PLT124: Atmospheric Effects on Performance
What code PLT124 covers, why the FAA tests it, and how to study Atmospheric Effects on Performance before your checkride.
Recall aircraft performance - atmospheric effects
What this means for your checkride
Atmospheric conditions change what the airplane can do. High temperature, high field elevation, and high humidity all raise density altitude, so the wing, propeller, and engine behave as if flying higher; takeoff roll lengthens, climb weakens, and true airspeed rises for the same indicated airspeed.
Performance charts assume the atmosphere, so the FAA tests how temperature, pressure, and humidity change takeoff, climb, and cruise before you commit to a departure.
Humidity is easy to ignore, but moist air is less dense than dry air, so a hot, humid day degrades performance more than the temperature alone suggests.
Where to study it
A code on your test report is an area of deficiency. An authorized instructor must review it with you and endorse that review before you take the practical test, and the examiner may revisit it during the oral. Study it until you can explain it out loud, not just recognize the answer.