EMERGENCY Air Canada #AC624 The pilot had to land without ILS

The pilot who crash-landed in Halifax early Sunday had to bring the aircraft in without benefit of an instrument landing system on the ground, according to a retired Transport Canada aviation inspector.

Jock Williams told CBC Tuesday the pilot used the “back course,” which he described as “the poor sister of the instrument landing system.”

The instrument landing system works with the plane’s autopilot and sends signals between the ground and the plane, letting the plane get lower to the ground as it approaches the runway, regardless of poor visibility. That increases the chances of a safe landing in bad weather.

Halifax does have ILS, but it’s only on one end of the runway that was in use Sunday. Given the weather and wind direction, the pilot used the other end of the runway.