A Pacific Southwest Airlines jet collided mid-air with a small Cessna over San Diego, California on September 25, 1978. In the accident, 153 people were killed, while the wreckage of the airplanes fell into highly populated neighborhoods.

(Welcome to Today in History, the series where we dive into important historical events that have had a significant impact on the automotive or racing world. If you have something you’d like to see that falls on an upcoming weekend, let me know at eblackstock [at] jalopnik [dot] com.)

David Lee Boswell was flying the Cessna 172 with his instructor Martin Kazy, the two undergoing a flying lesson on that fated morning. Boswell had completed several successful passes, then decided to head back toward the Montgomery Field airport.

Boswell was told to keep his Cessna below 3,500 feet altitude to avoid approaching Pacific Southwest Flight 1982, which was approaching San Diego. Boswell not only ignored the air-traffic controllers on that front, but he also changed course without informing anyone.

The pilots of Flight 182 also failed to inform air-traffic controllers that they had lost sight of the Cessna.

In the air-traffic control center, a collision alert system went off. It was ignored; the system frequently rang with false alarms. Because it was the last they’d heard, air-traffic controllers assumed Flight 182 pilots could still see the Cessna. One minute later, the flights collided, bursting into a massive fireball upon impact.

All 144 people on Flight 182 were killed, along with both Cessna pilots. The debris that fell on San Diego destroyed 22 homes and killed seven people on the ground in addition to those killed in the air. It remains the deadliest air disaster in California history and was, at the time, the deadliest commercial air disaster in the United States. It also renewed a longstanding controversy over the San Diego Airport’s location near heavily populated areas.