3 ms·

Hmm. So why not use that technique _all_ of the time?

• sokoloff 8y ago
  Well, AC759 should have been doing so, even on the visual approach to 28R. On this particular approach (in contrast to literally every other approach in the FMS's database), a manual tuning step was required and skipped.-[0] If there were another approach that required manual tuning and it was not a visual approach, the crew would detect they didn't have a localizer/equivalent to follow and would identify the missed step, because that's the only way they could navigate to the airport/runway. It's a specific combination of visual approach and the only approach that required manual tuning (and not having another aircraft to follow visually) that setup this possible outcome. Then, the crew visually acquires the wrong bit of pavement and there's no safety mechanism inside the airplane remaining unless/until the pilots see that they're lined up wrong or get a go-around call from ATC/another aircrew. [0] - Quote from the NTSB report: The FMS Bridge visual approach to runway 28R was the only approach in Air Canada’s Airbus A320 database that required manual tuning for a navigational aid, so the manual tuning of the ILS frequency was not a usual procedure for the flight crew.