PLT139: Aircraft Warning Systems
What code PLT139 covers, why the FAA tests it, and how to study Aircraft Warning Systems before your checkride.
Recall aircraft warning systems - stall / fire / retractable gear / terrain awareness
What this means for your checkride
These are the safety warning systems that alert the pilot to a developing problem: the stall warning that sounds as the wing approaches the critical angle of attack, a fire warning, a gear warning that the landing gear is not down when it should be, and terrain awareness systems that warn of rising ground.
Warning systems give the margin to react before a problem becomes an accident, so the FAA tests what each system senses and the correct response to its alert.
Pilots silence a warning instead of acting on it. A gear or terrain warning is telling you to change the flight path or configuration now; treating it as a nuisance to cancel is how the warned-about event actually happens.
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.