TULSA, Oklahoma - A large U.S. Navy jet came to Tulsa for a little practice on Wednesday.

It's called an E-6B Mercury. Its crew spent the lunch hour practicing takeoffs and landings at TIA. 

The Navy has two squadrons of the jets at Tinker Air Force Base. When they were first assigned, their sole mission was to act as a flying relay station for commanders to communicate with ballistic missile submarines. The jets were equipped with very long antennas which they would reel out in order to allow radio communications to reach the submarines without the subs having to surface.

The jets were derived from the Boeing 707 airliner. Beginning in 1997, the Navy began adding equipment to the airplanes so that they could also act as flying command posts and launch land-based ballistic missiles in the event that ground-based control became impossible.

That mission is called "Looking Glass," which is shared by four Boeing 747 Nightwatch aircraft from Offutt Air Force Base in Nebraska. Those jets also come to Tulsa for the same reason: so their flight crews can practice takeoffs and landings.

The Navy has 16 Mercury jets. They're based at Tinker because its location in the middle of the continent gives the jets the ability to get to an ocean relatively quickly.