14 CFR · Part 135
14 CFR Part 135, Appendix B
Airplane Flight Recorder Specifications
| Parameters | Range | Installed system ¹ minimum accuracy (to recovered data) | Sampling interval (per second) | Resolution ⁴ read out |
|---|---|---|---|---|
| Relative time (from recorded on prior to takeoff) | 25 hr minimum | ±0.125% per hour | 1 | 1 sec. |
| Indicated airspeed | Vso to VD (KIAS) | ±5% or ±10 kts., whichever is greater. Resolution 2 kts. below 175 KIAS | 1 | 1% ³. |
| Altitude | −1,000 ft. to max cert. alt. of A/C | ±100 to ±700 ft. (see Table 1, TSO C51-a) | 1 | 25 to 150 |
| Magnetic heading | 360° | ±5° | 1 | 1° |
| Vertical acceleration | −3g to + 6g | ±0.2g in addition to ±0.3g maximum datum | 4 (or 1 per second where peaks, ref. to 1g are recorded) | 0.03g. |
| Longitudinal acceleration | ±1.0g | ±1.5% max. range excluding datum error of ±5% | 2 | 0.01g. |
| Pitch attitude | 100% of usable | ±2° | 1 | 0.8° |
| Roll attitude | ±60° or 100% of usable range, whichever is greater | ±2° | 1 | 0.8° |
| Stabilizer trim position | Full range | ±3% unless higher uniquely required | 1 | 1% ³. |
| Or | ||||
| Pitch control position | Full range | ±3% unless higher uniquely required | 1 | 1% ³. |
| Engine Power, Each Engine | ||||
| Fan or N₁ speed or EPR or cockpit indications used for aircraft certification | Maximum range | ±5% | 1 | 1% ³. |
| Or | ||||
| Prop. speed and torque (sample once/sec as close together as practicable) | 1 (prop speed), 1 (torque) | |||
| Altitude rate ² (need depends on altitude resolution) | ±8,000 fpm | ±10%. Resolution 250 fpm below 12,000 ft. indicated | 1 | 250 fpm Below 12,000 |
| Angle of attack ² (need depends on altitude resolution) | −20° to 40° or of usable range | ±2° | 1 | 0.8% ³ |
| Radio transmitter keying (discrete) | On/off | 1 | ||
| TE flaps (discrete or analog) | Each discrete position (U, D, T/O, AAP) | 1 | ||
| Or | ||||
| Analog 0-100% range | ±3° | 1 | 1% ³ | |
| LE flaps (discrete or analog) | Each discrete position (U, D, T/O, AAP) | 1 | ||
| Or | ||||
| Analog 0-100% range | ±3° | 1 | 1% ³. | |
| Thrust reverser, each engine (Discrete) | Stowed or full reverse | 1 | ||
| Spoiler/speedbrake (discrete) | Stowed or out | 1 | ||
| Autopilot engaged (discrete) | Engaged or disengaged | 1 |
¹ When data sources are aircraft instruments (except altimeters) of acceptable quality to fly the aircraft the recording system excluding these sensors (but including all other characteristics of the recording system) shall contribute no more than half of the values in this column. ² If data from the altitude encoding altimeter (100 ft. resolution) is used, then either one of these parameters should also be recorded. If however, altitude is recorded at a minimum resolution of 25 feet, then these two parameters can be omitted. ³ Per cent of full range. ⁴ This column applies to aircraft manufacturing after October 11, 1991.
Reflects the eCFR edition current as of September 29, 2026. Retrieved from ecfr.gov on October 16, 2026.
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