Editing

**Altitude reference frames — memorize both.** - **AGL — Above Ground Level.** Height above the terrain directly below. Used for Part 107's 400 ft ceiling and most airspace ceilings of Class C, D, E (700/1200 AGL). - **MSL — Mean Sea Level.** Absolute elevation above the ocean. Used for Class A (FL 180 MSL – FL 600 MSL) and many sectional-chart ceiling callouts. - **Pilot trap:** the same "100 ft" means very different things depending on which frame. If a sectional ceiling says "70" without parentheses, it's **MSL** (add 00 → 7 000 ft MSL). If it's in parentheses like "(12)" it's **AGL**.

Cancel