Bad weather and aircraft availability left 12 Defence Force staff stranded in Antarctica for a month with a rapidly closing window to get out before winter.

Crew on a Hercules aircraft finally managed to fly them home on April 17 as part of a medical evacuation for an American at McMurdo Station.

That was four weeks after they were supposed to leave on March 18.

ACT Party Defence spokesperson Mark Cameron said if it had not been for that flight they would have been stuck there even longer.

However, the Defence Force said a United States C-17 had been arranged to transport the remaining passengers back to Aotearoa.

Over the summer season, more than 200 Defence Force personnel were involved in Operation Antarctica working in various teams providing crucial logistics and maintenance support to Antarctica, New Zealand and the United States teams.

The Defence Force said some of the deployments for the Scott Base Support team were in stints of about six months, and personnel spent most of their time on the ice.

A deployment to Antarctica included different experiences from learning to survive in temperatures as low as -40C, to exploring the environment.

The summer season was supposed to end in March with the remaining 12 personnel due to return March 18, but that was not able to happen and they were stuck.

The Defence Force said numerous weather delays and aircraft availability constraints prevented their return.

"Flight operations to Antarctica are complex and require careful consideration of runway state, weather, daylight windows and even solar flare activity that can disrupt communications.

"As such, there are often extended periods when aircraft are unable to safely get to Antarctica."

It could be particularly difficult during the spring and autumn equinox periods when the rapidly changing weather, coupled with diminishing daylight windows, caused more flight cancellations, it said.

The NZDF aircraft have different limitations when it comes to flying safely to Antarctica which hindered the team's return.

NZDF said the Boeing 757's last safe day to fly to Antarctica was March 22 – just four days after the deployment was supposed to end.

An unsuccessful attempt was made on this day.

The Hercules, which the team eventually managed to hitch a ride on, had a longer window of travel to Antarctica.

In recent times the Defence Force had also struggled with critical staff shortages, supply chain delays for aircraft parts and some were just becoming obsolete.

In 2021, the Hercules did manage to safely conduct a winter flight for a medical evacuation using night vision goggles to land.

At the time, RNZAF Base Auckland commander group captain Andy Scott said: "Flying to Antarctica is one of the highest risk missions we fly due to the lack of divert airfields and inability to get down and back without refuelling.

"The crews therefore are highly trained to analyse the situation with regards to the weather and the airfield state before making a decision to proceed.

"Flying in winter presents even more challenges due to the extreme cold, the rapidly changing weather and little to no visual warnings of the changes you would 'see' in summer."

ACT Party's Cameron said he was in contact with the team in Antarctica and said the whole situation was very difficult for those on the ground.

He said they worried that if there had not been a medical emergency, they might not have got out when they did.

They may have been stranded for longer in an isolated research station, separated from loved ones, with plummeting temperatures and no certainty about when or how they would get home.

NZDF said despite having a flight scheduled for the remaining passengers, they used the Hercules as an opportunity to return the team home.

Cameron said the team had also told him communication between NZDF officials was lacking.

"And by virtue these few people felt metaphorically, you might say, abandoned.

"[It's] not good enough."

The Defence Force rejected that.

"There was regular communication with our personnel in Antarctica, who as professional NZDF service people also understand that there can be weather-related or other delays while deployed."

The return of the team marked the end of the Antarctica season for NZDF.