NewsOn6.com

TULSA, Oklahoma -- Tulsa's near-perfect weather has proven to be irresistible again to the crew of a huge, specialized Air Force plane.

The plane is a military version of the Boeing 747 which the Air Force calls the E-4B Nightwatch.  Its crew flew it to Tulsa in order to practice landings and take-offs.

The Pentagon uses the plane as the National Airborne Operations Center or NAOC.  In a national emergency, it would be used by the president, secretary of defense and/or the Joint Chiefs of Staff.

It's an effective tool for such situations because it would be hard for an enemy to locate.  Since it is a national security asset, the Air Force does not release any information about its operational activity, including a schedule of its training flights.

Some people have mistaken it for Air Force One.  While the airplanes used as Air Force One are also 747s, their paint schemes are much different -- including a large amount of blue -- and they don't have the signature hump behind the cockpit that the E-4B has.

The last time it came to Tulsa to practice landings and takeoffs was in October of 2010.

It also came to Tulsa in December of 2008, as NewsOn6.com reported then:

The E-4B's were first deployed in 1974, when they were known as the National Emergency Airborne Command Post or NEACP, which was pronounced "Kneecap".

In 1994, NEACP's name was changed to NAOC and the aircraft took on another responsibility: carrying FEMA crews to the sites of natural disasters where it serves as a temporary command post on the ground until more permanent facilities can be set up.

A division of the Air Force called Air Combat Command provides the maintenance and flight crews, but the planes' operations are coordinated by Strategic Command, which in turn answers to the Joint Chiefs of Staff. Strategic Command coordinates all of the Pentagon's strategic assets, regardless of whatever branch of service they serve.

In addition to the aircraft's status as an important national security asset, that command structure can make it a challenge to get details about its operation, including Thursday morning's training session in Tulsa.

We do know the E-4B's are flown by the 1st Airborne Command and Control Squadron from the 55th Wing at Offutt Air Force Base in Omaha, Nebraska. The Squadron has a total of four. The airplanes used to be kept at Andrews Air Force Base in Maryland, but were moved to the Midwest so they'd be safer from attack.

One E-4B and its crew stays on full alert at all times. One stays relatively close to Air Force One so that the President can access it quickly from anywhere in the world.