The UK Ministry of Defence claims it is on track to deploy its Airborne Stand Off Radar (ASTOR) system operationally later this year. One of the Bombardier Sentinel R.Mk 1 aircraft that carries the new radar is being displayed at the Farnborough static park.

The Sentinel is a modified Bombardier Global Express business jet, equipped with a Raytheon Systems next-generation dual-mode Synthetic Aperture/Moving Target Indication (SAR/MTI) with an AESA antenna in a long ventral ‘canoe’ fairing.

The aircraft is flown by two pilots, with a mission crew nominally comprising a mission controller and two imagery analysts. This radar is based on the ASARS 2 radar used by the USAF’s U-2 reconnaissance aircraft. The five aircraft are augmented by eight dedicated mobile ground stations: six mounted on wheeled all terrain vehicles and two in air transportable containers.


One Sentinel R1 aircraft and a tactical ground station are currently participating in Empire Challenge - a major capability exercise at the US Navy’s China Lake test range in California, participating alongside other intelligence, surveillance and reconnaissance assets.

The Royal Air Force will accept its fifth and last Sentinel R1 airframe in the fourth quarter of this year, and No.5 Squadron at RAF Waddington expects to have four or five combat-ready crews available by year-end to support a deployment; potentially in support of coalition operations in Afghanistan. Currently the RAF has just two limited combat-ready air crews trained on the Sentinel.

“We are undergoing mission ‘wake-up’ right now, and are looking to introduce additional capabilities prior to delivery in the fourth quarter,” says Raytheon ASTOR programme manager Scott Tilden.

In anticipation of the system’s operational debut, the MoD is currently funding a number of upgrades to the Sentinel airframe. These include unspecified defensive aids system enhancements and additional security for the aircraft’s internal radio frequency communications equipment, says Wg Cdr Jerry Cowell, requirements manager for the UK Defence Equipment and Support organisation’s ASTOR integrated project team.

“There is still an aspiration to deploy at the end of this year, and we are on track to do that,” says Cowell. So-called capability assurance missions were completed in late April, following two successful flights in the US and four operationally-representative mission scenarios flown from RAF Waddington in Lincolnshire, he says.

When the ASTOR contract was signed in 1999, ASTOR was expected to have an in-service date during 2004. The first ground station vehicle was delivered in October 2002, and the first Sentinel aircraft made its maiden flight in May 2004, being delivered to the RAF in June 2007. Entry into service is now scheduled for October 2008 with an Initial Operating Capability (IOC) in October 2009.

The programme has suffered a succession of problems, with weight growth leading to the abandonment of an air-to-air refuelling capability, and with reports of problems with the aircraft’s datalinks and communications systems.

Source: Flight International