XPLM_API XPLMMenuID XPLMFindAircraftMenu(void);

This function returns the ID of the menu for the currently-loaded aircraft, used for showing aircraft-specific commands.

The aircraft menu is created by X-Plane at startup, but it remains hidden until it is populated via XPLMAppendMenuItem() or XPLMAppendMenuItemWithCommand().

Only plugins loaded with the user’s current aircraft are allowed to access the aircraft menu. For all other plugins, this will return NULL, and any attempts to add menu items to it will fail.