Editing Gimli Glider (section)

===Running out of fuel===
While Flight 143 was flying over [[Red Lake, Ontario]] at {{convert|41000|ft|-2}} shortly after 8 pm [[Central Time Zone|CDT]],<ref name=clojt /> the aircraft's cockpit warning system sounded, indicating a fuel-pressure problem on the aircraft's left side. Assuming that a fuel pump had failed, the pilots turned off the alarm, knowing that the engine could be gravity-fed in level flight.<ref name="WNelson">{{cite web |last=Nelson |first=Wade H. |date=October 1997 |title=The Gimli Glider |url=http://www.wadenelson.com/gimli.html |url-status=live |archive-url=https://archive.today/20121205003036/http://www.wadenelson.com/gimli.html |archive-date=2012-12-05 |access-date=November 9, 2013 |website=WadeNelson.com |publisher=Originally published in [[Soaring (magazine)]]}}</ref> A few seconds later, the fuel pressure alarm also sounded for the right engine. This prompted the pilots to divert to [[Winnipeg James Armstrong Richardson International Airport|Winnipeg]].

The left engine failed within seconds, and the pilots began preparing for a single-engine landing. As they communicated their intentions to controllers in Winnipeg and tried to restart the left engine, the cockpit warning system sounded again with the "all engines out" sound, a sharp "bong" that no one in the cockpit could recall having heard before.<ref name="WNelson" /> The right-side engine stopped seconds later, and the 767 lost all power. Flying with all engines out was never expected to occur, so it had never been covered in training.<ref name=Willams03>{{cite journal |last=Williams |first=Merran |date=July–August 2003 |title=The 156-tonne Gimli Glider |journal=Flight Safety Australia |pages=27 |url=http://www.casa.gov.au/wcmswr/_assets/main/fsa/2003/jul/22-27.pdf| access-date=February 20, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20120326042427/http://casa.gov.au/wcmswr/_assets/main/fsa/2003/jul/22-27.pdf |archive-date=March 26, 2012}}</ref> Adding to both the crew's and the controllers' problems, the plane's [[Transponder (aeronautics)|transponder]] failed, stopping the altitude reporting function, and forcing the controllers to revert to [[primary radar]] to track the plane.

The 767 was one of the first airliners to include an [[electronic flight instrument system]], which operated on the electricity generated by the aircraft's jet engines. With both engines stopped, the system went dead, and most screens went blank, leaving only a few basic battery-powered emergency flight instruments. While these provided sufficient information to land the aircraft, the backup instruments did not include a [[vertical speed indicator]] that could be used to determine how far the aircraft could glide.

On the Boeing 767, the [[Flight control surfaces|control surfaces]] are so large that the pilots cannot move them with muscle power alone. Instead, [[Hydraulic drive system|hydraulic systems]] are used to multiply the forces applied by the pilots. Since the engines supply power for the hydraulic systems, in the case of a complete power outage, the aircraft was designed with a [[ram air turbine]] that swings out from a compartment located beneath the bottom of the 767,<ref name="WNelson" /> and drives a hydraulic pump to supply power to hydraulic systems.