At Montreal, Captain Bob Pearson and First Officer Maurice Quintal took over the airplane for Flight 143 to Ottawa and Edmonton. During the handover, Weir told Pearson that there was a problem with the FQIS, and Pearson decided to take on enough fuel to fly to Edmonton without refueling in Ottawa. Meanwhile, an avionics technician had entered the cockpit and read the logbook. While waiting for the fuel truck, he enabled the defective channel and performed an FQIS self-test. Distracted by the arrival of the fuel truck, he left the channel enabled after the FQIS failed the self-test. Pearson entered the cockpit to find the FQIS blank, as he expected.