The International Cessna^® 170 Association

One other thing to remember in high D/A is that the controls are just as starved for "good" air as the wings and prop blades. Controls are less effective on those "high/hot" days.

I'm glad George revealed the same sort of experience he had at Winslow, AZ that we had at Gallup, NM. Rising terrain in those two airports are similiar. I made mention of the "down hill" run at Taos. It is much the same at Winslow and I forever prefer a little (VERY LITTLE) tail wind and downhill every time. My Mom and Dad lived about 50 miles NW of winslow at Leupp, AZ. There is a little gravel strip, about 5000' long' at that village and I usually had to shoo the livestock off with a couple of low passes. I will tell you one thing though, we never tried to take off in the heat of the day!

Flaps on takeoff- - - - In my experience putting flaps into the mix just added another thing to slow the plane down. Any D/A over 8000' requires the plane to be in the "cleanest" configuration possible to be able to accelerate to "safe" flying speed. Any added drag at high D/A just exacerbates the problem the plane has in reaching "safe" flying speed.

Remember George's formula for horse power/RPM. Well if your C145/O-300 isin't turbocharged cut the factor by 15% at 9000+ D/A. Even if we had "all" 145 ponies pumping at full effeciency, we would be really pushing the envelope at high D/A. I WOULD BET THAT IN REALITY , WE ARE BORDERLINE IN EXPECTING 100hp.

I've been into Aspen (before it became mega-buck haven), Leadville, Telluride, Durango, Pagosa Springs and Alamosa. No time in any of those Rocky Mountain "box canyon" airports, all over 7500' MSL, did I ever encounter the D/A problems I have had at the High Desert airports in Arizona, New Mexico, Nevada and California. It's that hot sun on the black asphalt!

Even with the small D/A problems, I really have many wonderful memories of flying our beautiful "mountains" out West. More than I have logged in complaints of hampered performance. If anyone wants to experience the awsome creaqtion fly "WEST"!

Probably should mention a "Caution" with regard to that "second notch" of flaps recommendation in the manual.
We should keep in context exactly which manual we are reading and to which airplane the manual recommendation applies.
The "second notch" selection on original early 170B's would be too much for takeoff, as it would be approx. 30 degrees, because early B models only had zero/twenty/thirty/forty degree slection capability. They did not have a 10-degree positon like the later B models did. Later B's, and those early B's with later flap-position ratchets, might be able to use the "second notch", but not the early, unmodified ones. For this reason, I encourage everyone to refer to flap selections in terms of deflection angles or "degrees" rather than "notches".
(Takeoff performance is stated to be the same whether 10-degrees or 20-degrees of flaps are used on a B model. Gotta wonder tho', why they ever added the 10-degree selection if that were true.)