USAir had recently purchased
Pacific Southwest Airlines (PSA). David A. Burke, an aircraft cleaning specialist, had been recently terminated by USAir for petty theft of $69 from in-flight cocktail receipts and had also been suspected of other thefts including receipts totaling thousands of dollars.
 After meeting with Ray Thomson, his manager, in an unsuccessful attempt to be reinstated, Burke purchased a ticket on PSA flight 1771, a daily flight from
Los Angeles International Airport (LAX) to
San Francisco International Airport (SFO). Thomson was a passenger on the flight, which he regularly took for his daily commute from his workplace at LAX to his home in the San Francisco Bay Area.
Flight 1771 departed from LAX at 15:31
PST, bound for San Francisco. It was scheduled to arrive at San Francisco at 16:43, after a flight time of 1 hour 12 minutes.
Using his unsurrendered
USAir employee credentials, Burke, armed with a
Smith & Wesson Model 29
revolver that he had borrowed from a co-worker, was able to bypass the normal passenger security checkpoint at Los Angeles International Airport.
 After boarding the plane, Burke wrote a message on an airsickness bag. It is not known if he gave the message to Thomson to read before shooting him:
- "Hi Ray. I think it's sort of ironical that we end up like this. I asked for some leniency for my family. Remember? Well, I got none and you'll get none."
As the aircraft, a four-engine
BAe 146-200, cruised at 22,000 ft (6,700 m) over the central California coast, the
cockpit voice recorder (CVR) recorded the sound of someone entering and then leaving the lavatory. The
Mayday episode suggests that this was Burke entering the lavatory to draw his revolver discreetly, possibly loading it and giving Thomson time to read the note before killing him. 44-year-old pilot Gregg Lindamood and 48-year-old co-pilot James Nunn were asking air traffic control about turbulence when the CVR picked up the sound of two shots being fired in the cabin.
The most plausible theory as to what happened was deduced from the pattern and audible volume of the shots on the CVR.
 According to the
Mayday episode, it is likely that Burke first shot Thomson twice. Thomson's own seat was never recovered. Part of a seat that was identified from its serial number as being directly behind Thomson's was found to have two bullet holes in it. Due to the power of the revolver, the bullets must have traveled through Thomson's body, his seat, and then through the seat behind. First Officer Nunn immediately reported to air traffic control that a gun had been fired on board and no further transmissions were received from the crew. At that point, the CVR recorded the cockpit door opening and flight attendant Deborah Neil telling the cockpit crew, "We have a problem!" to which Captain Lindamood replied, "What's the problem?" A shot was heard as Burke shot the flight attendant dead, and announced "I'm the problem." He then fired two more rounds. Most likely, he shot the pilot and copilot once each, incapacitating them, if not outright killing them. Several seconds later, the CVR picked up increasing windscreen noise as the airplane pitched down and accelerated. The remains of the
flight data recorder (FDR) indicated Burke had pushed the control column forward into a dive.
A final gunshot was heard followed not long after by a sudden silence. It is most likely that Burke killed Douglas Arthur, PSA's Chief Pilot in Los Angeles, who was also on board as a passenger and who may have been trying to reach the cockpit to save the aircraft. There was speculation that Burke shot himself, though this seems unlikely, because a fragment of Burke's fingertip was lodged in the trigger when the investigators found the revolver. This indicated that he was alive and he was holding the gun until the moment of impact.
 The plane crashed into the hillside of a cattle ranch at 4:16 p.m. in the
Santa Lucia Mountains near
Cayucos, exploding on impact. The plane was estimated to have crashed slightly faster than the
speed of sound, at around 770 mph (1,240 km/h), disintegrating instantly. Based on the deformation of the hardened steel black box data recorder case, the aircraft experienced a deceleration of 5,000 times the force of gravity (
G-force) when it hit the ground. It was traveling at an approximately 70 degree angle toward the south. The plane struck a rocky hillside, leaving a crater less than two feet (0.6 m) deep and four feet (1.2 m) across. The remains of 27 passengers were never identified.
After the crash site was located by a
CBS News helicopter piloted by
Bob Tur, investigators from the
National Transportation Safety Board (NTSB) were joined by the
Federal Bureau of Investigation (FBI). After two days of digging through what was left of the plane, they found the parts of a handgun containing six spent cartridge cases and the note on the airsickness bag written by Burke, indicating that he may have been responsible for the crash. FBI investigators were able to lift a print from a fragment of finger stuck in the pistol's trigger guard, which positively identified Burke as holding the weapon when the aircraft crashed. In addition to the evidence uncovered at the crash site, other factors surfaced. Burke's coworker admitted to having lent him the gun, and Burke had also left a farewell message on his girlfriend's answering machine.