2000 ft. Density Altitude contributing factor?

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Rich
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2000 ft. Density Altitude contributing factor?

Post by Rich »

I was looking at an DA40NG accident in Florida last year. Here was the probable cause from the NTSB:
The pilot's delayed decision to go around in high-temperature and high-density altitude conditions and his exceedance of the airplane's critical angle of attack, which resulted in an aerodynamic stall.

Also from this report:
... and the density altitude was 2,000 ft.

Out West we are used to DA's commonly beyond 5,000 ft. But almost anywhere in the country for a goodly portion of the year 2,000 ft. and more is the norm. Pretty much everyone deals with some amount of DA effect above field elevation all the time. Why it's included as a contributing factor is beyond me. :scratch:
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rick
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Re: 2000 ft. Density Altitude contributing factor?

Post by Rick »

Yeah, that's a head-scratcher for sure. My 1200' field spends most of the summer at DA's of 2k or above. I would think 2000' is about normal for most of the US, and just a dream for many western pilots! It sure doesn't seem worthy of mention as a 'contributing factor'... :scratch:
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Boatguy
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Re: 2000 ft. Density Altitude contributing factor?

Post by Boatguy »

Yes, that makes no sense, especially for a DA40NG. The difference between climb performance at SL vs 10,000' is just 55fpm. The difference between SL and 2,000 is 7fpm!

Do you have a link or tail number for that accident?
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Rich
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Re: 2000 ft. Density Altitude contributing factor?

Post by Rich »

Boatguy wrote: Fri Jun 26, 2020 5:17 pm Yes, that makes no sense, especially for a DA40NG. The difference between climb performance at SL vs 10,000' is just 55fpm. The difference between SL and 2,000 is 7fpm!

Do you have a link or tail number for that accident?
https://app.ntsb.gov/pdfgenerator/Repor ... L&IType=CA
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: 2000 ft. Density Altitude contributing factor?

Post by Boatguy »

The pilot landed with an 8kt tailwind on a grass runway. The AFM adjustments for tail wind and grass say that landing was doomed.
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Rich
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Re: 2000 ft. Density Altitude contributing factor?

Post by Rich »

I did a last-second go-around in almost identical atmospheric conditions years ago. Crosswind changed to tailwind right before flare on a 2,000-ft. strip and 80-degree day. When the plane was just past halfway down the runway I could see it wasn't happening. I slammed the levers full forward and went around. Differences from this accident:

- I was at roughly 2200 lb.
- Left full flaps in.
- The obstacle I had to clear was a towering bunch of blackberry bushes about 12 ft. high right off the departure end of the runway. I aimed the nose just high enough to clear them. Never got anywhere near a stall.

When slamming stuff full forward my engine/prop goes from idle to full power almost instantly. I don't know if the lag in the NG referred to in the accident report is accurate, but I have seen this in other turbocharged aircraft, where the turbine has spun down and takes a second or two to spin up. Nevertheless, the big deal was the delay in taking action by the pilot. If DA is to be considered a factor here then it'd be a factor in almost every such accident in the country. :scratch:
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: 2000 ft. Density Altitude contributing factor?

Post by tahoemark »

Well, pilot with 127hrs in over his head with bad decision making. I made some rookie mistakes myself, fortunately never damaged airplane or crew.
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