problem with the 767 was due to not taking on enough fuel in the first place. Canada & AC
had just switched to metric & everyone involved had trouble converting pounds to kilos & litres to gallons. There was also a problem with the fuel gauges onboard so the figure was programmed into the FMC manually. Unfortunately, it was not correct. With both engines flamed out the only power was provided by the Ram Air Turbine. This only ran essential systems so the landing was made with no flaps & the alternate method was used for landing gear extension. They never got a locked indication on the nose gear, but going around wasn't exactly an option.
With the Transat 330 they had enough fuel but had a severe leak because of a mismatched part on one of the engines. The pilots then decided the problem was a computer malfuntion rather than a fuel leak (there were some strange error messages). But in both cases everyone made it home, unlike United 173.
I'd rather be lucky than good