Saving Sentinel

October 22, 2011: STRATEGY PAGE

Britain's RAF (Royal Air Force) is faced with major budget cuts over the next five years. One of the systems selected for deactivation, the new Sentinel R1 ASTOR (Airborne Stand-Off Radar), is now collecting many fervent RAF and army fans calling for this aircraft to remain in service. That's because of how successful Sentinel has been in Afghanistan. Britain recognizes this, and plans to retire Sentinel only after 2015, when British ground troops are scheduled to be withdrawn from Afghanistan. The RAF has been told they could more inexpensively replicate Sentinel functions in a UAV. But with all these cuts, the RAF does not see getting enough money to develop a UAV Sentinel replacement. It cost $1.5 billion to develop Sentinel and build five of them and army commanders believe they would be invaluable in any future operations.

It was only three years ago, after a decade of development, that Sentinel aircraft were sent to Afghanistan. Sentinel is similar to the three decade old U.S. E-8 JSTARS. But instead of mounting the radar and computers in a four engine jet transport (the 707), the British used a 44 ton Canadian Bombadier Global Express twin engine business jet. The highly automated Sentinel has two pilots, and three people in the back running the surveillance equipment. Sentinel operates at about 15,000 meters (45-50,000 feet) and can track vehicles, or even people, on the ground up to 160 kilometers away. Large vehicles (like missile transporters/launchers) can be tracked at twice that range. Sorties in Afghanistan average about nine hours, although the aircraft is capable of staying in the air for 14 hours. The U.S. has been using its E-8 ground radar aircraft in Iraq and Afghanistan with great success.

Sentinel uses a U.S. made Raytheon ASARS-2 radar. This is a Synthetic Aperture Radar (SAR) system that can focus on a smaller area and provide photo quality images. Sentinel also has a large array of electronic warfare equipment and counter-missile systems. But in Afghanistan it mainly uses its radar, and its satellite and ground communications links to send images to the troops below, who can then run down known or suspected hostiles.

In Afghanistan, Sentinel has also been used for intelligence work (to determine normal traffic patterns in an area, and to alert combat commanders when abnormal traffic shows up), and to track enemy vehicles. The Taliban typically move around in trucks and SUVs, and sometimes on motorcycles. All can be tracked by Sentinel, in any weather. Since Sentinel operates at high altitudes, it is out-of-sight and silent to the Taliban below, who never know when they are being tracked.