000 foot buffer between me and the highest terrain. If I am going to Armidale from South Grafton the direct path is close to Mt Hyland (4,705 feet) & Round Mountain (5,204 feet). To me that is at least 8000 altitude so 8,500 hemispherical.

[Garfly]

Another new video about a similar accident in The Rockies around 50 years earlier.  This one, made by the Aussie air crash re-construction YouTuber, "3 Greens - Aviation Safety"       https://www.youtube.com/c/3Greens/featured) 

 

 

 

 

 

[F10]

Yep, stuff taught to me military chopper flying. Never fly through a saddle or over a ridge unless you can climb enough to clearly see the terrain on the other side. Always cross a ridge at 45 degrees to it, so you can easily break away if need be, as you approach. Reading the wind is vital, hitting a strong downdraught can rapidly eat up any access climb performance, or cause a involuntary descent. 

Ground effect is theoretically 3/4 wingspan, practically more like 1/2 wingspan height. The Stinson pilot had a thousand chances to land back, before he was over the trees, when it was too late. He must have realised long before that, he was on the edge of the aircrafts performance. Full power and the airspeed indicator is hovering at your rotate speed, with no signs of acceleration or the VSI shows no appreciable rate of climb, and you are in deep doo doo. Any attempt to turn with more than about 10 degrees AoB, will increase doo doo depth further….if you have rising terrain ahead….