The long-range business jet governments use to move senior people. Live C-37 and Gulfstream V positions.
The C-37 is a Gulfstream V or G550 in government service, and it is how senior American officials travel when a 757 is too much aircraft. The Air Force, Navy, Marine Corps and Coast Guard all operate them, carrying combatant commanders, cabinet officials and congressional delegations.
Its appeal is range. A C-37 can fly from Washington to almost anywhere in Europe or the Middle East without stopping, which for a schedule-driven passenger matters more than cabin size.
The GLF5 designator covers the civil Gulfstream V and G550 too, including many government aircraft outside the United States — Poland, Uganda, Israel and others fly the type in a head-of-state role.
The A is based on the Gulfstream V and the B on the later G550, with updated avionics and winglets. Both report as GLF5.
Combatant commanders, cabinet secretaries, congressional delegations and senior military officers. It is a working transport rather than a ceremonial one.
The GLF5 designator covers every Gulfstream V and G550, and a number of governments use the type to carry heads of state. Those aircraft are carried in the military feed this site reads.