U.S.-Iran Missile Encounter: Pure Aerial Electronics

When an American F-14 Tomcat fighter launched two missiles at an Iranian jet last Saturday high over the Strait of Hormuz, the two planes played out a purely electronic encounter in a flash of high-technology combat that illustrated some of the capabilities and the limits of modern military aircraft.

Although the Administration has refused to confirm the incident publicly, a variety of anonymous officials have provided details of the encounter, which produced neither a winner nor a loser.

According to these officials, an Iranian jet believed to be an American-built F-4 Phantom of Vietnam War vintage approached a slower, propeller-driven Orion P-3 surveillance plane as the American aircraft was assisting the naval escort of three Kuwaiti tankers through the narrow strait that leads into the Persian Gulf.

Tracked by Cruiser

The Iranian jet’s approach was tracked by the Valley Forge, an Aegis-class cruiser accompanying the Kuwaiti tankers. The vessel carries the Navy’s most sophisticated air-defense system. When the Iranian pilot ignored repeated warnings radioed from the Valley Forge to change course, F-14s from the carrier Constellation, cruising in the Arabian Sea, sped toward the scene.

Much of what reportedly happened thereafter was influenced by the sophisticated radar on board the aircraft involved.

An indication that the Iranian plane had fixed its targeting radar on the American surveillance plane would have been considered proof of hostile intent. No such radar “lock” was confirmed, but under the hair-trigger rules of engagement in force in the gulf since the U.S. frigate Stark was hit with the loss of 37 lives, in an accidental attack by an Iraqi jet, the F-14 pilot was authorized to fire when the Iranian plane did not veer away, officials said.

The F-14 could take aim effectively, even though the target was not within sight, because of the capabilities of its own targeting radar.

Strong, Narrow Beam

Unlike a plane’s broad-beamed search radar, which sweeps a wide cone of sky in front of a fighter plane, targeting radar emits a strong, narrow beam of energy on a distinctive frequency band. It provides precise tracking data for air-to-air missiles. Once a pilot fixes the beam on a target, it “locks on” and with the aid of a computer continues to track the target plane, feeding data to the on-board missiles.

But the Iranian jet almost certainly carried a radar receiver tuned to the frequency band of the F-14’s radar. Like an automobile’s radar detector, it would sound an alarm in the cockpit, indicating in this case that an American fighter had lain an electronic pathway to the Iranian jet and was in position to launch its air-to-air missiles.

Another factor in the encounter was the missiles used--12-foot-long Sparrows that fly at more than three times the speed of sound to a maximum range of about 30 miles.

While it is hard to evade at closer ranges, the Sparrow has the disadvantage of relying on the F-14’s radar signal bouncing off the target plane. The F-14 must continue to fly toward its target, “illuminating” it with its powerful radar and providing an enemy pilot with a continuous electronic warning.

In contrast, the more sophisticated Phoenix air-to-air missiles that are carried by some Navy F-14 fighters have their own on-board radar that allows the attacking pilot to “fire and forget” the Phoenix, once it locks onto its target.

Pilot Had 45 Seconds

In this instance, the F-14 pilot launched his two Sparrow missiles from the outer edge of their maximum range, about 30 miles, leaving the Iranian pilot about 45 seconds in which to take evasive action before impact.

Aircraft are more maneuverable than the slender missiles with their small guidance fins, giving the target plane an advantage if its pilot has sufficient time to react.

The Iranian pilot is said to have banked sharply, probably diving to low altitude to lose himself in the “clutter” of radar reflections from the surface waters of the gulf and vanished from radar screens.

There were no electronic indications that the Sparrows struck home, and Iran has claimed no damage. The entire encounter was over in seconds.

The Iranian plane, if it was in fact a McDonnell-Douglas Phantom, was aptly named. It was visible only as a blip on radar screens. Human eyes never saw it.