Alaska plane with 10 aboard had sudden drop in altitude and speed ...

A missing plane in Alaska that had 10 people on board Thursday, experienced a rapid loss in altitude and speed, prompting the Coast Guard to launch a search and rescue operation, officials said Friday.

On Friday afternoon, a search aircraft spotted an "item of interest" and a USCG helicopter was en route to investigate, the Coast Guard said at a news conference Friday.

Alaska State Troopers received reports at 4 o'clock local time that a Bering Air Caravan heading from Unalakleet to Nome carrying nine passengers and a pilot was overdue, according to an online statement.

There was no early word on their identities. The families of the passengers have been notified of the incident, the Nome Fire Volunteer Department said on social media on Friday afternoon. 

It was the third major U.S. aviation incident in eight days. An American Eagle flight and Army Black Hawk helicopter collided and plunged into the Potomac River near Washington, D.C., on Jan. 29, killing all 67 people on the two aircraft. And a medical transportation plane crashed in Philadelphia on Jan. 31, killing the six people on board and one more on the ground. 

Bering Air Director of Operations David Olson said the Caravan left Unalakleet at 2:37 p.m.

The Nome Volunteer Fire Department said in a Facebook post that the pilot told Air Traffic Control "he intended to enter a holding pattern while waiting for the runway to be cleared."

A Coast Guard search and rescue Hercules HC-130 aircraft was dispatched from Air Station Kodiak to the missing plane's last known location, 12 miles offshore, according to a statement on X. The search turned up empty, the Coast Guard said on Friday. Another helicopter crew is on route to the location. 

Data from FlightRadar shows a Bering Air flight last reporting information at 3:16 p.m. over Norton Sound.

The Hercules HC-130 was to fly a grid pattern over the water and along the shoreline with equipment that can help locate the plane in conditions with no visibility, the fire department said.

Joint Base Elmendorf-Richardson, in Anchorage, also sent flight support.

Ground crews have covered a stretch along the coast from Nome to Topkok, the fire department said, adding that, "We continue to expand search efforts to as many avenues as possible until the plane is located."

But "due to weather and visibility, we are limited on air search at the current time," it said. People were told not to form their own search parties because the weather was too dangerous.

Early Friday, the fire department said it doesn't "have any updated information on the location of the missing aircraft. Later in the day, the department said the Coast Guard was "actively canvassing the sea ice and shoreline." 

An FAA weather camera near Nome appeared to show near-whiteout conditions spanning several hours Thursday afternoon, Alaska's News Source reported.

It was 17 degrees Fahrenheit in Unalakleet at about the time the plane departed, light snow was falling and it was foggy, the National Weather Service said.  

The National Transportation Safety Board said it's monitoring developments, but the agency doesn't start investigations until a plane's fate is determined. It has a team stationed in Alaska year-round.

The Cessna Caravan is a single engine propeller plane that holds about 10 people, including the pilot. It's generally reliable and is widely used.

Alaska is no stranger to small plane accidents, especially during winter, when the weather can make flying very challenging. And planes are frequently the only choice for trips of any distance in rural Alaska.

Unalakleet is a community of some 690 people in western Alaska, about 150 miles southeast of Nome and 395 miles northwest of Anchorage.

Nome is known as the finish line of the 1,000-mile Iditarod. It's a Gold Rush town just south of the Arctic Circle.

Nome-based Bering Air serves 32 villages in western Alaska and also has hubs in  Kotzebue and Unalakleet. Most of the villages get scheduled flights twice a day, Monday through Saturday.

-- Kris Van Cleave and The Associated Press contributed to this report.

More from CBS News