On Jul 17, 3:09*am, Bruce Hoult wrote:
On Jul 17, 6:19*am, Chris Donovan wrote:

*the FAA inspector arrived,
without so much as 5 min passed and he prononced "Pilot Error," it was
a horrific crash of a single engine light plane. *How could he make
such a snap decision I wondered... Untill He explained..."four
adults...golf clubs...fulll tanks." *you don't always have to get
eyewitness reports and measure distances and etc., *because there
isn't a light single, (172, Cherokee class) that can leave the
ground...ever...that heavy!!! *

Hmm.

http://en.wikipedia.org/wiki/Cessna_172

Empty: 1691 lb
Gross: 2450 lb
Rate of climb: 721 fpm (at gross as these things are)

Useful load: 759 lb.
Fuel: 56 USgal, 212 litres ~= 170 kg, 374 lb

Four adults and golf clubs? Maybe 800 lb?

So It'll be overloaded by about 415 lb, weighing a total of about 2865
instead of 2450, or about 17% overload.

I find it very hard to believe that an aircraft that can climb at 721
fpm at gross weight can not fly at all with a 17% overload!

Use more runway, sure. Climb slower, sure. But not fly? Inconceivable.

It's not that simple. Using your estimated 415 Lb overload and an
estimated C172 L/D of 7 works out to need 60 pounds-force more thrust
at the airframes best L/D airspeed of roughly 65 knots. (Extra weight
divided by L/D = extra thrust required) Since the stock fixed
propeller is optimized for cruise flight, it will be operating well
off its best efficiency so that 60Lb-f of extra thrust needed to fly
will be hard to get.

Depending on the density altitude, it's entirely possible the
overloaded airplane wouldn't fly out of ground effect. It's a classic
C-172 accident scenario seen in hundreds of accidents across the
western US. This FAA inspector had probably seen way too many of them
and was feeling understandable frustration and anger.

Gross weight limits must be respected.

Bill Daniels