diff --git a/ArduPlane/altitude.pde b/ArduPlane/altitude.pde
index cd46561504..b6c504e52a 100644
--- a/ArduPlane/altitude.pde
+++ b/ArduPlane/altitude.pde
@@ -87,7 +87,7 @@ static void setup_glide_slope(void)
         // is basically to prevent situations where we try to slowly
         // gain height at low altitudes, potentially hitting
         // obstacles.
-        if (relative_altitude() > 20 || above_location_current(next_WP_loc)) {
+        if (adjusted_relative_altitude_cm() > 2000 || above_location_current(next_WP_loc)) {
             set_offset_altitude_location(next_WP_loc);
         } else {
             reset_offset_altitude();