Korean Air Lines 007, 1 September 1983

On 1 September 1983, Korean Air Lines Flight 007 was shot down by Soviet Su-15 interceptors after straying into Soviet airspace. All 269 people aboard died — 246 passengers and 23 crew.

The aircraft was HL7442, a Boeing 747-230B, flying New York to Seoul via Anchorage.

What went wrong

The cause was mundane and, once understood, alarmingly easy.

The autopilot was left in HEADING mode rather than being switched to INS mode, which would have made it follow the programmed route from the inertial navigation system. In heading mode the aircraft simply holds a compass heading — so instead of tracking the route, it flew a constant heading and drifted steadily further from it.

Over several hours that drift took the aircraft more than 160 nautical miles off course, across the Kamchatka Peninsula and Sakhalin Island. Soviet air defence tracked it, could not identify it as a civil aircraft, and treated it as a US reconnaissance flight — plausible to them because a US RC-135 had been operating in the same region.

The crew had no idea they were off course. Nothing in the cockpit told them.

Why it mattered beyond aviation

This was the Cold War at its coldest, and the shootdown became a major international incident. But its longest-lasting consequence has nothing to do with politics.

The reason your phone knows where it is traces back to this accident.

At the time the Global Positioning System was a United States military programme, still under development and not intended for public use. In response to KAL 007, President Reagan issued a directive that GPS should be made freely available for civilian use once it was sufficiently developed, as a common good — precisely so that a civil aircraft could never again be uncertain of its own position.

Every satnav, every phone map, every modern airliner’s navigation display descends from that decision.

What it says about automation

The accident is still taught as a case study in mode confusion — the crew believing the automation was doing one thing while it did another.

The aircraft behaved perfectly. The autopilot did exactly what it had been set to do. Nobody noticed that what it had been set to do was not what was wanted, and nothing in the design made the discrepancy obvious.

That problem did not go away with better equipment; it is the reason modern flight decks put so much effort into displaying what mode the automation is actually in. The 747-400’s glass cockpit, which arrived five years later, made mode annunciation far more prominent than the analogue flight decks it replaced.

Related

• All 747 accidents
• The 747-200
• The flight deck, from three crew to two