Format Case

The QARs obtain information from a range of sensors throughout the plane across thousands of parameters, although not all of those parameters are analysed on a regular basis. The data is recorded on a flash memory card or similar. The format that the data is in is up to the system designer, however many systems use the Harvard bi-phase format.

The format that information is recorded on a DFDR using stolid state technology can be up to 256 12-bit data words per second, which is four times the capacity of the old magnetic tape DFDRs.

If a Signal Directory was being submitted to CASA for a new aircraft type all parameters would need to be in place according to satisfy the requirements. This would include a Lateral Acceleration parameter, which would need to record at a rate of one frame per second, including 4 sub frames to satisfy CAO 103.19, which states that the maximum recording interval is to be 0.25 seconds.

The event button is designed so that the crew can show an indication that an 'event' was noticed. An event may be anything that was not expected by the crew that is outside of normal operating conditions. It will allow investigators to easily find the section of the DFDR when the crew first noticed the problem. The lack of the crew pressing this problem also indicates to the crew if they were unaware of the problem or too busy to respond.

Some of the parameters that have been recorded on a DFDR can be represented in analogue format. This can be presented in a graph, when the graph is changing it is equivalent to a one in digital format, and when the graph was stagnant that is a zero in digital format. The diagram shown represents 1010.

The advances in aircraft flight data recorders have allowed an increased amount of vital information to be recovered in aircraft accidents. This information is invaluable as it plays a major role in the subsequent investigations and conclusions that can be drawn from these accidents, which then allow the same mistakes not to be made again. The advent of eQARs has also allowed airlines to monitor every flight like never before allowing improvements to safety and efficiency.

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