The search goes on for a medical helicopter that disappeared Monday evening in the snow and heavy winds of coastal Alaskan terrain while carrying a patient and medical crew.

Authorities were joined by volunteers Tuesday in the search for the LifeGuard Alaska helicopter that vanished Monday evening while transporting a patient and medical crew to the Providence Alaska Medical Center in Anchorage, reports the Associated Press.

The Eurocopter BK 117 carried a patient, pilot, paramedic and nurse.

The Anchorage Daily News reported Wednesday, Dec. 5, that the patient is a woman named Gay McDowell, co-owner of the Cordova Rose Lodge, who was on her way to Providence Alaska Medical Center to be treated for complications following breast cancer surgery. She was joined by nurse John Stumpff, a paramedic and a pilot, the paper adds.

The helicopter had left from Cordova, in a flight that usually takes 90 minutes, hospital spokeswoman Becky Hultberg said.

The crew was required to report the aircraft’s position every 10 minutes, Hultberg said. The helicopter crew made a satellite phone call at 5:18 p.m., but it was not a distress call, Coast Guard Lt. John McWhite said, reports the AP.

The crew failed to make the following expected contact with the medical center and the hospital launched its overdue plane procedures at 5:50 p.m. The helicopter was reported missing to the Alaska Air National Guard's Rescue Coordination Center at 6:55 p.m., Hultberg said.

The helicopter’s last known position is over the southeast side of Esther Island in Prince William Sound, about 75 miles southeast of Anchorage. A Coast Guard cutter was surveying the area Tuesday, listening for signals from the helicopter's emergency beacon. Three fishing boats maneuvered by volunteers had joined the search, under the direction of Alaska State Troopers.

The search was hindered by poor visibility and blowing snow. A low cloud ceiling prevented aircraft from taking part, Col. Dave Lowell, director of operations for the Alaska National Guard, told the AP.

Lowell said the search would continue despite the poor visibility, “until it's not plausible or reasonable to go on.”