diff --git a/src/airport.h b/src/airport.h
--- a/src/airport.h
+++ b/src/airport.h
@@ -180,7 +180,7 @@ DECLARE_ENUM_AS_BIT_SET(AirportFTAClass:
 /** Internal structure used in openttd - Finite sTate mAchine --> FTA */
 struct AirportFTA {
 	AirportFTA *next;        ///< possible extra movement choices from this position
-	uint64 block;            ///< 64 bit blocks (st->airport_flags), should be enough for the most complex airports
+	uint64 block;            ///< 64 bit blocks (st->airport.flags), should be enough for the most complex airports
 	byte position;           ///< the position that an airplane is at
 	byte next_position;      ///< next position from this position
 	byte heading;            ///< heading (current orders), guiding an airplane to its target on an airport