What is a black box on a plane, and what does it record?
The "black box" is really two recorders, one for cockpit sounds and one for flight data. US rules require them on airliners, painted bright orange or yellow and fitted with an underwater beacon. Their whole job is to help investigators learn, so the same thing doesn't happen again.
In this article · 7 sections
Two boxes, not one
"Black box" is a nickname for two separate recorders that large commercial aircraft are required to carry:1
- The cockpit voice recorder (CVR) records radio transmissions and sounds in the cockpit, such as the pilots' voices and engine noises.
- The flight data recorder (FDR) records how the airplane is flying: altitude, airspeed, heading and much more.
Both are installed in the most crash-survivable part of the aircraft, usually the tail.1
They're orange, on purpose
Despite the name, US rules for airliners require each CVR container to be bright orange or bright yellow, with reflective tape to help find it underwater and an approved underwater locating device attached.2 The NTSB says that beacon, nicknamed the "pinger", switches on in water and can be detected from as deep as 14,000 feet, with 30 days of operation once activated.1
Built to survive
The NTSB lists the recorders' survivability specifications: an impact tolerance of 3,400 G, fire resistance of 1,100 °C for 30 minutes, and water-pressure resistance when submerged to 20,000 feet.1
What the flight data recorder keeps
By regulation, newly manufactured aircraft must record at least 88 parameters, and some recorders capture more than 1,000.1 Airlines must keep at least the last 25 hours of operating data.3 Investigators use the data to build an animation of the flight and see exactly what the airplane did.1
What the cockpit voice recorder keeps
On airliners, the CVR has to run continuously from the checklist before engine start until the final checklist at the end of the flight.2 How much it keeps depends on when the airplane was built: at least the last 25 hours for airplanes manufactured on or after May 16, 2025, and at least the last 2 hours for those built earlier.2
The rules also limit how the recording is used. The FAA doesn't use it in any civil penalty or certificate action; it exists to help find the cause of accidents and incidents.2 And the NTSB never releases the audio itself: Congress requires it not to.1
After an accident
Both recorders go straight to the NTSB's laboratory in Washington, DC, where their information is extracted and turned into something investigators can use.1 A committee, typically including the NTSB, the FAA, the operator, the manufacturers and the pilots' union, listens to the CVR and produces a written transcript.1 The recorders are one tool among many in working out a probable cause. See how an NTSB investigation works.
The calm takeaway: black boxes exist so investigators can learn exactly what happened. What they learn goes into safety recommendations for regulators, manufacturers and airlines.
Keep reading
- How does an NTSB investigation work?
- Scared to fly after a crash in the news?
- How often are planes inspected?
- For a calm, structured week before your next trip, try 7 days to your flight, or get one plain-English explainer at a time with the free newsletter.
Quick answers
Are black boxes actually black?
No. US rules for airliners require each cockpit voice recorder container to be bright orange or bright yellow, with reflective tape and an underwater locating device, so it's easy to find.
What does a black box record?
There are two. The cockpit voice recorder captures the pilots' voices, radio calls and cockpit sounds. The flight data recorder logs measurements such as time, altitude, airspeed and heading; the NTSB says new aircraft must record at least 88 parameters.
How long do black boxes record for?
The flight data recorder keeps at least the last 25 hours of operation. Cockpit voice recorders on airliners built from May 16, 2025 must keep the last 25 hours; older ones keep at least 2 hours.
Is the cockpit audio ever made public?
No. The NTSB says Congress requires it not to release any part of the cockpit voice recording. A written transcript of the relevant parts may be released later in the investigation.
Sources
(3)
- NTSB, Cockpit Voice Recorders (CVR) and Flight Data Recorders (FDR)
- 14 CFR § 121.359, Cockpit voice recorders
- 14 CFR § 121.344, Digital flight data recorders for transport category airplanes
Facts last checked against these sources: October 19, 2026.