Comment by xeonmc
1 day ago
Here's another one:
Air Canada 143
- Pilot calculated incorrect fuel due to metric/imperial unit mixup, and ran out of fuel midair.
- Said pilot performed an impossible glider-sideslip maneuver to rapidly bleed airspeed just-in-time for an emergency landing at an abandoned airfield, having to completely rely on eyeballing the approach.
- No fatalties or serious injuries.
It was a series of events and failures rather than simply “pilot calculated incorrect”. And it was a bit more nuanced than metric/imperial conversion.
Via wiki (but accident section is more detailed):
“ The accident was caused by a series of issues, starting with a failed fuel-quantity indicator sensor (FQIS). These had high failure rates in the 767, and the only available replacement was also nonfunctional. The problem was logged, but later, the maintenance crew misunderstood the problem and turned off the backup FQIS. This required the volume of fuel to be manually measured using a dripstick. The navigational computer required the fuel to be entered in kilograms; however, an incorrect conversion from volume to mass was applied, which led the pilots and ground crew to agree that it was carrying enough fuel for the remaining trip. ”
https://en.m.wikipedia.org/wiki/Gimli_Glider
It's not an impossible maneuver. Glider pilots do this all the time especially if they don't have spoilers
Also with additional control difficulty due to reduced hydraulic pressure.
> On the Boeing 767, the control surfaces are so large that the pilots cannot move them with muscle power alone. Instead, 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,[10] and drives a hydraulic pump to supply power to hydraulic systems.
> As the aircraft slowed on approach to landing, the reduced power generated by the ram air turbine rendered the aircraft increasingly difficult to control.[16]
> The forward slip disrupted airflow past the ram air turbine, which decreased the hydraulic power available; the pilots were surprised to find the aircraft slow to respond when straightening after the forward slip.
Yes. On a plane which is designed to be a good glider. I highly doubt a 767 is designed to be a glider. It's definitely not impossible (after all, it was done successfully!), but certainly a very difficult (and undocumented) one on such a plane.
I don’t think there’s much connection between a plane’s ability to do a sideslip and how well it glides. A sideslip is just what naturally happens if you apply opposite aileron and rudder inputs. I think the issue is just that it’s a rather acrobatic maneuver to perform in a large passenger jet.
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I would say it is much much harder. The wing configuration of an aircraft dictates the minimum glide speed. The more angled (for a better word) the wing, the higher the speed it needs to be at to be able to glide and not stall.