Originally Posted by
john_tullamarine
my approach would be to use a higher altitude/lower temperature giving the same density altitude and enter the chart that way.
On what basis ? Not being wary of extrapolating to higher elevations and OATs might present problems. Things aren't necessarily linear.
For the typical non-engineering pilot, I would suggest don't extrapolate high. If the elevation/temperature is lower than the the chart data, and there are no other systems limitations prescribed in the limitations section, maybe .. and, in that case, use the published data without trying to take advantage of extrapolation.
Yes indeed. Years ago, I had an old model 172 at 6500 ft pressure altitude and 85 deg F. I spent a lot of time cogitating on the takeoff distance and, especially, the climb performance. I had enough information in the manual to indicate that it would be OK but it would not have achieved CASA's requirement for 6% gradient. This was in another country with no such requirement.
Originally Posted by
john_tullamarine
I would be interested in djpil and JT comments.
I think Dave and I would opine along the lines that we would, .... reschedule the performance data .. get a tick in the box .. and Robert's your parent's sibling.
Yes indeed. American AFM's were not intended to specifically provide the data required to determine takeoff weight etc per CAO 20.7.4. So, if one cannot determine the weight at which both runway distance is adequate and climb gradient is 6% then you shouldn't go.
Of course, Kaz can use trial and error in the Auster to determine it.