PLT127: Aircraft Performance
What code PLT127 covers, why the FAA tests it, and how to study Aircraft Performance before your checkride.
Recall aircraft performance - density altitude
What this means for your checkride
Density altitude is the altitude the air feels like to the airplane after correcting pressure altitude for temperature. High density altitude, from heat, high elevation, or humidity, thins the air so the wing makes less lift, the propeller less thrust, and the engine less power, all of which lengthen the takeoff and flatten the climb.
Density altitude is the single biggest performance factor a pilot manages, so the FAA tests whether you can recognize the conditions that raise it and predict the loss of performance before you take off.
Pilots plan by the temperature they took off in last week. Density altitude changes hour to hour with temperature, so a runway that worked in the cool morning can be marginal by afternoon at the same field.
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.