What can the 'black box' tell us about plane crashes?

It's one of the most important pieces of forensic evidence following a plane crash: The so-called “black box."

There are actually two of these remarkably sturdy devices: the cockpit voice recorder and the flight data recorder. And they're typically orange, not black.

Federal investigators on Friday recovered the black boxes from the passenger jet that crashed in the Potomac River just outside Washington on Wednesday, while authorities were still searching for similar devices in the military helicopter that also went down.

One recovered flight data recorder was in good condition and its information is expected to be downloaded shortly. Water had gotten inside the cockpit voice recorder, which will make downloading the data more difficult. The collision killed 67 people in the deadliest U.S. aviation disaster since 2001.

Here is an explanation of what black boxes are and what they can do:

The cockpit voice recorder and the flight data recorder are tools that help investigators reconstruct the events that lead up to a plane crash.

They're orange in color to make them easier to find in wreckage, sometimes at great ocean depths. They're usually installed a plane's tail section, which is considered the most survivable part of the aircraft, according to the National Transportation Safety Board’s website.

They're also equipped with beacons that activate when immersed in water and can transmit from depths of 14,000 feet (4,267 meters). While the battery that powers the beacon will run down after about one month, there’s no definitive shelf-life for the data itself, NTSB investigators told The Associated Press in 2014.

For example, black boxes of an Air France flight that crashed in the Atlantic Ocean in 2009 were found two years later from a depth of more than 10,000 feet, and technicians were able to recover most of the information.

If a black box has been submerged in seawater, technicians will keep them submerged in fresh water to wash away the corrosive salt. If water seeps in, the devices must be carefully dried for hours or even days using a vacuum oven to prevent memory chips from cracking.

The electronics and memory are checked, and any necessary repairs made. Chips are scrutinized under a microscope.

The cockpit voice recorder collects radio transmissions and sounds such as the pilot’s voices and engine noises, according to the NTSB's website.

Depending on what happened, investigators may pay close attention to the engine noise, stall warnings and other clicks and pops, the NTSB said. And from those sounds, investigators can often determine engine speed and the failure of some systems.

Investigators are also listening to conversations between the pilots and crew and communications with air traffic control. Experts make a meticulous transcript of the voice recording, which can take up to a week.

The flight data recorder monitors a plane's altitude, airspeed and heading, according to the NTSB. Those factors are among at least 88 parameters that newly built planes must monitor.

Some can collect the status of more than 1,000 other characteristics, from a wing's flap position to the smoke alarms. The NTSB said it can generate a computer animated video reconstruction of the flight from the information collected.

NTBS investigators told the AP in 2014 that a flight data recorder carries 25 hours of information, including prior flights within that time span, which can sometimes provide hints about the cause of a mechanical failure on a later flight. An initial assessment of the data is provided to investigators within 24 hours, but analysis will continue for weeks more.

At least two people have been credited with creating devices that record what happens on an airplane.

One is French aviation engineer François Hussenot. In the 1930s, he found a way to record a plane's speed, altitude and other parameters onto photographic film, according to the website for European plane-maker Airbus.

In the 1950s, Australian scientist David Warren came up with the idea for the cockpit voice recorder, according to his 2010 AP obituary.

Warren had been investigating the crash of the world’s first commercial jet airliner, the Comet, in 1953, and thought it would be helpful for airline accident investigators to have a recording of voices in the cockpit, the Australian Department of Defence said in a statement after his death.

Warren designed and constructed a prototype in 1956. But it took several years before officials understood just how valuable the device could be and began installing them in commercial airlines worldwide. Warren's father had been killed in a plane crash in Australia in 1934.

Some have suggested that it stems from Hussenot's device because it used film and “ran continuously in a light-tight box, hence the name ‘black box,'” according to Airbus, which noted that orange was the box's chosen color from the beginning to make it easy to find.

Other theories include the boxes turning black when they get charred in a crash, the Smithsonian Magazine wrote in 2019.

“The truth is much more mundane,” the magazine wrote. “In the post-World War II field of electronic circuitry, black box became the ubiquitous term for a self-contained electronic device whose input and output were more defining than its internal operations.”

The media continues to use the term, the magazine wrote, "because of the sense of mystery it conveys in the aftermath of an air disaster.”

In this image provided by the U.S. Coast Guard, wreckage is seen in the Potomac River near Ronald Reagan Washington National Airport, Thursday, Jan. 30, 2025 in Washington. (Petty Officer 2nd Class Taylor Bacon, U.S. Coast Guard via AP)

In this image provided by the National Transportation Safety Board, NTSB investigators deliver the cockpit voice recorder and flight data recorder to NTSB headquarters in Washington, Thursday, Jan. 30, 2025, that were recovered from the American Airlines passenger jet that crashed with an Army helicopter Wednesday night near Ronald Reagan Washington National Airport. (NTSB via AP)

In this image provided by the National Transportation Safety Board, a NTSB investigator examine cockpit voice recorder and flight data recorder in Washington, Thursday, Jan. 30, 2025, recovered from the American Airlines passenger jet that crashed with an Army helicopter Wednesday night near Ronald Reagan Washington National Airport. (NTSB via AP)

In this image provided by the National Transportation Safety Board, NTSB investigators examine the flight data recorder in Washington, Thursday, Jan. 30, 2025, recovered from the American Airlines passenger jet that crashed with an Army helicopter Wednesday night near Ronald Reagan Washington National Airport. (NTSB via AP)

In this image provided by the National Transportation Safety Board, NTSB investigators examine cockpit voice recorder and flight data recorder in Washington, Thursday, Jan. 30, 2025, recovered from the American Airlines passenger jet that crashed with an Army helicopter Wednesday night near Ronald Reagan Washington National Airport. (NTSB via AP)

CONCORD, N.C. (AP) — Kyle Busch died after severe pneumonia progressed into sepsis, resulting in rapid and overwhelming associated complications, according to a statement released by his family.

Dakota Hunter, vice president of Kyle Busch Companies, said in a news release the family received the medical evaluation on Saturday.

Busch, a two-time NASCAR champion, died at 41 on Thursday, a day after passing out in a Chevrolet simulator.

Sepsis is considered a life-threatening medical emergency that occurs when the body has an extreme, overactive response to an infection, causing the immune system to damage its own tissues and organs, according to the Centers for Disease Control and Prevention.

Typically the immune system releases chemicals to fight off pathogens like bacteria, viruses or fungi, but with sepsis the response goes into overdrive. The results can cause widespread inflammation, form microscopic blood clots and make blood vessels leak.

Busch was thought to have had a sinus cold while racing at Watkins Glen on May 10 and radioed in to his team saying that he needed a “shot” from a doctor after the race.

However, he bounced back to win the Trucks Series race at Dover last weekend, and then he finished 17th in the All-Star race on Sunday.

Busch, who was preparing to race Sunday at the Coca-Cola 600 at Charlotte Motor Speedway, was testing in the Chevrolet racing simulator in Concord on Wednesday when he became unresponsive and was transported to a hospital in Charlotte, several people familiar with the situation told The Associated Press.

During the emergency call placed late that afternoon, an unidentified caller calmly told the dispatch: “I’ve got an individual that’s (got) shortness of breath, very hot, thinks he’s going to pass out, and is producing a little bit of blood, coughing up some blood.”

The caller said Busch was lying on the bathroom floor inside the complex and told dispatch “he is awake,” according to audio provided by the Cabarrus County Sheriff’s Office. The man then gave directions on where emergency responders should go and asked that they turn off any sirens upon arrival.

NASCAR driver Brad Keselowski said he knew Busch wasn’t feeling well recently.

“Yes, but I won’t go into any specifics," Keselowski said. “But then when he ran the Truck race last week, those (thoughts) were honestly kind of erased in my mind.”

Keselowski said running multiple races on the same weekend can be difficult on a driver's health — but most don't want to miss a race for fear of being replaced.

“There’s no shortage of drivers that would love to take my seat or anybody else’s seat if we weren’t feeling well, and I think every driver feels that pressure,” Keselowski said. “All athletes do. It’s not unique to NASCAR in that sense. We’re all thinking to ourselves, ‘I don’t wanna be replaced.’ ... So you try to power through it the best you can."

Busch won 234 races across NASCAR’s top three series over his two-decade career, more than any driver in history.

All 39 drivers in the field for Sunday’s race will race with a black No. 8 decal on their car to honor Busch.

AP auto racing: https://apnews.com/hub/auto-racing

An in memoriam photo of former driver Kyle Busch is displayed on the video board of the backstretch at Charlotte Motor Speedway, Friday, May 22, 2026, in Charlotte, N.C. (AP Photo/Matt Kelley)

FILE - Kyle Busch waits for the start of a NASCAR Xfinity Series auto race Saturday, June 19, 2021, in Lebanon, Tenn. (AP Photo/Mark Humphrey, File)