To minimise customer impact, Air New Zealand is proactively adjusting schedules where possible, the ministry report says.

Engineering-related cancellations represented the largest share of scrubbed flights across Air New Zealand’s transtasman network.

“Airport infrastructure upgrades, such as those in Sydney and Brisbane, have also contributed to on-time performance variations.”

Weather-related cancellations also had a noticeable impact, with around 10% of cancellations.

Air NZ’s chief operating officer Alex Marren today apologised to customers affected by the global engine availability problems which contributed to most of the delays, along with higher weather impact in October.

Seasonal wind patterns during the period covered in this report often result in flights being held at the gate pre-departure to avoid early arrivals into busy airports like Sydney and Melbourne when there is the potential for a ‘fast crossing’ due to tailwinds.

‘’This drives a difference between on-time departure and on-time arrival, as is reflected in the data.‘’

She said the airline’s cancellation rate for the Tasman improved significantly to 1.3% in November.

Qantas’ OTP for departures ranged from 57% to 68% for the four months.

It blamed seasonal weather-related delays, including fog, icing, storms, winds, and industry congestion, exacerbated by weather conditions (primarily in Sydney, but also in Auckland in July).

Boarding delays happened during the school holidays. Qantas subsidiary Jetstar, had OTP for departures ranging from 69% to 75% during the period.

It told the ministry that the CrowdStrike outage on Friday July 19 hit Jetstar harder than most other carriers due to its greater reliance on Microsoft systems.

It suffered from bad weather in August and September, leading to some diversions and congestion in Sydney leading to the late departure and arrival of flights from August to October.

Emirates’ flights between Sydney and Christchurch departed on time between 51% and 71% of the time. But it had no cancellations.

Emirates told the ministry that a number of their flight delays from Sydney to Christchurch are due to the late arrival of the flight from Dubai. Depending on flight times, Emirates may hold at Dubai to prevent an early arrival into Sydney (prior to the airport opening with a 6am curfew).

There are multiple flights arriving/departing Sydney as the airport opens, resulting in flights holding, traffic congestion on taxiways and long taxi requirements.

Virgin Australia, which flies only to Queenstown, reported between 79% and 89% of flights departed on time.

For July, OTP over all transtasman routes covered by the report (on routes where there is competition) was 61.3% for on-time departures and 66% for on-time arrivals. Arrivals make better reading for airlines as aircraft can make up time en-route.

For August OTP was 68.1% for on-time departures and 70.7% for on-time arrivals.

For September, OTP was 66.1% for departures and 68.7% for arrivals.

For October, OTP was 66.2% for departures and 72% for arrivals.

This is the first time the ministry has reported on transtasman OTP following the publication on domestic OTP for Air NZ and Jetstar from midyear as part of a push from Transport Minister Simeon Brown to improve transparency among airlines.

While transtasman punctuality slipped for Air NZ in October, its domestic flights were on time more often than its Australian rival Jetstar that month.

Air New Zealand recorded 83.8% for on-time departures in October, and Jetstar 77% per cent.

For on-time arrivals in October, Air New Zealand recorded 85.5% and Jetstar recorded 78.8%.

Air New Zealand’s October cancellation rate was 0.7% and Jetstar’s was 2%.

Grant Bradley has been working at the Herald since 1993. He is the Business Herald’s deputy editor and covers aviation and tourism.