08-01-1999 Ask Mike! Archive
How does hot weather affect my airplane's performance?

Mike,

Now that the weather is hot. What is the best way of determining how my plane will perform differently in hot humid weather?

Andy
 
 
Andy:
 
Most, if not all, aircraft built since the '70's have a section in the flight manual, owners handbook, owners manual, or such, that has performance charts.  These charts will give you the answers you need provided:  your aircraft is in factory new condition, and you are a very proficient pilot!
 
Chances are, it's not, therefore, you can do one of several things.

1.  Get out the polish and smooth that bird up!  Also, make sure all fairings are intact, and there isn't any additions, subtractions, or alterations to your airframe that would increase drag.  These might include lots more antennas, different windshield design, different type of propeller, lack of fairings in key locations, more fairings to assist in airflow, etc.  These all could have positive or negative effects on TO, climb, and landing performance.  Also, don't forget your weight and balance.
2.  Add an arbitrary safety factor, say 25%, to all book values.  I must say, this should NOT be the only method employed.
3.  Practice your proficiency!  In my flight training, we practiced density altitude take off & climb using reduced power.  I don't recall to what extent we did this, but grab your friendly flight instructor, go out one morning when it's not hot yet, and try this.  Make sure that you do it in a safe manner, and you get a full briefing first, so you know what to expect.

By making sure your equipment (1) and skills (3) are top-notch, you should be able to avoid any serious consequences.  Using a fudge-factor also (2), can help in being safe, but most importantly, know your aircraft's and your limitations.
 
Gear Green,
Mike