By: Chris Kilroy

An amateur photographer photographed N533PS just before impacting the ground (File Photo).

Conditions were perfect for a routine scheduled flight by PSA (Pacific Southwest Airlines) Boeing 727-200 N533PS on the morning of September 25, 1978.

Flight 182 was flying the daily morning service of California's largest feeder airline from Sacramento to San Diego, via Los Angeles. While it was on the ground at Los Angeles, on and off loading passengers, a single-engine Cessna 172, N7711G, took off at 08.15am from Montgomery Field, a municipal airport seven miles northeast of San Diego's main airport, Lindbergh Field.

At the controls of the Cessna was David Lee Boswell, who was taking instrument flying lessons from his instructor, Martin Kazy. Montgomery Field was not fitted with an ILS (Instrument Landing System), so Boswell flew the seven miles to Lindbergh, and began practice approaches, simulating landings from west to east. San Diego's airport was fitted with the latest ATC equipment, as well as a computer-controlled conflict alert warning system.

Boswell has completed two practice ILS circuits and was leaving the vicinity of Lindbergh Field when the PSA 727 arrived in the area.

Lindbergh Tower told Boswell to fly north-east and to stay below 3,500ft. He complied initially, and then, without informing the ATC controllers, he changed course, bringing his Cessna on to the same path as the oncoming jet.

PSA 182 had the Cessna clearly in view at 09.00. In the course of the next minute, the experienced crew of the 727 lost sight of the Cessna as it continued its climb. Assuming that they had overtaken it, they continued with their planned approach and descent.

The wreckage of PSA Flight 182. (File Photo)

Meanwhile, the conflict alert warning system began to flash on the screens in the San Diego ATC facility. Such alerts were a common occurance in the busy Lindbergh control zone, so the tones were simply ignored. As the Boeing crew had already indicated that they had the Cessna in sight, the controllers took no further action, other than to notify the Cessna's crew once more of the jet's presence behind them. There was no acknowledgement and just three quarters of a minute later, the two aircraft collided.

The 727 was carrying more than six tons of fuel, much of it in the wing tanks. The explosion and subsequent fire-ball that followed the collision "felt like 200 degrees" according to one of the witnessses on the ground. Another said she saw her "apples and oranges bake on the trees."

Investigators determined that the 727 struck the ground in a high speed nose down attitude, while banked 50° to the right.

From the moment of impact with the Cessna, it took just 17 seconds to transform Flight 182 from a fully functional airliner in to a mass of burning wreckage spread out over four city blocks. The crash destroyed 22 houses and numerous cars in North Park, and killed 7 residents, as well as the 144 people on board the flight. The tower pilots onboard the Cessna were also killed.

Investigative Findings

1. The primary cause of the disaster was that the crew of PSA flight 182 lost sight of the Cessna and did not tell San Diego ATC that they had done so.

2. The controllers failed to appreciate that PSA 182 had lost sight of the Cessna, or even that there was some confusion as to its position. This should have been obvious from the radio transmissions recieved from the 727.

3. The possible presence of a third, unidentified and unauthorized aircraft may have confused the crew of PSA 182 as to the position of the Cessna.

4. ATC procedures were confused and poorly coordinated, allowing the controllers to authorise visual separation procedures when a radar service was available.This would have been safer, giving lateral and vertical separation between both aircraft.

5. The controller failed to advise Flight 182 as to the direction of the movement of the Cessna.

6. The pilot of the Cessna didn't maintain his assigned heading of 070 or inform ATC that he was diverting from his course. Had he maintained his position the accident would never of happened.

7. San Diego Approach Control had failed to react to the conflict alert warning (both visual and aural). No warning was passed to either pilot.

8. San Diego Approach Control did not restrict Flight 182 to a minimum height of 4,000ft while it was within the Mongomery Field traffic area. Had it done so, the collision would not have occured.