U.S. Air Force C-5M Galaxy cargo aircraft, registration 86-0020, that was forced to perform a nose gear up landing at the Spanish airbase after experiencing an unknown failure that made it unable to extend its nose landing gear.According to a source who wishes to remain anonymous, while on approach into Rota, as well extending the gear, the nose gear showed a “red wheels” indication. This told the crew that the gear doors were open but the gear didn’t move.