Aviation Investigation Report A98H0003
1.11.5 Quick Access Recorder (STI1-59)
Initiatives undertaken by airlines, such as the development and implementation of increasingly complex flight operational quality assurance programs, require that an increased number of data sets be recorded. Quick access recorders (QAR) were developed because information in FDRs was not easily accessible for routine maintenance and monitoring of aircraft systems. This type of recording has been done on QARs, which are not required by regulation. Most QARs in use routinely record far more data parameters, at higher resolution and sampling rates, than do FDRs.
Unlike FDRs, QARs are not designed to survive in a crash environment. From the numerous pieces of magnetic tape recovered from the aircraft wreckage, 21 individual segments were identified as likely being from the aircraft's QAR. Attempts were made to extract information from the QAR tape; however, it was not possible to extract meaningful information from any of the pieces.
The QAR installed on SR 111 had a tape-based cartridge that recorded approximately 1 400 parameters, which is about six times the number of parameters recorded on the FDR. The additional data recorded on the QAR included numerous inputs that could have been valuable to the investigation. Such information could have assisted in determining the serviceability of aircraft systems prior to, during, and after the initial detection of the unusual smell and subsequent smoke in the cockpit.
Investigative agencies have traditionally promoted the view that additional parameters should be added to those already recorded on FDRs. Typically, the recording capacity of FDRs has not been the limiting factor; rather, these initiatives have been tempered by the high costs of installing the necessary equipment into the aircraft, including the additional data sensors and associated wiring. An additional limiting factor has been the high cost of obtaining certification for the changed mandatory FDR data set.
Modern FDRs, which employ the same solid state memory technologies as modern QARs, make it technically feasible to capture the QAR information within the FDR in a crash-protected environment. However, current regulations do not require that this be done.
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