Smaller Flight Data Recorders

Journal of Aviation Technology and Engineering, Mar 2013

Data captured by flight data recorders are generally stored on the system’s embedded hard disk. A common problem is the lack of storage space on the disk. This lack of space for data storage leads to either a constant effort to reduce the space used by data, or to increased costs due to acquisition of additional space, which is not always possible. File compression can solve the problem, but carries with it the potential drawback of the increased overhead required when writing the data to the disk, putting an excessive load on the system and degrading system performance. The author suggests the use of an efficient compressed file system that both compresses data in real time and ensures that there will be minimal impact on the performance of other tasks.

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Smaller Flight Data Recorders

Journal of Aviation Technology and Engineering Smaller Flight Data Recorders{ Yair Wiseman 0 1 Alon Barkai 0 1 Bar-Ilan University 0 Mr. Alon Barkai completed an MSc of Computer Science at Bar-Ilan University. Mr. Barkai is the Founder and CEO of Ziroon Ltd 1 Dr. Yair Wiseman was a postdoctoral scholar at the Georgia Institute of Technology in conjunction with Delta Air Lines, Inc. He is now with Bar-Ilan , USA Data captured by flight data recorders are generally stored on the system's embedded hard disk. A common problem is the lack of storage space on the disk. This lack of space for data storage leads to either a constant effort to reduce the space used by data, or to increased costs due to acquisition of additional space, which is not always possible. File compression can solve the problem, but carries with it the potential drawback of the increased overhead required when writing the data to the disk, putting an excessive load on the system and degrading system performance. The author suggests the use of an efficient compressed file system that both compresses data in real time and ensures that there will be minimal impact on the performance of other tasks. flight data recorder; data compression; file system Introduction About the Author record thousands of parameters for hundreds of flight hours in flight data recorders or quick access recorders is now possible. Compression algorithms are used by the manufacturers and may become even more prevalent with the introduction of video recorders. New video compression schemes have a significant compression factor which is usually some hundreds of times; that is, the compressed file will be less than 1% of the size of original file (Horowitz et al., 2012) . This means that the compression is still useful, even though the memory capacity is much larger. This work has been done relative to hard disks of flight data recorders, but flash memory developers can utilize the results, as well. An ordinary difficulty is that flight data recorders run out of space on hard disks. The concern of encountering this difficulty leads one to act cautiously, constantly attempting to reduce the used data space (Wu, Banachowski, & Brandt, 2005) . In addition, working with nearly full disks causes the allocation of new file blocks to be distributed across multiple platters. Working with files scattered around the hard disk drive is slow and very demanding on the read/write head, with unnecessary overhead (Ng, 1998) . However, unlike flight data recorders, in regular desktops the vast majority of disks are not overloaded and so it is better to keep old versions of important files on the disk even though, in most cases, one will not use the old versions (Muniswamy-Reddy, Wright, Himmer, & Zadok, 2004) . Data are often processed by embedded systems. In the embedded computing world and especially in flight data recorders, it is clear that the storage problem is significant, as the storage area is hundreds of times less than the storage space available on desktop computers. In a common embedded computer system there is an electronic card with a simple processor that supports a small solid state device which provides barely 1 to 4 GB of space for the system files. Usually it is not possible to add additional storage space such as a hard disk drive or even SD reader because of hardware constraints, system constraints, size constraints, and power consumption constraints (Yaghmour, Masters, Gerum, & Ben-Yossef, 2008) . A photograph of a flight data recorder’s storage device can be seen in Figure 2. It is difficult to install a full operating system environment which includes a compilation chain (Tool Chain) and GUI (X Server) in such a small storage space. For the purpose of illustration, a basic installation of a Gentoo Linux distribution with a command line user interface, a stage-3 compilation tool chain, and its Portage package manager, without any graphical interface or other packages, occupies 1.5 GB. The easiest solution to this problem is removing features, installing only the essentials, and developing lighter applications for the embedded cards of flight data recorders. More profitable solutions include the use of disk data compression (Benini, Bruni, Macii, & Macii., 2002; Roy, Kumar, & Prvulovic, 2001) . Other devices can use compression of rarely-used data, or compression of all data, and expansion only of data needed in run time; but flight data recorders can assume all the data is rarely-used. Compressing the data will directly yield more storage space without losing any information. However, this has a serious impact on system performance, especially when a relatively small process is located on the same electronic card that needs to simultaneously compress the file being written to the disk while continuing running the other applications without compromising them. For this reason, embedded developers usually do not use file system compression in orde (...truncated)


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Yair Wiseman, Alon Barkai. Smaller Flight Data Recorders, Journal of Aviation Technology and Engineering, 2013, Volume 2, Issue 2,