--- a/aircraft_cmd.c	Mon Jun 05 18:16:41 2006 +0000
+++ b/aircraft_cmd.c	Wed Jun 07 07:20:28 2006 +0000
@@ -21,6 +21,7 @@
 #include "vehicle_gui.h"
 #include "table/sprites.h"
 #include "newgrf_engine.h"
+#include "newgrf_callbacks.h"
 
 static bool AirportMove(Vehicle *v, const AirportFTAClass *Airport);
 static bool AirportSetBlocks(Vehicle *v, AirportFTA *current_pos, const AirportFTAClass *Airport);
@@ -156,6 +157,34 @@
 }
 
 
+/**
+ * Calculates cargo capacity based on an aircraft's passenger
+ * and mail capacities.
+ * @param cid Which cargo type to calculate a capacity for.
+ * @param engine Which engine to find a cargo capacity for.
+ * @return New cargo capacity value.
+ */
+static uint16 AircraftDefaultCargoCapacity(CargoID cid, EngineID engine_type)
+{
+	const AircraftVehicleInfo *avi = AircraftVehInfo(engine_type);
+
+	assert(cid != CT_INVALID);
+
+	/* An aircraft can carry twice as much goods as normal cargo,
+	 * and four times as many passengers. */
+	switch (cid) {
+		case CT_PASSENGERS:
+			return avi->passenger_capacity;
+		case CT_MAIL:
+			return avi->passenger_capacity + avi->mail_capacity;
+		case CT_GOODS:
+			return (avi->passenger_capacity + avi->mail_capacity) / 2;
+		default:
+			return (avi->passenger_capacity + avi->mail_capacity) / 4;
+	}
+}
+
+
 /** Build an aircraft.
  * @param tile tile of depot where aircraft is built
  * @param p1 aircraft type being built (engine)
@@ -192,6 +221,7 @@
 		return_cmd_error(STR_00E1_TOO_MANY_VEHICLES_IN_GAME);
 
 	if (flags & DC_EXEC) {
+		CargoID cargo;
 		uint x;
 		uint y;
 
@@ -256,6 +286,32 @@
 
 		u->subtype = 4;
 
+		/* Danger, Will Robinson!
+		 * If the aircraft is refittable, but cannot be refitted to
+		 * passengers, we select the cargo type from the refit mask.
+		 * This is a fairly nasty hack to get around the fact that TTD
+		 * has no default cargo type specifier for planes... */
+		cargo = FindFirstRefittableCargo(p1);
+		if (cargo != CT_INVALID && cargo != CT_PASSENGERS) {
+			uint16 callback = CALLBACK_FAILED;
+
+			v->cargo_type = cargo;
+
+			if (HASBIT(EngInfo(p1)->callbackmask, CBM_REFIT_CAPACITY)) {
+				callback = GetVehicleCallback(CBID_VEHICLE_REFIT_CAPACITY, 0, 0, v->engine_type, v);
+			}
+
+			if (callback == CALLBACK_FAILED) {
+				/* Callback failed, or not executed; use the default cargo capacity */
+				v->cargo_cap = AircraftDefaultCargoCapacity(v->cargo_type, v->engine_type);
+			} else {
+				v->cargo_cap = callback;
+			}
+
+			/* Set the 'second compartent' capacity to none */
+			u->cargo_cap = 0;
+		}
+
 		e = GetEngine(p1);
 		v->reliability = e->reliability;
 		v->reliability_spd_dec = e->reliability_spd_dec;

--- a/vehicle.c	Mon Jun 05 18:16:41 2006 +0000
+++ b/vehicle.c	Wed Jun 07 07:20:28 2006 +0000
@@ -692,6 +692,25 @@
 	return HASBIT(EngInfo(engine_type)->refit_mask, cid);
 }
 
+/** Find the first cargo type that an engine can be refitted to.
+ * @param engine Which engine to find cargo for.
+ * @return A climate dependent cargo type. CT_INVALID is returned if not refittable.
+ */
+CargoID FindFirstRefittableCargo(EngineID engine_type)
+{
+	CargoID cid;
+	uint32 refit_mask = EngInfo(engine_type)->refit_mask;
+
+	if (refit_mask != 0) {
+		for (cid = CT_PASSENGERS; cid < NUM_CARGO; cid++) {
+			if (HASBIT(refit_mask, _global_cargo_id[_opt_ptr->landscape][cid])) return cid;
+		}
+	}
+
+	return CT_INVALID;
+}
+
+
 static void DoDrawVehicle(const Vehicle *v)
 {
 	uint32 image = v->cur_image;

--- a/vehicle.h	Mon Jun 05 18:16:41 2006 +0000
+++ b/vehicle.h	Wed Jun 07 07:20:28 2006 +0000
@@ -267,6 +267,7 @@
 
 bool CanFillVehicle(Vehicle *v);
 bool CanRefitTo(EngineID engine_type, CargoID cid_to);
+CargoID FindFirstRefittableCargo(EngineID engine_type);
 
 void ViewportAddVehicles(DrawPixelInfo *dpi);