Function XPLMFindFirstNavAidOfType 

pub unsafe extern "C" fn XPLMFindFirstNavAidOfType(
    inType: XPLMNavType,
) -> XPLMNavRef

XPLMFindFirstNavAidOfType

This routine returns the ref of the first navaid of the given type in the database or XPLM_NAV_NOT_FOUND if there are no navaids of that type in the database. You must pass exactly one navaid type to this routine.