Mode Confusion During a Late Runway Change
A two-pilot crew is on a night approach in a twin-jet after a 13-hour duty day. At 4,000 ft and 12 nm from the airport, ATC changes the landing runway from 27 to 21 and clears them for an RNAV approach. The captain is pilot flying and is tired; the first officer is pilot monitoring. The first officer programs the FMS for Runway 21 and arms LNAV, but the captain has left the autopilot in HDG mode and is steering with the heading bug. The captain believes LNAV is active. The aircraft begins to turn through the final approach course. The first officer notices the deviation but hesitates because the captain is senior and has already said, I have it. The aircraft is at 3,200 ft, 2,000 ft above the missed-approach altitude, and the localiser-like guidance is now showing a large lateral error. The weather is night visual, and the airport is in sight.
1. Identify the threats and errors in this scenario and explain how they combined.
Read the worked answer
The threats are night operation, fatigue after 13 hours, a late runway change, and a compressed approach briefing. The errors are mode confusion, incomplete monitoring, and an authority gradient that stops the first officer from speaking. The captain selected heading and believed LNAV was active; the first officer saw the lateral deviation but did not challenge. Fatigue increases the chance of fixation and slows error detection. The late change increased workload at the very time the crew needed to reconfirm the automation status. The error was not a single mistake but a chain: incomplete mode verification, poor communication, and delayed challenge. The resulting risk was an unstabilised approach and possible controlled flight into terrain or loss of separation.
2. What should the first officer say and do, using CRM principles?
Read the worked answer
The first officer should speak clearly and specifically rather than hint. A useful call is: Stop, we are in HDG mode, not LNAV; we are left of course. The captain should be told the deviation and the automation state, not just asked whether everything is okay. The first officer should then support a go-around: Go around, climb to 4,000 ft, heading 210. If the captain does not respond, the first officer must be prepared to take control or call for the other pilot to take control, because the safety of the aircraft overrides rank. Assertiveness should be calibrated: clear, early, and focused on the aircraft state. After the go-around, the crew should debrief the mode confusion and reset the approach.
3. What procedures would reduce the chance of this happening on the next approach?
Read the worked answer
The crew should brief any runway change fully, including the automation mode, armed modes, and missed-approach plan. After a change, both pilots should verify the mode annunciator and call out the active and armed modes. The pilot monitoring should be explicitly responsible for mode and path monitoring, not just radio calls. The crew should use a stable-approach gate: if the aircraft is not on the correct lateral or vertical path by a defined point, they go around. Fatigue should be managed through prior rest, strategic caffeine use, and a sterile cockpit during the approach. A short debrief after the event should identify the authority-gradient problem and agree on a phrase for a challenge. The captain should invite challenge and respond to it without defensiveness.