https://www.popularmechanics.com/science/a71205820/helios-airways-flight-522/

At 11:05 a.m. on August 14, 2005, two Greek Air Force F-16 fighter jets were met with a bone-chilling sight. As the fighter jets approached Helios Airways Flight 522, which had been circling in a continuous loop over Athens in what some thought might be an impending terrorist attack, the pilots peered through the passenger aircraft’s windows into its main cabin and cockpit. Everyone inside the passenger jet appeared to be slumped in their chairs while wearing oxygen masks—including the pilot and the co-pilot. For more than an hour, Nicosia air traffic control had tried to hail the pilots to no avail, and now they knew why.

The Boeing 737—and the 121 people on board—only had one hope, a flight attendant named Andreas Prodromou, who had remained conscious thanks to a portable oxygen supply. While Prodromou held a U.K. Commercial Pilot License, he had no training in landing an aircraft of this size. Reports from the F-16 crew state that Prodromou briefly waved to the F-16 pilots from the cockpit window, tried to wake the Boeing’s pilots, and even sent a few mayday messages, but he was too late. The plane engine’s soon flamed out and the aircraft began its deadly descent, crashing into hills near the Greek village of Grammatiko just after noon local time. No one survived, leaving bewildered officials and grieving families to pick through the pieces.