November 15, 2011:
After three years in service, the air force given new designations (E-11A and EQ-4B) to a manned aircraft and a UAV that have been operating as communications satellite substitutes. For the last three years the U.S. Air Force has been using business jets (the 44 ton BD 700) and specially equipped RQ-4B Global Hawk UAVs to act as communications relay stations over Afghanistan. The BD 700 is now the E-11A while the Global Hawk variant is now the EQ-4B.
Both carry BACN (Battlefield Airborne Communications Node) equipment. This allows ground troops to not only talk to others farther away (anywhere, in fact), but also enables ground troops to quickly connect with warplanes overhead. This is done with software that automatically transfers the data between the normally incompatible radio equipment. BACN also provides communications between aircraft.
The E-11A can stay in the air for over ten hours per sortie, while the EQ-4B can do more than twice that. Both fly at 12,900 meters (40,000 feet). The E-11A entered service first, followed about a year later by the EQ-4B. Currently there are three E-11As and two EQ-4Bs in service over Afghanistan.
Over the last three years BACN equipped aircraft have spent over 25,000 hours in the air. The E-11A is used when you have to get some BACN capability somewhere fast. The EQ-4B is for when you want to keep the BACN capability going someplace 24/7.
BACN is not a new idea for the air force. Eight years ago, realizing that every aerial battlefield in the past few decades has featured several KC-135 tankers circling, waiting to refuel a thirsty warplane, the U.S. Air Force gave the tankers an additional job. By adding a few hundred kilograms (220 pounds) of electronics mounted on a cargo pallet, which KC-135s are equipped to handle, the tanker was turned into a node in an aerial communications network. This solved the problem of how to connect warplanes to the new battlefield Internet when those planes do not have satellite communications capability. The aircraft use line-of-sight communications, which cannot connect with any ground station or aircraft that is over the horizon or behind a mountain. The system, called ROBE (Roll-On Beyond-line-of-sight Enhancement), was particularly useful in a mountainous area like Afghanistan. After the first 20 ROBE units, costing about $900,000 each, entered service, an upgraded model was introduced three years ago. The Department of Defense and NATO have already developed standards (LINK 16) for the transfer of video, picture and data electronically between ground stations, aircraft and ships using radio or satellite communications networks. KC-135s can't use BACN because they normally fly lower, at about 6,700 meters (20,000 feet).