A Christchurch pilot stressed by aftershocks completed an unsafe landing in fog where he first saw the runway when he was just 30 metres above it.
The pilot made a serious safety error when he did not pull out of the landing at an altitude of 60 metres, the Transport Accident Investigation Commission (TAIC) said in a report released today.
The October 29, 2011, Air New Zealand flight from Auckland to Christchurch was carrying six crew members and 128 passengers at the time.
As the plane came in to land, the pilot reached a "decision height" of 60 metres.
At this point he was supposed to decide if he had the required visual reference to continue the landing, such as being able to see the runway approach lights.
If he did have visual reference, he was permitted to continue descending to land.
If he did not have the required visual reference, it was mandatory to initiate a "missed approach" and "go around" for another attempt.
The plane was still in cloud or fog when it reached the decision height, but the captain did not initiate a missed approach.
Both the first officer and a check captain, who was completing an annual route check with the captain, were about to intervene when the runway approach lights became visible at a height of about 30 metres.
The captain then landed the plane.
The TAIC report said the pilot should have initiated the missed approach.
Before reaching the decision height, the captain also failed to respond to two other procedural check calls, and these two failures went unchallenged by the first officer, which was another safety issue, the report said.
The report determined the captain did not comply fully with procedures or perform the mandatory missed approach because he was under stress brought on by a combination of factors.
These included the Canterbury earthquakes and their aftershocks, personal health issues and anxiety associated with the route check flight.
"The captain said that his health and the aftershocks had added to the stress under which he was operating at the time of the incident," the report said.
The captain said he had dealt well with the major earthquakes but ongoing aftershocks had caused him stress.
Air New Zealand offered all its staff counselling after the quakes, but the pilot did not take up the offer.
The captain said he might also have succumbed to a phenomenon commonly referred to as continuation bias, where a pilot believes they can continue with a flight plan or goal despite adverse changes in conditions.
Air New Zealand used the incident to reinforce to its pilots the need to follow standard operating procedures, and initiated a range of other safety actions, the report said.