diff --git a/ArduPlane/Plane.h b/ArduPlane/Plane.h
index 23b26ec42c..0866ab3d2d 100644
--- a/ArduPlane/Plane.h
+++ b/ArduPlane/Plane.h
@@ -798,6 +798,7 @@ private:
     bool terrain_disabled();
 #if AP_TERRAIN_AVAILABLE
     bool terrain_enabled_in_current_mode() const;
+    bool terrain_enabled_in_mode(Mode::Number num) const;
     enum class terrain_bitmask {
         ALL             = 1U << 0,
         FLY_BY_WIRE_B   = 1U << 1,
diff --git a/ArduPlane/altitude.cpp b/ArduPlane/altitude.cpp
index 6b2e9f0379..6fec0063e8 100644
--- a/ArduPlane/altitude.cpp
+++ b/ArduPlane/altitude.cpp
@@ -765,6 +765,11 @@ const Plane::TerrainLookupTable Plane::Terrain_lookup[] = {
 };
 
 bool Plane::terrain_enabled_in_current_mode() const
+{
+    return terrain_enabled_in_mode(control_mode->mode_number());
+}
+
+bool Plane::terrain_enabled_in_mode(Mode::Number num) const
 {
     // Global enable
     if ((g.terrain_follow.get() & int32_t(terrain_bitmask::ALL)) != 0) {
@@ -773,7 +778,7 @@ bool Plane::terrain_enabled_in_current_mode() const
 
     // Specific enable
     for (const struct TerrainLookupTable entry : Terrain_lookup) {
-        if (entry.mode_num == control_mode->mode_number()) {
+        if (entry.mode_num == num) {
             if ((g.terrain_follow.get() & int32_t(entry.bitmask)) != 0) {
                 return true;
             }