Flight data recorders: filtered data

This regulation controls how flight data recorder (FDR) signals can be processed before recording. "Filtering" means altering the original sensor signal in ways beyond basic digital conversion, formatting, or removing frequencies outside the sensor's range.

Airlines may only filter required FDR parameters if the recorded data still meets accuracy standards in the regulation's appendices. For critical parameters like pitch, roll, and control positions, if filtering causes the data to fall short of these standards, operators must either remove the filtering or prove they can reconstruct the original sensor values from the filtered data—a process requiring FAA approval.

This matters because accident investigators rely on precise FDR data. Excessive filtering could mask important flight characteristics or control inputs. The regulation established deadlines (2011-2014) for airlines to identify filtered parameters, remove problematic filtering, or obtain FAA approval for reconstruction procedures. All documentation must be maintained as part of the aircraft's FDR correlation records.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*