Contact|RisingUp Home

Federal Aviation Regulations

Appendix B to Part 121 — Airplane Flight Recorder Specification

ParametersRangeAccuracy sensor input to DFDR readoutSampling interval (per second)Resolution4readout
Time (GMT or Frame Counter) (range 0 to 4095, sampled 1 per frame)24 Hrs±0.125% Per Hour0.25 (1 per 4 seconds)1 sec.
Altitude−1,000 ft to max certificated altitude of aircraft±100 to ±700 ft (See Table 1, TSO-C51a)15' to 35'1
Airspeed50 KIAS to Vso, and Vsoto 1.2VD±5%, ±3%11 kt.
Normal Acceleration (Vertical)−3g to +6g±1% of max range excluding datum error of ±5%80.01g.
Pitch Attitude±75°±2°10.5°
Roll Attitude±180°±2°10.5°
Radio Transmitter KeyingOn-Off (Discrete)±2°±2%
Thrust/Power on Each EngineFull Range Forward±2°1 (per engine)0.2%2
Trailing Edge Flap or Cockpit Control SelectionFull Range or Each Discrete Position±3° or as Pilot's Indicator0.50.5%2
Leading Edge Flap or Cockpit Control SelectionFull Range or Each Discrete Position±3° or as Pilot's Indicator0.50.5%2
Thrust Reverser PositionStowed, In Transit, and Reverse (Discrete)1 (per 4 seconds per engine)
Ground Spoiler Position/Speed Brake SelectionFull Range or Each Discrete Position±2% Unless Higher Accuracy Uniquely Required10.2%2.
Marker Beacon PassageDiscrete1
Autopilot EngagementDiscrete1
Longitudinal Acceleration±1g±1.5% max range excluding datum error of ±5%40.01g.
Pilot Input and/or Surface Position—Primary Controls (Pitch, Roll, Yaw)3Full Range±2° Unless Higher Accuracy Uniquely Required10.2%2.
Lateral Acceleration±1g±1.5% max range excluding datum error of ±5%40.01g.
Pitch Trim PositionFull Range±3% Unless Higher Accuracy Uniquely Required10.3%2.
Glideslope Deviation±400 Microamps±3%10.3%2.
Localizer Deviation±400 Microamps±3%10.3%2.
AFCS Mode and Engagement StatusDiscrete1
Radio Altitude−20 ft to 2,500 ft±2 Ft or ±3% Whichever is Greater Below 500 Ft and ±5% Above 500 Ft11 ft + 5%2above 500′.
Master WarningDiscrete1
Main Gear Squat Switch StatusDiscrete1
Angle of Attack (if recorded directly).As installedAs installed20.3%2
Outside Air Temperature or Total Air Temperature.−50 °C to +90 °C±2 °c0.50.3 °c
Hydraulics, Each System Low PressureDiscrete0.5or 0.5%2
Groundspeed.As installedMost Accurate Systems Installed (IMS Equipped Aircraft Only)10.2%2
If additional recording capacity is available, recording of the following parameters is recommended. The parameters are listed in order of significance:
Drift AngleWhen available, As installedAs installed4
Wind Speed and DirectionWhen available, As installedAs installed4
Latitude and LongitudeWhen available, As installedAs installed4
Brake pressure/Brake pedal positionAs installedAs installed1
Additional engine parameters:
EPRAs installedAs installed1 (per engine).
N1As installedAs installed1 (per engine).
N2As installedAs installed1 (per engine).
EGTAs installedAs installed1 (per engine).
Throttle Lever PositionAs installedAs installed1 (per engine).
Fuel FlowAs installedAs installed1 (per engine).
TAAs installedAs installed1
RAAs installedAs installed1
Sensitivity level (as selected by crew)As installedAs installed2
GPWS (ground proximity warning system)Discrete1
Landing gear or gear selector positionDiscrete0.25 (1 per 4 seconds)
DME 1 and 2 Distance0–200 NM;As installed0.251 mi.
Nav 1 and 2 Frequency SelectionFull rangeAs installed0.25

1When altitude rate is recorded. Altitude rate must have sufficient resolution and sampling to permit the derivation of altitude to 5 feet.

2Per cent of full range.

3For airplanes that can demonstrate the capability of deriving either the control input on control movement (one from the other) for all modes of operation and flight regimes, the “or” applies. For airplanes with non-mechanical control systems (fly-by-wire) the “and” applies. In airplanes with split surfaces, suitable combination of inputs is acceptable in lieu of recording each surface separately.

4This column applies to aircraft manufactured after October 11, 1991.

[Doc. No. 25530, 53 FR 26147, July 11, 1988; 53 FR 30906, Aug. 16, 1988]

NEXT: Appendix C to Part 121 - C–46 Nontransport Category Airplanes
PREVIOUS: Appendix A to Part 121 - First Aid Kits and Emergency Medical Kits

Search the FARS for