In line with their planned diversion to Winnipeg, the pilots were already descending through when the second engine shut down. They immediately searched their emergency checklist for the section on flying the aircraft with both engines out, only to find that no such section existed. Captain Pearson was an experienced glider pilot, so he was familiar with flying techniques almost never used in commercial flight. To have the maximum range and therefore the largest choice of possible landing sites, he needed to fly the 767 at the optimum glide speed. Making his best guess as to this speed for the 767, he flew the aircraft at . First Officer Maurice Quintal began to calculate whether they could reach Winnipeg. He used the altitude from one of the mechanical backup instruments, while the distance travelled was supplied by the air traffic controllers in Winnipeg, measured by the aircraft's radar echo observed at Winnipeg. In the aircraft lost , giving a glide ratio of approximately 12:1 (dedicated glider planes reach ratios of 50:1 to 70:1).