Index: src/aircraft_cmd.cpp
===================================================================
--- src/aircraft_cmd.cpp	(revision 17745)
+++ src/aircraft_cmd.cpp	(working copy)
@@ -1117,10 +1117,17 @@
 		uint z = v->z_pos;
 
 		if (amd->flag & AMED_TAKEOFF) {
-			z = min(z + 2, GetAircraftFlyingAltitude(v));
+			z = min(z + 3, GetAircraftFlyingAltitude(v));
 		}
 
-		if ((amd->flag & AMED_HOLD) && (z > 150)) z--;
+		if (amd->flag & AMED_HOLD) {
+			uint curz = GetSlopeZ(x, y) + 130; // max tile height is 120 and max plane altitude is 255, so we stay below
+			if (z > curz) {
+				z--;
+			} else if (z < curz) {
+				z++;
+			}
+		}
 
 		if (amd->flag & AMED_LAND) {
 			if (st->airport_tile == INVALID_TILE) {