How HMS Sheffield was sunk before Britain could activate Falklands war missile ‘kill switch’
An Exocet headed for the frigate HMS Ambuscade was knocked off course with the use of chaff, strips of aluminum exactly half the length of the wavelength of enemy radar, that would present an alternative target for the missile but which would not cause it to detonate.
An Exocet intended for Ambuscade flew past it, but then locked onto another ship, the poorly-defended merchant vessel Atlantic Conveyor, which was hit, caught fire and went down over the course of three days.
Twelve sailors were killed and 10 helicopters were lost, meaning that the Army did not have troop-carrying Chinook helicopters that were intended to transport them across the Falklands, rather than having to march across on foot.
Other ships were defended against Exocets with a covering of radar-absorbing material, whilst others used a decoy box to draw the missiles away.
Similar in size to a tea chest, with sharp edges and a similar radar signature to a warship, the decoy was dangled from a helicopter slightly above the missile’s maximum altitude, so that it targeted the decoy but flew harmlessly underneath it.
British experts had discovered that Exocets scanned the horizon from left to right, meaning that they could be drawn away if a decoy was flown to the left of a ship.
Changing tactics to prevent disaster
The British also worked out a new tactic unique to the Exocet: rather than turning side-on to the threat so that a missile would travel the shortest distance through the ship and cause the least damage (the best tactic against heavy “dumb bombs”) , the ships would face the missile end-on, presenting the smallest possible radar cross-section to a lightweight missile that would explode on impact.
On June 12, the destroyer HMS Glamorgan was attacked by an Exocet fired from the shore about 20 miles away.
With little time to react, the ship’s captain ordered a high-speed turn away from the missile, avoiding a side-on impact. Instead, the missile hit the deck of the ship, made a large hole in the hangar deck and hit a fueled and armed Wessex helicopter, killing 14 sailors.
The ship was not lost, however, and remained battleworthy, although Argentina surrendered two days later.
Now 40 years on, Mitterrand, Thatcher and many of the key players in the conflict have passed away, but the questions they left behind them still demand answers.