GA TRK is lateral mode engages:

• when at least one thrust lever is set to TOGA detent, and
• slats or the flaps are extended, and
• aircraft is airborne, or on ground for less than 30s, and
• NAV, HDG, or TRACK is not engaged.

When GA TRK engages, NAV mode arms and if HDG/TRK was preset, NAV mode does not arm. Flight crew then pulls the HDG/TRK knob to follow the preset target.

Examples:

• for ILS approach, column 3 FMA changes from LOC to GA TRK and NAV is armed
• for NAV/FPA approach, column 3 FMA remains in NAV mode
• for laterally and vertically selected approach, HDG/TRACK remains engaged and NAV mode arms in column 3.