A U.S. Air Force C-17A Globemaster III turned back to Christchurch, New Zealand, after receiving a notice warning of potentially hazardous space activity along its planned route to Antarctica. The aircraft had departed Christchurch International Airport on a routine resupply mission but returned before reaching the continent.

The warning followed a notification from Russia’s Air Traffic Management Corporation to New Zealand’s Civil Aviation Authority about a planned missile launch and an associated potential hazard to international airspace within New Zealand’s Oceanic Flight Information Region, the authority said in comments reported by Defense News.

New Zealand’s CAA responded by establishing a danger area and issuing a Notice to Airmen, or NOTAM, to alert aircraft operators. The notice provided information about the potential hazard and did not prevent aircraft from flying through the area, according to a CAA spokesperson.

“This does not prevent aircraft from flying through the area,” the spokesperson said. “Operators make their decisions based on the information available.”

The CAA said NOTAMs alert aircraft operators to potential hazards so they can make operational decisions around flight planning. The authority also said it is normal practice for airspace authorities and air traffic service providers to issue NOTAMs after receiving notifications of potential hazards.

Flight-tracking data cited in the Defense News report showed the aircraft, using the call sign ICE28, took off at about 9 a.m. local time Tuesday and landed back at Christchurch around 11:30 a.m. The tracking data identified it as a C-17A Globemaster III operated by the U.S. Air Force.

The flight was a routine resupply mission scheduled for this time of year, a U.S. Pacific Air Forces spokesperson told Defense News. Christchurch is used by the U.S. Air Force and New Zealand Defence Force for operations and logistical support connected with Antarctic science programs, the spokesperson said.

The turnaround occurred during the U.S. Air Force’s annual Winter Fly-in period, known as WinFly. The seasonal operation generally takes place toward the end of August and delivers teams, equipment and cargo to McMurdo Station and Scott Base in Antarctica ahead of the research season. The Pacific Air Forces spokesperson did not comment on whether the specific flight was directly supporting WinFly.

The C-17A Globemaster III is a cargo aircraft capable of delivering troops and loads to main operating bases or forward bases in deployment areas. The aircraft can also conduct tactical airlift and airdrop missions, as well as aeromedical evacuations.

A 2012 Air Force release described WinFly as an effort to deliver advance teams and cargo from Christchurch to prepare McMurdo Station for the main season of Operation Deep Freeze. That operation supports the U.S. Antarctic Program, which is managed by the National Science Foundation. The release said a C-17 mission that year carried more than 300 passengers and 230,000 pounds of cargo to Antarctica.

Much of New Zealand’s Oceanic Flight Information Region lies over international waters, where the CAA has limited control over activities, the authority said. The region covers about 30 million square kilometers across the South Pacific Ocean, Southern Ocean and Tasman Sea.

The C-17’s return illustrates how a hazard notice can affect an operational flight without preventing aircraft from entering the area. After receiving the warning, the crew returned to Christchurch rather than continuing the planned flight to Antarctica.