diff --git a/airport.h b/airport.h
index f36923fea6..8a9d4b60bb 100644
--- a/airport.h
+++ b/airport.h
@@ -10,40 +10,40 @@ enum {MAX_HELIPADS  = 2};
 
 // Airport types
 enum {
-	AT_SMALL = 0,
-	AT_LARGE = 1,
-	AT_HELIPORT = 2,
-	AT_METROPOLITAN = 3,
+	AT_SMALL         = 0,
+	AT_LARGE         = 1,
+	AT_HELIPORT      = 2,
+	AT_METROPOLITAN  = 3,
 	AT_INTERNATIONAL = 4,
-	AT_OILRIG = 15
+	AT_OILRIG        = 15,
 };
 
 // do not change unless you change v->subtype too. This aligns perfectly with its current setting
 enum {
-	AIRCRAFT_ONLY = 0,
-	ALL = 1,
-	HELICOPTERS_ONLY = 2
+	AIRCRAFT_ONLY    = 0,
+	ALL              = 1,
+	HELICOPTERS_ONLY = 2,
 };
 
 // Finite sTate mAchine --> FTA
 typedef struct AirportFTAClass {
-	byte nofelements;							// number of positions the airport consists of
+	byte nofelements;                     // number of positions the airport consists of
 	const byte *terminals;
 	const byte *helipads;
-	byte entry_point;							// when an airplane arrives at this airport, enter it at position entry_point
-	byte acc_planes;							// accept airplanes or helicopters or both
-	const TileIndexDiffC *airport_depots;	// gives the position of the depots on the airports
-	byte nof_depots;							// number of depots this airport has
-	struct AirportFTA *layout;		// state machine for airport
+	byte entry_point;                     // when an airplane arrives at this airport, enter it at position entry_point
+	byte acc_planes;                      // accept airplanes or helicopters or both
+	const TileIndexDiffC *airport_depots; // gives the position of the depots on the airports
+	byte nof_depots;                      // number of depots this airport has
+	struct AirportFTA *layout;            // state machine for airport
 } AirportFTAClass;
 
 // internal structure used in openttd - Finite sTate mAchine --> FTA
 typedef struct AirportFTA {
-	byte position;										// the position that an airplane is at
-	byte next_position;								// next position from this position
-	uint32 block;	// 32 bit blocks (st->airport_flags), should be enough for the most complex airports
-	byte heading;	// heading (current orders), guiding an airplane to its target on an airport
-	struct AirportFTA *next_in_chain;	// possible extra movement choices from this position
+	byte position;                    // the position that an airplane is at
+	byte next_position;               // next position from this position
+	uint32 block;                     // 32 bit blocks (st->airport_flags), should be enough for the most complex airports
+	byte heading;                     // heading (current orders), guiding an airplane to its target on an airport
+	struct AirportFTA *next_in_chain; // possible extra movement choices from this position
 } AirportFTA;
 
 void InitializeAirports(void);