Do Black Boxes transmit homing beacons? Or just record info?

Question

Do black boxes found on airplanes transmit signals for search parties in case of a crash? Or do they simply record data and voice information for if and when the crash site is found?

If there is some sort of beacon, how strong is the signal? Could rescue teams find it from anywhere? Or do they have to know the general area where the plane went down?

For example, if a lear jet disappeared over the Brazilian rain forest, would rescuers be able to locate the crash site from a signal from the black box?

Does anyone know how strong these signals are?

Answer 1

There are two types of "black boxes": the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR). Each recorder is equipped with an Underwater Locator Beacon (ULB) to assist in locating in the event of an overwater accident. The device called a "pinger", is activated when the recorder is immersed in water. It transmits an acoustical signal on 37.5 KHz that can be detected with a special receiver. The beacon can transmit from depths down to 14,000 feet.

For non-immersion position finding, searchers rely on the Emergency Locator Transmitter (ELT) that can be tracked by satellite as well as ground-based and aerial direction finding equipment.  The newer ones also transmit GPS coordinates. A typical ELT has about 5 watts of transmitting power.

Not all aircraft are required to carry the so-called "black boxes" (which are orange, incidentally), and the requirement for "black boxes" depends on the size and type of aircraft and how it is being used (privately or commercially).

Since all this equipment (FDR, CVR, ELT) is battery operated, the signal strengths degrade over time as the batteries lose their charge.

Answer 2

Yes, it is a transmitted Beacon signal and as long as the battery works or it is not damaged. A Beacon is a transmission signal.

A locator's receives the transmission and with the use of a omni directional antenna one can locate the transmitters beacon signal.

The beacon signal is on a international frequency set aside just for emergencies.

On a radar scope a Symbol @ will station itself automatically over the position the beacon is coming from. this symbol cannot be repositioned or dropped from the scope.

The Black box is no longer Black in color but international Orange it is located in the tail of a plane.

Another device the c**k pit recorder is located in the cockpit of the air craft  between pilot and co pilot it is a permanent fixture and can not be removed with out special tools. The c**k pit recorder, records the last 30 minutes of c**k pit conversations on a looped tape, it also records instrument reading, Engine, fuel, Air speed, Angle of Attack, Inside out side temp, Direction of heading, altitude, course, magnetic compass readings, Satellite position,and other data, Alerts etc. It as records what actions the persons in the c**k pit do in a emergency, such a flap positions, reverse engines, throttle positions, gear down, transfer fuel, dump fuel,Hydraulics locked in position and operation,nose up or down, rudder position. This is done on a multi channel recording tape, so many things can be recorded at the same time. The box is usally black and some times can be found in the nose of the aircraft.

Submarines and Naval vessles have these devices as well.

Answer 3

http://travel.howstuffworks.com/black-bo...

The typical Black Box underwater locator-beacon is for

close range detection only.

In most crash incidents they usually have a pretty good

idea where the wreckage is located as well as the

Black Box.

The added weight and cost for the system you

describe would be prohibitive for commercial

airlines.

In military aircraft the pilot or crew

are equipped with small emergency

radios that are still pretty limited

in their range.

The website above has some good info.

Answer 4

There's a cockpit voice recorder and a flight data recorder. On some aircraft there's an ELT. Emergency locator transmitter which activates in the event of impact. Some aircraft are exempt from requiring an ELT. The FAA in the US found one that was (signaling!) in the trunk of a car in the parking lot where I went to school. But sometimes a crash can destroy everything.

Answer 5

there are specialized devices for transmitting.. called ELT emergency locator. these are transmitting when exposed to the predefined G load or can be triggered manually. some also have a radio feature, i.e. they enable the operator to transmit voice.

these signals can be located much similar to the NDB locating. Their strength might be comparable to the average between the inner marker and standard radio, that means depending on the voltage remaining somewhere between 30 miles and Zero, increasing with the altitude of SAR aircraft / the one searching for the wreckage/ - the higher it flies the longer detection range.

most likely the transmission would be registered by bypassing aircrews at the 121.5 /243 MHz frequencies or via sattelite locating equipment.

for example we recently have a trouble with our elicopter landing at about 5g - it triggered the ELT, and regional rescue center was informed through the satelite warning system about incident well before the crew knew that something was wrong. the ELT transmitting on its own is kinda modem dialing voice in the radio.

some blackboxes include their own locators, but as other answerers said thesee are for short range underwater search.