Boeing 777 Mh370, Data recorders:Blackboxes

[Warhawk]

I really didn't want to go into this sad issue,.......but all really need to know the facts per Black Boxes: Per ASTB (Australia)

Crashworthiness of a FDR(Flight Data Recorder)

Flight recorders are designed to survive both high-speed impact and post-impact fire. They are, however, not invulnerable and are sometimes destroyed.

The recorder is designed to ensure that data, rather than the recorder itself, survives an accident. The data storage medium (tape or microchips) is mounted inside an impact-resistant and fire-resistant container.

Cockpit voice recorder received by the ATSB showing accident damage


The crashworthiness standards of flight recorders was revised in 2003 by the European Organisation for Civil Aviation Equipment (EUROCAE) committee, an international body on which the ATSB was represented. The recorder’s memory module is now required to withstand:

•an impact producing a 3,400-g deceleration for 6.5 milliseconds (equivalent to an impact velocity of 270 knots and a deceleration or crushing distance of 45 cm)
•a penetration force produced by a 227 kilograms (500 pounds) weight which is dropped from a height of 3 metres (10 feet)
•a static crush force of 22.25 kN (5,000 pounds) applied continuously for 5 minutes
•a fire of 1,100 degrees Celsius for 60 minutes.

The Underwater Location Beacon

Each recorder is fitted with battery-powered Underwater Location Beacon (ULB) to aid underwater recovery.

When the ULB is immersed in water, it will begin to radiate an acoustic signal which can be received and transformed into an audible signal by a receiver. The ULB is sometimes called a 'pinger' due to the audible signal created by the receiver.

Underwater Location Beacon

The ULB must meet the following requirements:

•nominal operating frequency: 37.5 kHz
•size (typical): 9.95 cm long by 3.30 cm diameter
•operating depth: 0 to 6,096 metres (20,000 feet)
•automatic activation by both fresh and salt water
•minimum operating life of 30 days. The acoustic output will decrease as the battery voltage decreases. It may be possible to still detect the ULB after 60 or more days but the detection range will be decreased.

The ULB can only be detected by a receiver under the surface of the water. The maximum detection range of a ULB is typically up to 2 to 3 kilometres but is dependent on:
•ULB acoustic output level
•receiver sensitivity
•whether the ULB is buried by debris (e.g. aircraft structure and mud)
•the ambient noise level (e.g. sea state, nearby boats, marine animals, gas and oil lines)
•water temperature gradients
•depth difference between the ULB and the receiver.

The big issue is that the Indian Ocean is really a big place and its like finding the right paddock, then searching which haystack so as to find the right needle.
Daunting.

[FONT=Impact] More can be read on: http://www.atsb.gov.au/publications/2014/b...-recorders.aspx

[Warhawk]

Crikey must be clairvoyant? Per first Specs
The ULB must meet the following requirements:

•nominal operating frequency: 37.5 kHz
•size (typical): 9.95 cm long by 3.30 cm diameter
•operating depth: 0 to 6,096 metres (20,000 feet)
•automatic activation by both fresh and salt water
•minimum operating life of 30 days. The acoustic output will decrease as the battery voltage decreases. It may be possible to still detect the ULB after 60 or more days but the detection range will be decreased.


Now China's Xinhua news agency says the "pulse signal" picked up by a black box detector on the vessel Haixun 01 had a frequency of 37.5kHz - identical to the emergency beacon signal emitted by flight recorders.

Australian Air Force planes may be sent to the southern Indian Ocean search area where the signal was recorded - about 1500km northwest of Perth.

But retired armed forces chief Angus Houston, head of Australia's search co-ordination centre, has warned there is no confirmed link to the missing Malaysia Airlines plane.

"The characteristics reported are consistent with the aircraft black box," he said in a statement.

A number of white objects were also seen on the surface about 90km from the detection area.

"However, there is no confirmation at this stage that the signals and the objects are related to the missing aircraft," he said.

Lets hope its a strong lead.

Best
Gordy