MD-11
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Confusion; Situational Awareness
Aircraft Equipment Problem Less Severe
Flight Crew Inflight Shutdown
Aircraft
Loss of #3 Engine Oil QTY at about 2 hours into flight. Followed QRH (Quick Reference Handbook); good oil pressure and temperature. Per [Maintenance Control] request we pulled the engine to idle for 2 minutes but no change. Oil not 'hiding.' About 2 1/2 hours we saw a constant decrease in oil pressure. QRH said to keep engine running until oil pressure or temperature abnormal. WHAT DEFINES ABNORMAL IN THIS CASE? I asked [Maintenance Control] and [Dispatch] how long to keep it running or what is abnormal. I decided to shut it down while pressure was still in the green (100 psi) knowing when we went to idle it would go amber or red. Performed engine shutdown with QRH. Manual landing due to radio altimeter inoperative.
MD-11 Captain reported loss of engine oil quantity in #3 engine while in-flight.