Expert: Colin Woehrle - 6/18/2008

Question
Colin;
Quick flight question for you...assume a Cessna 172.  Is it fair to say that once you trim the aircraft to a pitch attitude that will give you say, 70 kts...the airplane will respond to changes in power by raising or lowering the nose to maintain 70kts?
If so, is it a reasonable strategy for a stabilized landing approach to get the plane trimmed for a desired speed and then control descent rate with power - and let the nose of the plane move up or down to stay at the trimmed speed?
I've tried this in Flight Simulator X and that is how the aircraft responds...does it work like that in reality?
Thanks;

Answer
Hi Matt,

Partly true. If you trim the aircraft to a pitch that will maintain 70kts at a certain power setting, any change to power will change the pitch attitude. It will not necessarily maintain 70kts though. Let's say that it took 2000rpm to maintain 70kts on a standard day (temperature and atmospheric pressure) and you push in full power. The aircraft will pitch up, lose airspeed and eventually stall.

As far as the approach goes, it's good practice to get the aircraft trimmed out for your approach speed and then make minor adjustments to power for altitude changes and minor pitch adjustments for airspeed changes.

Hope this helps!

Colin