Lest you think you can beat density altitude!

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Lest you think you can beat density altitude!

Postby eaglepilot » Wed Aug 08, 2012 3:56 pm


So that we can all learn-

From another site:

"The video seems to document an accident in ID in June. The aircraft in that accident was a Stinson 108-3.

According to reports, the departure airport was Bruce Meadows Airport (U63), Stanley, Idaho, elevation 6370.

The investigation has only begun, but the video appears to show one hazard associated with operations at high density altitudes, viz., that you may be able to take off, but you may not be able to outclimb terrain and obstructions."

The video is chilling in how benign it seems until there is a problem.....


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Re: Lest you think you can beat density altitude!

Postby WiredforFlight » Thu Aug 09, 2012 12:02 am

there is an NTSB prelim. http://dms.ntsb.gov/aviation/AccidentRe ... 120000.pdf and here is a bunch of napkin math http://www.reddit.com/r/aviation/commen ... if/c5q19tz

more or less looks well over loaded, very high density altitude, and totally should have aborted takeoff long before he lifted off.

NTSB pulled PDF for some reason http://www.ntsb.gov/aviationquery/brief ... 5804&key=1

NTSB Identification: WPR12LA283
Aircraft: STINSON 108, registration: N773C

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Re: Lest you think you can beat density altitude!

Postby nmontei » Fri Aug 10, 2012 10:18 am

Even if the guy was not intelligent enough to do a weight and balance and he didn't realize his takeoff was way too long, he still had a lot of time to put it down in the grass before he got to the trees when he realized he was not climbing.


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Re: Lest you think you can beat density altitude!

Postby champguy » Fri Aug 10, 2012 9:07 pm

Many planes do not have sufficient documentation to perform a useful takeoff performance calculation, particularly when you consider that there is no useful way to include the drag of a mountain "grass" strip.
There are however useful emperical devices. The TOP slide graphic computer is such a device. It is calibrated for your plane with your flying skills, then can be adjusted for various changing conditions.
The Mountain Flying Bible, by Sparky Imeson, is an invaluable study before heading out over and into the wilderness. http://www.mountainflying.com/products/mfbr_info.html
One "rule of thumb". Mark the midpoint of the runway. If, as it goes by, you haven't got three quarters of the airspeed you will need to safely climb, quit while you can still stop. By marking the mid point, and using indicated airspeed you have removed all the variables that, in the real world, you really can't calculate anyway.
Unless the field is really short, a full power runup is too dangerous to the prop or horizontal stabilizer. After you are moving, then apply full power and adjust the mixture for peak power. Pay attention, and be ready to quit while ahead.
Remember, not all who wander, are lost.

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