On July 3, 1988, 10:54 a.m., the USS Vincennes, a United States Navy missile cruiser, shot down an Iran Air civilian air liner killing all 290 passengers. The Vincennes, an Aegis cruiser, was the most sophisticated ship in the world. How could this tragedy happen?
The Iranian airbus was detected at 10:47 a.m. after a flurry of activity as Iranian and American forces clashed. At 10:10 a.m. a U.S. chopper had been fired upon by Iranian gunboats, which were near two neutral merchant ships. The helicopter returned to the Vincennes. At 10:42 the Vincennes and the frigate USS Elmer Montgomery fired on the Iranian gunships after they turned towards the Vincennes from the direction of Bandar Abbas. The radar on the USS Vincennes detected the Iranian airliner as a hostile aircraft. The most sophisticated technology mistook the Airbus (length:175 feet, 11 inches) for an F-14 (length: 62 feet, 8 inches). The Vincennes also miscalculated the altitude of the plane by 3,000 feet and showed it to be descending when it was climbing.
The Aegis system accounts for nearly half of the ship's $1.2 billion dollar cost. Its radar is supposed to Simultaneously track hundreds of objects flying within 200 miles of the ship. However, the downing of the Airbus showed that the Aegis cannot distinguish between different types of planes from their radar images. Its electronic system is built to recognize the radar emissions of nearby aircraft, but perhaps the pilot of the airbus did not bother to turn the radar on for the short flight from Bandar Abbas to Dubai.
Radar can only determine an aircraft's altitude, bearing and speed, so the warship commander relies on an electronic device called a transponder, to identify commercial aircraft. The transponder is triggered by an interrogating surface-based radar and automatically transmits encoded radio data about the plane. This information includes the code number of the plane, its airline, and rate of ascent and descent. In the case of friendly military aircraft, a similar device sends an identifying password to the interrogating radar. In the case of the Iranian Airbus, two 1FF signals were received and it was not clear which was correct. One of the signals was civilian, the other was previously identified with F-14s. The Vincennes, fearing that it was being attacked, had to take immediate action and shot the airliner out of the sky.
Reliance on sophisticated hardware like the Aegis radar system is an invitation for disaster. During tests of this system in April 1983 it detected and destroyed only four out of sixteen decoys and, montlis later, only three out of six targets. Even through the system was proven ineffective, the construction of the ship proceeded. The Aegis system may actually even put the ship at a disadvantage because the system emits four megawatts of energy the moment it is activated. This enormous output of energy makes the ship a powerful electronic beacon and an easy target for the radar-homing missiles the Soviets sensibly developed
The 270 deaths of Iranian civilians is an instructive reminder: Sophisticated offensive technology is not a panacea for avoiding tragic miscalculations. It may very well be the cause.