[Llarry]

The U.S. Navy's Strategic Communications Wing One has three squadrons. Two of them fly E-6B Mercury aircraft (B707 airframes) to communicate with the nation's nuclear deterrent forces. A third squadron, VQ-7 is tasked with training the aircrews. With no suitable E-6B or other B707 version available, VQ-7 uses a Boeing 737-800 freighter for aircrew training: an unusual case of a military unit flying an aircraft without a miliary designation. I think the explanation may be that the 737 is a leased aircraft, not actually government-owed.