The Sentinel R1 jet would work alongside the existing Nimrod fleet
"Spy planes" that could help combat roadside bombs from seven-and-a-half miles above the ground have just entered squadron service after successful trials in Afghanistan. How effective would they be in fighting the Taleban and saving lives?
At almost £1bn for five, the Sentinel R1 jet does not come cheap, but the Ministry of Defence (MoD) hopes its latest "eye in the sky" will have a real impact.
The twin-engined plane carries some of the world's most sophisticated radar equipment, allowing it to detect and track enemy movement over huge areas.
The Army hopes the Royal Air Force jets will provide a clearer picture of insurgents' positions as well as pinpoint fixed targets.
The number of UK troops killed on operations in Afghanistan since 2001 stands at 143.
The Airborne Stand-Off Radar (Astor) can cover thousands of square miles, looking deep into valleys, picking out well-used enemy routes and mapping vehicle activity.
Radar creates detailed images comparable to images taken by satellites
Two Rolls-Royce Deutschland BR710 turbo fan engines
40,000ft maximum altitude
Crew of five can fly for nine hours without jet having to refuel
A thrust of 14,750lbs each with a 0.75Mach maximum speed
Contract awarded to Raytheon Systems in 1999
Source: Royal Air Force
Information is relayed to ground stations within seconds of the images being captured, allowing troops below to react at speed to tactical planning.
Intelligence Corps detachment commander, Major Will Tosh, told the BBC: "The system is unique in terms of its search capability, because it looks at such a large area.
"It can pick up a lot of data and see what's happening on the ground, saving time and effort. Commanders can see where activity is and what it is, and move forces into that area."
He said the planes could be used as a "tool" in the battle against insurgency, including roadside bomb attacks, but only in conjunction with other systems.
He added that because the plane flew so high it would be outside the engagement zone and away from the threat of surface-to-air missiles.
Mobile ground stations receive data covering thousands of miles
Sentinel R1s are operated by a crew of five - two pilots, two imagery analysts and a commander - and can fly for more than nine hours at a time.
The radar works by looking down to the ground while the aircraft flies in a straight line.
It transmits pulses and receives target information as it moves, building up a picture of the target area. Powerful computers and software then allow rapid processing of the information.
It is also compatible with joint coalition systems such as the US JStars radar programme.
Maj Tosh said the Sentinels would work alongside existing Nimrods to "complement" but not replace any of their functions.
"The Nimrod has a full motion video sensor, our system doesn't. We have a radar platform and can work day and night through bad weather, the Nimrod can't," he said.
The Sentinel was successfully tested in Afghanistan in November and December last year by 3 Commando Brigade.
The MoD has spent £954m on five aircraft plus eight ground stations to be operated by 5 (Army Co-operation) Squadron, based at RAF Waddington in Lincolnshire.
The system is introducing a new capability into the British arsenal
Maj Will Tosh
The fifth and final Sentinel R1 has just been delivered to the base.
Group Captain Harry Kemsley said: "This system is about answering the questions the customer on the ground needs answering - getting the information soldiers need to the soldiers.
"The ability to look beyond the range of the eye, binoculars and rifle sight is now available with our system. "
Peter Felstead, editor of Jane's Defence Weekly, agreed, saying it was a vital platform for surveillance which would bring "significant capability" to forces in the field.
Maj Tosh said he hoped the jets would be deployed in Afghanistan as quickly as possible so they could "do it for real".
"The system is introducing a new capability into the British arsenal that we don't currently have, it's cutting-edge technology which will only get better in the future," he said.
"The system is that flexible, it can fit into any scenario, and is not just contained by the current Afghan situation."
The RAF said Astor would become the most advanced long-range, airborne surveillance system of its kind in the world.
The Sentinel has been used for operations in Afghanistan
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