Alessandro Garofalo / Reuters, file

A U.S. Air Force F-16 fighter jet like the one shown flying over Aviano Air Base, Italy, is presumed to have crashed in the Adriatic Sea while on a training exercise. Aviano controllers lost contact with the plane about 8 p.m. local time Monday.

U.S. and Italian authorities searched the Adriatic Sea on Tuesday after a U.S. Air Force fighter jet was lost and presumed to have crashed.

Divers focused on waters where a fishing boat had found fragments believed to belong to the F-16, a Coast Guard official told Reuters.

Fragments of carbon steel and other debris were found floating in the northern Adriatic overnight, Rear Admiral Francesco Saverio Ferrara told Reuters. The U.S. Air Force said in a statement it believed the debris belonged to the wreckage of the missing aircraft, Reuters reported.

"We hope to find out more during the day so we can have a more complete picture of what happened," Ferrara said, according to Reuters.

Controllers lost contact with the F-16 at about 8 p.m. local time (2 p.m. ET) Monday, after it took off for a training exercise from Aviano Air Base, Italy, the Aviano-based 31st Fighter Wing said in a statement.

Italian aircraft and ships were dispatched to the missing jet's last known location, and U.S. and Italian aircraft were flying over the area Tuesday, the Air Force said.

The Italian national news agency ANSA reported that a fuel slick was seen off the coast near the town of Cervia and that a fishing boat had found fragments that could have belonged to a military jet.

Weather was bad at the time the plane vanished, with sleet falling and visibility poor, the Associated Press quoted an Italian coast guard commander as saying. 

The Italian news agency LaPresse reported that the pilot sent an alarm signal to Aviano before contact was lost and that three other planes on the training mission had made it back to the base safely.  

No information was released about the pilot, who was the plane's sole occupant.

Search-and-rescue operations are still being conducted by sea and air, Reuters reported.

"Wing leadership remains hopeful that we will safely rescue our pilot," an Air Force statement said, according to Reuters.

The Associated Press, Reuters, ANSA and LaPresse contributed to this report

Lynn M. Arnold / National Science Foundation via AP

A De Havilland Twin Otter like the one missing since Wednesday lands at the National Science Foundation's Amundsen-Scott South Pole Station in 2003.

Bad weather continued to stop rescuers from searching for a Canadian airplane that went missing in Antarctica with three people on board, officials in New Zealand rescue team said Friday. 

Though winds, which had been blowing at over 100 mph, had calmed to just over 20 mph by 5 p.m. Friday New Zealand time (11 p.m. ET Thursday), conditions would not allow sighting of the downed twin-engine airplane.

"Visibility is down to (1,300 feet) and the snow is almost horizontal," Kevin Branaghan, an official with Rescue Coordination Center New Zealand, said in a statement. "The weather is expected to improve slightly after 12-24 hours."

The plane, owned by Kenn Borek Air of Calgary, Alberta, was on its way from the U.S.-run Amundsen-Scott South Pole station to Italy’s Mario Zucchelli station while supporting an Italian research project, according to the National Science Foundation, which manages U.S. programs on the icy continent.

It took off at about 3 a.m. ET Wednesday and flew for an hour before its emergency locator beacon was detected in New Zealand, which is responsible for monitoring that section of Antarctica.

The beacon was tracked to a spot about 11,000 feet above sea level at the northern end of the Queen Alexandra Mountain range, some 400 miles from the aircraft’s departure point near the South Pole, rescue-team spokesman Michael Flyger said Thursday.

Hours of flyovers by aircraft from the United States, Canada and New Zealand proved fruitless because of cloud cover and blowing snow, he said.

'Extremely cold'
Kenn Borek Air said in a Thursday statement that weather had kept another of its planes from landing at a makeshift airbase 35 miles from the site of the locator beacon.

The company has otherwise released little information, saying it is "maintaining a respectful silence" until the fate of the plane is known.

If the plane has crashed, any survivors would have faced extreme conditions in the mountains, Rescue Coordination Center spokesman Flyger said Thursday.

"It’s a cold place to start with," he said. "The elevation is around 11,000 feet so ... combined with the wind and snow ... it’s going to be extremely cold."

Flyger noted that the crew was carrying heavy-duty, cold-weather gear and a five-day supply of water.

"We are still operating with the expectation that we will find them alive," his colleague Branaghan said Friday.

The search-and-rescue team's website, however, referred to searching for a "crash site."

Related:

100 mph winds halt search for missing plane

Plane with 3 on board missing near South Pole

(Editor's note: This story includes a correction.)

Howling winds and snow grounded an effort Thursday to find a small plane missing in a mountainous area of Antarctica for more than two days, rescuers said.

The twin-engine plane, carrying three Canadian crew members, was about an hour into a flight from the U.S.-run Amundsen-Scott South Pole Station to an Italian research station at Terra Nova Bay, when its emergency beacon was heard by rescue officials in Wellington, New Zealand, at about 10 p.m. local time Wednesday (4 a.m. ET)

The company that owns the plane, Kenn Borek Air Ltd. of Calgary, Alberta, said it was "maintaining a respectful silence" until the fate of the plane and its crew was known.

The Calgary Sun newspaper identified one of those aboard the plane as Bob Heath of the Northwest Territories, calling him a "star pilot" for Kenn Borek Air.

www.nsf.gov

A file photo shows a twin-engine Otter, the type of plane missing in Antarctica with three Canadians aboard.

The newspaper quoted Heath’s wife Lucy Heath as saying she was “worried” and “waiting for news.”

A search plane spent about five hours circling over the site of the beacon, which is in a mountainous area, but heavy cloud cover hampered the search and then the weather got worse, officials said.

Winds have topped 100 mph and it was also snowing, Michael Flyger, spokesman for New Zealand’s Rescue Coordination Center, said.

He added he hoped the next weather forecast "will bring good news,” enabling the search to continue.

Five-day water supply
The beacon’s signal is coming from an area about 11,000 feet above sea level, Flyger said.

"It’s pretty mountainous terrain. It’s impossible to say whether it crashed or made an emergency landing or they had a mechanical problem and had to ditch the plane," he said. "At the moment we have a plane that’s not where it should be and a locator beacon is going off."

The beacon can be switched on manually, but it also would begin transmitting if sensors detected a crash, Flyger said.

Despite the conditions in the area, there may be reason for optimism, he added.

"We do know that onboard the aircraft there was a significant amount of survival equipment — heavy-duty mountain tents, enough water for three people for five days,” he said. “They’ve certainly got the equipment to look after themselves."

The National Science Foundation, which manages the U.S. Antarctic Program, said the plane was flying in support of Italian Antarctic research.

Searchers from the United States, Italy and Canada are assisting in New Zealand's efforts and have helicopters and airplanes ready to return to the site, Flyger said, adding that the the ideal scenario would be for a helicopter to either land or use a winch to bring up survivors.

"If conditions are good enough, hopefully we can land a short distance away and the team will walk to the crash site," he said.  "There’s some frustration that the weather has been the way it’s been. The searchers are very keen to get in and crack on with the job."

"We’re very aware that not only are there people out there who need our help, but there are people ... wanting to know what’s going on. We hope to be able to give some good news."

Related:

Plane with 3 on board missing near South Pole