PLT123: Indicated vs True Airspeed
What code PLT123 covers, why the FAA tests it, and how to study Indicated vs True Airspeed before your checkride.
Recall aircraft performance - airspeed
What this means for your checkride
The airspeeds a pilot uses are related but distinct: indicated airspeed is what the instrument reads, calibrated airspeed corrects it for installation and position error, and true airspeed corrects for air density. As you climb into thinner air, true airspeed rises above the indicated value.
Performance and navigation depend on using the right airspeed, so the FAA tests converting among indicated, calibrated, and true airspeed and knowing which one a chart or limitation refers to.
Indicated and true airspeed match only near sea level on a standard day. At altitude, true airspeed is meaningfully higher than what the instrument shows.
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.