Abstract: Flight parameter data is real time sampled in successive sample frames and temporarily stored in memory for one or more sample frame intervals, the stored sample values are examined to detect extremes in parameter values with time, periodic ones of the temporarily stored sample frames are permanently stored in memory at fixed frame intervals notwithstanding the presence or absence of extreme values in the sample set data, sampled frames intermediate to the fixed frames are stored only in the presence of extreme sample values amoung selected ones of the sensed flight parameters.

Abstract: A communications interface exchanges serial bit signals between sources differentially, over redundant, two conductor, primary and secondary channels. The primary channel provides the communications link during normal operation, and is monitored to ensure differential operation. In response to primary channel failure, the secondary channel becomes the communications link.

Abstract: A flight data recording system includes a digital flight data recorder (DFDR) and a digital flight data acquisition unit (DFDAU) having a signal processor and nonvolatile memory for storing signals representative of a deterministic flight mode algorithm which defines a generic aircraft flight profile by preselected modes, each mode defining a flight profile operating station, the deterministic flight mode algorithm defining the nominal values of some number of sensed flight data parameters in terms of the sensed values of some number of the remaining other sensed flight parameters. At each such station, the signal processor comparing the actual sensed mandatory flight parameter value with the corresponding determined value to establish sensor accuracy.