What is a black box on a plane? What to know after AA Flight 5342 crash with helicopter

As the recovery operation continued after a commercial airliner collided with an Army helicopter near the nation's capital this week, federal aviation officials announced Thursday they had recovered the so-called black boxes from the airline passenger plane.

The National Transportation Safety Board (NTSB), the lead agency handling the deadly crash, held a briefing Thursday afternoon. During the news conference, NTSB member Todd Inman said the military helicopter was also equipped "with some form of recording."

"We feel comfortable and confident" the boxes would be recovered, Inman told reporters.

A preliminary report about the incident is expected within 30 days, officials said.

The fatal crash took place just before 9 p.m. Wednesday when American Airlines Flight 5342 attempted to land and collided in midair with a Black Hawk trying to land at the Ronald Reagan Washington National Airport (DCA) in Arlington, Virginia.

Flight 5342 took off from Wichita, Kansas, at 5:18 p.m. CST and was set to land at DCA at 9:03 p.m. ET, but dropped out of the air on approach at about 8:48 p.m., according to aircraft tracking site FlightAware.

Live updates: 'We will find out what happened,' NTSB vows after tragic midair collision

The passenger plane with 64 people aboard then fell into the icy waters of the Potomac River. The Black Hawk helicopter carried three people.

All aboard both aircraft are feared dead, officials said during Thursday morning news conferences.

What is the black box, what can it tell us, and how do they work?

Here's what to know:

What is a black box?

A black box is a flight data recorder that collects information on communications involving pilots in cockpits and how the aircraft systems perform in-flight.

It is designed to be practically indestructible.

???Large commercial aircraft and some smaller commercial, corporate, and private aircrafts are required by the Federal Aviation Administration to be equipped with two black boxes, according to the NTSB.

The first, called the Cockpit Voice Recorder, records radio transmissions and sounds in the cockpit including pilots' voices and engine noise, according to the federal agency. The second is called a Flight Data Recorder, which monitors parameters such as altitude, airspeed, and heading.

The recorders are installed to help reconstruct precisely what happened leading up to a crash.

Where is a black box found on a plane?

A black box is typically found in the aircraft's rear.

Each box is equipped with an Underwater Locator Beacon in the event of an overwater crash, according to NTSB. Dubbed a "pinger", the device is activated when the recorder is submerged in water, according to a NTSB online fact sheet. "

"It transmits an acoustical signal on 37.5 KHz that can be detected with a special receiver," the sheet reads. "The beacon can transmit from depths down to 14,000 feet."

What happens when a black box is recovered from water?

If a black box is recovered from the water, it is immersed in fresh, clean water to prevent deposits such as salt or minerals from drying out within the device, said John Cox, a retired airline captain with former US Airways.

"When the technicians at the laboratory are ready to download the data, they take the recorder out of the freshwater bath, carefully open it and dry any sections that have been exposed to water," according to Cox, who owns the aviation safety consulting company, Safety Operating Systems. "They then download the data into special computers that can read the information."

Has the black box on American Airlines Flight 5342 been located

Yes, the NTSB said divers had located the black boxes for AA Flight 5342.

Contributing: Reuters, Kinsey Crowley; USA TODAY

Natalie Neysa Alund is a senior reporter for USA TODAY. Reach her at [email protected] and follow her on X @nataliealund.

This article originally appeared on USA TODAY: Has AA Flight 5342's black box been found? What to know after crash