PLT381: Altimeter Setting Rules
What code PLT381 covers, why the FAA tests it, and how to study Altimeter Setting Rules before your checkride.
Recall regulations - altimeter settings
What this means for your checkride
The rules for altimeter settings: below 18,000 feet MSL, set the current reported setting of a station within 100 nautical miles, or the departure field's setting if none is available; at and above 18,000 feet (FL180), set the standard 29.92 inches of mercury. This keeps everyone's altitudes referenced consistently.
Consistent altimeter settings preserve vertical separation, so the FAA tests the regulatory setting procedures and the transition altitude.
Pilots keep a departure setting for a long cross-country. Below 18,000 feet you update to a station within 100 NM as you go; only in the flight levels does everyone share 29.92.
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.