On Sunday, two RAF air crew became the first victims of friendly fire in the war when their Tornado GR4 was blown apart over Kuwait by a Patriot battery.The US Central Command in Qatar confirmed similarities between the Tornado incident and that involving the F-16, which attacked after the Patriot battery locked its radar on the plane.Attention was focusing on the Identification Friend or Foe (IFF) boxes carried by all British and American aircraft, which send a unique encoded signal designed to warn Allied forces of their presence. Lt Mark Kitchens, a US military spokesman, said: “There is an investigation to identify procedural changes to ensure the safety of our air crews and Patriot crews in combat.”Friendly fire has become a real hazard in modern warfare. In the 1991 Gulf War nine British soldiers were killed when their two armoured personnel carriers came under fire from an A-10 “tankbuster” aircraft. The death toll was the highest in a single incident during the war.From the Second World War to Vietnam, friendly fire accounted for 1.5 to 2.8 per cent of casualties. In Operation Desert Storm in 1991, the figure rose to 17.4 per cent, killing or injuring 107 American and 22 British troops.

Of those, 75 per cent of incidents were in ground-to-ground engagement.”The graph [on casualties from friendly fire] is going the wrong way … it’s going up,” Lt-Gen James T Conway, commanding 1st Marine Expeditionary Force, said before the war started. All aircraft, anti-aircraft and naval systems have IFF built in to their navigation systems: when an aircraft or vessel comes into their radar field, these transmit a series of encrypted queries in radio bursts lasting a few microseconds. Only “friendly” combatants’ systems have computers programmed with the mathematical codes to solve the questions and radio their reply.

The reply, or lack of it, is detected almost instantaneously.But it can go wrong when codes have not been shared. A friendly aircraft straying into an adjacent area of conflict without the correct codes could look like an enemy to ground-based systems Tanks do not generally use IFF. Jane’s Defence Weekly news editor, Ian Kemp, said yesterday: “Aircraft have always been fitted with these things and now they are trying to install a similar system on ground vehicles. The US is leading the way in this research and we, no doubt, will follow.”He said that friendly fire has always been a factor in modern warfare. Electrical failure in aircraft could also account for casualties, he said. “It is a particular danger of modern operations when you get a fast battle. In a fast-moving battle it can be quite awkward, particularly at night and in poor visibility, to distinguish one from the other.”Challenger ii backbone of the British assaultChallenger II, the British Army’s main battle tank, is a new development but not without its problems.Around 150 improvements have been made over its predecessor, the Challenger I, which saw action in the1991 Gulf War.