The unsolved mystery of the 1999 'ghost flight' accident

In 1999, a plane followed a strange route in the United States skies. It took off from Florida and climbed to the intended altitude, but instead of flying towards Dallas, where it was supposed to go, it started flying straight over the US towards Canada.

The crew couldn't be contacted and military aircraft were scrambled to accompany and even intercept the Phantom Flight, fearing the worst.

However, what nobody knew at that time was that everyone on board the plane was either unconscious or deceased.

The aircraft, a Learjet 35 registered as flight number N47BA, was a private jet carrying several important individuals. They departed from Orlando, Florida on October 25, 1999. Among the passengers were golf legend Payne Stewart, former football star Robert Fraley, the president of Stewart Golf Agency, Van Arden and Bruce Borland, a golf course architect from Jack Nicklaus' company.

The plane also had two pilots, Michael Kling and Stephanie Belgrigg, for whom it was a routine trip to Dallas, Texas. In total, six people were on board the small aircraft, which was set for a leisurely three-hour flight.

They took off as usual and began climbing to the pre-approved altitude of 11,900 meters (39,000 feet) above sea level. At 7,000 meters (23,000 feet), radio contact was confirmed by the pilot, indicating that everything was in order. That was the last communication received from the plane.

Six minutes later, an attempt was made to get in contact with the plane, but there was no response. Multiple subsequent attempts to get in contact, but failed. Red warning lights flashed, alarm bells rang and it was time for the Air Force to intervene.

An F-16 fighter jet in the area flew to intercept the Learjet and perform a visual inspection.

Colonel Olson, the pilot of the fighter jet, had said that there was no visible damage to the Learjet and it was flying straight, but he couldn't see what was happening in the cockpit and identify the crew. The windows were sealed, appearing to be covered in a layer of water or ice.

Two additional jets were dispatched later for further investigation, confirming the growing concern. According to some Pentagon reports, there was consideration of shooting it down in case the plane entered populated airspace. However, these reports were denied, claiming that it was never a viable option.

Nevertheless, former Canadian prime minister, Jean Chretien, admitted later in a book he wrote that if the Learjet 35 had entered Canadian airspace, there would have been authorization to shoot it down due to the fear of it crashing into the city of Winnipeg.

As the aircraft only carried fuel for four and a half hours of flight, when it ran out, it began a spiraling descent. Eyewitness accounts noted that it appeared to have lost control and was heading toward the ground at almost supersonic speed. 

It crashed on flat ground in South Dakota, completely destroying the aircraft and leaving a large crater.

So, what happened to the crew?

After the investigation, it was determined that there had been a drastic loss of cabin pressure throughout the aircraft. It is unclear why this happened, but the crew was unable to obtain any oxygen and lost consciousness due to hypoxia.

The others on the plane quickly realized they were deprived of air and lost consciousness due to the drop in oxygen levels, which is what happened to the pilots.

The autopilot then maintained the aircraft's altitude and flew straight until the fuel ran out. For nearly four hours, the plane flew without anyone controlling it.

To this day, it remains unclear why the sudden loss of cabin pressure happened. Findings from the black box recordings indicated that no one was responsive during the final minutes of the flight and it is possible that the entire crew lost consciousness right after their last known contact with air traffic control.

Findings from the wreckage indicated that the pressure valve of the oxygen bottle that was supposed to be activated in the event of a dip in air pressure was open and the simulation team determined that, assuming the oxygen bottle contained an adequate supply of oxygen, additional oxygen should have been available to the oxygen masks for the two pilots. It is still unknown why that didn't happen.

The safety board was unable to determine why the crew couldn't or didn't receive supplemental oxygen in sufficient time and/or at an adequate concentration to prevent hypoxia and loss of functional capacity.

A report by the National Transportation Safety Board showed that the plane underwent several maintenances related to cabin pressure in the months leading up to the crash. Investigators were unable to determine whether the jobs were due to a common problem - replacements and repairs were documented, but no reports of pilot discrepancies that caused the repairs or the frequency of such reports were found.

A memorial now stands at the site of the crash, dedicated to the victims of the tragic accident, but we will never know what really happened aboard Learjet 35.