diff -r 99324280e2ad -r 6f20de9e4f1b src/openttd.cpp
--- a/src/openttd.cpp	Fri Mar 02 11:36:34 2007 +0000
+++ b/src/openttd.cpp	Fri Mar 02 12:01:24 2007 +0000
@@ -40,6 +40,7 @@
 #include "fileio.h"
 #include "hal.h"
 #include "airport.h"
+#include "aircraft.h"
 #include "console.h"
 #include "screenshot.h"
 #include "network/network.h"
@@ -1818,6 +1819,20 @@
 		}
 	}
 
+	if (CheckSavegameVersion(50)) {
+		Vehicle *v;
+		/* Aircraft units changed from 8 mph to 1 km/h */
+		FOR_ALL_VEHICLES(v) {
+			if (v->type == VEH_Aircraft && v->subtype <= AIR_AIRCRAFT) {
+				const AircraftVehicleInfo *avi = AircraftVehInfo(v->engine_type);
+				v->cur_speed *= 129;
+				v->cur_speed /= 10;
+				v->max_speed = avi->max_speed;
+				v->acceleration = avi->acceleration;
+			}
+		}
+	}
+
 	if (CheckSavegameVersion(49)) FOR_ALL_PLAYERS(p) p->face = ConvertFromOldPlayerFace(p->face);
 
 	return true;