I was in the Navy for 12-yrs and spent 3-1/2-yrs on “Dodge” (Diego Garcia). Two tours, one in the mid-80’s and another in the early-90’s. It was the best place on earth I have ever lived; it was, and is, a true tropical paradise.
It is also very strategic and unknown to most. That era was pre-email and pre-internet; much has changed I am sure. But an airfield and air operations haven’t changed that much, at least as far as arrivals and departures go. If M370 did go to DG, then it likely arrived after dark would not have attracted much attention; planes arrive and depart at all hours on most military bases.
At minimum, air traffic control, refueling and British Customs personnel would have been involved. The plane likely landed, taxied to the most remote ramp area and was serviced and prepared for the next leg of the journey. This could have been done in a relatively short period of time.
The longer the plane was on the ground, the more conspicuous the 777 was parked and/or the more personnel/units involved in processing the aircraft would have greatly increased word getting out about its presence.
Who was on duty in the tower, communicating with the plane? What was the plane ID (transponder)? Who ordered the fuel? Who delivered the fuel? Were Brits informed at all? Was support equipment needed (e.g., air conditioning cart, generator cart)? Were body bags brought on board? Were exterior markings changed on the aircraft?
Who was on duty that day? Were personnel planted and scheduled instead of regulars? In my time, special personnel would have stuck out like a sore thumb, as the number of enlisted personnel was fairly small in both the Air Force and Navy units. Maybe civilians have taken over those duties; it is all speculation.
All in all, I think it was possible for a civilian airliner to zip into and out of Diego Garcia under cover of night, but it would have required advanced planning and a real good story to go along with it.
