Part 121: Appendix B - Instruments and Equipment Airworthiness Design Standards

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Instruments and equipment required by Subpart F must meet the following
specifications and requirements:

B.1 Protective breathing equipment

(a) Protective breathing equipment must—

(1) meet the requirements of the TSO C99 series or the TSO C116 series; and

(2) provide a breathing gas system that is free from hazards in—

(i) itself; and

(ii) its method of operation; and

(iii) its effect upon other components; and

(3) provide protection for the eyes without unduly restricting vision; and

(4) allow any crew member to—

(i) determine during flight the quantity of breathing gas available in each source of supply unless the gas system uses chemical oxygen generators; and

(ii) use corrective glasses without undue impairment of vision, or loss of protection; and

(iii) communicate using the crew member intercom system; and

(5) allow the flight crew members to communicate using the aeroplane radios; and

(6) supply breathing gas for 15 minutes at a pressure altitude of 8 000 feet.

(b) Protective breathing equipment may also be used to meet the supplemental oxygen requirements of Part 91 provided it meets the oxygen equipment standards.

B.2 Emergency medical kit

Emergency medical kits must—

(1) be located and secured such that—

(i) the possibility of damage or loss as the result of an accident is minimised; and

(ii) there is no danger to the occupants of the aeroplane; and

(2) have their location marked on the outside of any compartment containing the kit; and

(3) be marked for use by qualified medical personnel only; and

(4) when containing narcotics, be installed in an aeroplane that—

(i) meets the requirements of the Misuse of Drugs Regulations 1977; and

(ii) when not in use can be locked, or placed in a lockable hangar, or have the first aid kit containing narcotics removed to a safe and secure location.

B.3 Public address system

(a) A public address system must—

(1) except for handsets, headsets, microphones, selector switches, and signalling devices, be capable of operation independent of the crew member intercom system required by rule 121.369(2); and

(2) be accessible for immediate use from each of two flight crew member stations in the flight crew compartment; and

(3) for each required floor-level passenger emergency exit that has an adjacent flight attendant seat, have a microphone which is readily accessible to the seated flight attendant; and

(4) be capable of operation within 10 seconds by a flight attendant at each of those stations in the passenger compartment from which its use is accessible; and

(5) be understandably audible at all times at all passenger seats, lavatories, flight attendant seats, and work stations.

(b) For the purposes of paragraph (a)(3) one microphone may serve more than one exit, provided the proximity of the exits allows unassisted verbal communication between seated flight attendants.

B.4 Crew member intercom system

A crew-member intercom system must—

(1) except for handsets, headsets, microphones, selector switches, and signalling devices, be capable of operation independent of the public address system required by rule 121.369(1); and

(2) provide a means of two-way communication between all members of the flight crew; and

(3) provide a means of two-way communication between the flight crew compartment and each passenger compartment; and

(4) be accessible for immediate use from each of two flight crew member stations in the flight crew compartment; and

(5) be accessible for use from at least one normal flight-attendant station in each passenger compartment; and

(6) be capable of operation within 10 seconds by a flight attendant at each of those stations in each passenger compartment from which its use is accessible; and

(7) be accessible for use at enough flight attendant stations so that all floor-level emergency exits in each passenger compartment are observable from a station so equipped; and

(8) have an alerting system that—

(i) incorporates aural or visual signals for use by any crew member; and

(ii) has a means for the recipient of a call to determine whether it is a normal call or an emergency call; and

(9) provide a means of two-way communication between ground personnel and any two flight crew members in the flight crew compartment—

(i) when the aeroplane is on the ground; and

(ii) from a location that avoids visible detection from within the aeroplane during the operation of the ground personnel intercom system station.

B.5 Cockpit voice recorder

A cockpit voice recorder must —

(1) meet the requirements of the TSO C123 series; and

(2) be fitted with an underwater locating device that meets the requirements of the TSO C121 series; and

(3) record and stores at least the last 2 hours of its operation; and

(4) have an alternate power source that is separate from the power source that normally provides power to the recorder and complies with standard 6.3.2.4.1 of ICAO Annex 6.

B.6 Flight data recorder

A flight data recorder must —

(1) meet the requirements of the TSO C124 series; and

(2) be fitted with an underwater locating device that meets the requirements of the TSO C121 series; and

(3) be of a non-ejectable type and capable of recording and storing at least the last 25 hours of its operation in a digital form; and

(4) record the parameters as detailed in—

(i) Figure 1; and

(ii) as applicable, Table 1 and Table 2—

of Appendix B.

B.7 Additional attitude indicator

The third presentation of attitude must be—

(1) operated independently of any other attitude indicating system; and

(2) powered from a source independent of the electrical generating system; and

(3) capable of continuous reliable operation for 30 minutes after total failure of the electrical generating system; and

(4) operative without selection after total failure of the electrical generating system; and

(5) appropriately lighted during all phases of operation.

B.8 Weather radar

Weather radar must meet the requirements of the TSO C63 series.

B.9 Ground proximity warning system

GPWS must meet the requirements of the TSO C92 series.

B.10 Terrain awareness and warning system (TAWS)

TAWS Class A must meet the requirements of TSO C151a or TSO C151b for Class A equipment.

TAWS Class B must meet the requirements of TSO C151a or TSO C151b for Class B equipment.

B.11 Airborne Collision Avoidance System (ACAS II)

ACAS II must meet the requirements of TSO C119b.

Figure 1. Flight Data Recorder Decision Chart

Notes

1. General Dynamics Convair 580, 600, 640, deHavilland Aircraft Company Ltd. DHC- 7, Fairchild Industries FH 227, Fokker F-27 (except Mark 50), F-28 Mark 1000 and Mark 4000, Gulfstream Aerospace G-159, Lockheed Aircraft Corporation Electra 10- A, 10-B, 10-E, L-188, Maryland Air Industries, Inc. F27, Mitsubishi Heavy Industries, Ltd. YS-11, Short Bros. Limited SD3-30, SD3-60.

2. Parameters 12 through 17 may be recorded from a single source.

3. Parameters 12 through 14 may be recorded from a single source.

Table 1. Part 121 - Flight Data Recorder Parameter Requirements

When reading the parameter specifications from Table 2 the corresponding shaded specification should be chosen for each parameter. This table refers to the FDR requirements of rule 121.373.

Table 1 PDF version [PDF 574 KB]

Parameters * if installed	6 Parameter	11 Parameter	17 Parameter	44 Parameter	88 Parameter
	(A)	(B)	(C)	(D)	(E)
1	Time	Time	Time	Time	Time or Relative time counts
2	Altitude	Altitude	Altitude	Altitude	Pressure Altitude
3	Airspeed	Airspeed	Airspeed	Airspeed	Indicated airspeed or Calibrated airspeed
4	Vertical acceleration	Vertical acceleration	Vertical acceleration	Heading	Heading (primary flight crew reference)
5	Heading	Heading	Heading	Vertical acceleration	Normal acceleration (vertical)
6	Time of radio transmission to/from ATC	Time of radio transmission to/from ATC	Time of radio transmission to/from ATC	Pitch attitude	Pitch attitude
7		Pitch attitude	Pitch attitude	Roll attitude	Roll attitude
8		Roll attitude	Roll attitude	Radio transmitter keying	Manual radio transmitter keying or CVR/DFDR synchronization reference
9		Longitudinal acceleration	Longitudinal acceleration	Thrust/power on each engine	Thrust/power on each engine (primary flight crew reference)
10		Control column OR pitch control surface position	Pitch trim position	Trailing edge flap OR cockpit control selection	Autopilot engagement
11		Thrust of each engine	Control column OR pitch control surface position	Leading edge flap OR cockpit control selection	Longitudinal acceleration
12			Control wheel OR lateral control surface position	Thrust reverser position	Pitch control(s) position (non flyby- wire systems)
12			Control wheel OR lateral control surface position	Thrust reverser position	Pitch control(s) position (non flyby- wire systems)
13			Rudder pedal OR yaw control surface position	Ground spoiler position/speed brake selection	Lateral control(s) position (non fly-by-wire systems)
13			Rudder pedal OR yaw control surface position	Ground spoiler position/speed brake selection	Lateral control(s) position (fly-by-wire systems)
14			Thrust of each engine	Marker beacon passage	Yaw control(s) position (non fly-by- wire systems)
14			Thrust of each engine	Marker beacon passage	Yaw control(s) position (non fly-by- wire systems)
15			Position of each thrust reverser	Autopilot engagement	Pitch control surface(s) position
16			Pitch control surface(s) position	Longitudinal acceleration	Lateral control surface(s) position
17			Leading edge flap OR cockpit flap control position	Pilot input and/or surface position - primary controls	Yaw control surface(s) position
18				Lateral acceleration	Lateral acceleration
19				Pitch trim position	Pitch trim surface position
20				Glideslope deviation	Trailing edge flap or cockpit control position
21				Localiser deviation	Leading edge flap or cockpit control position
22				AFCS mode and engagement status	Each thrust reverser position or equivalent for propeller aeroplane
23				Radio altitude	Ground spoiler position or speed brake position
24				Radio altitude	Outside air temperature or total air temperature
25				Main gear squat switch status	Autopilot/ autothrottle/AFC S mode and engagement status
26				Angle of attack	Radio altitude
27				Outside air temperature OR total air temperature	Localiser deviation or MLS azimuth
28				Hydraulics, each system, low pressure	Glideslope deviation or MLS elevation
29				Groundspeed	Marker beacon passage
30				Drift angle	Master warning
31				Wind speed and direction	Air/ground sensor (primary aeroplane sensor, nose or main gear)
32				Latitude and longitude	Angle of attack (if measure directly)
33				Brake pressure/pedal position	Brake pressure/pedal position
34				Additional engine parameters: EPR, N1, N2	Groundspeed
35				Exhaust Gas Temperature	GPWS
36				Throttle lever position	Landing gear position or landing gear cockpit control selection
37 *				Fuel flow	Drift angle
38 *				TCAS - TA	Wind speed and direction
39 *				TCAS - TA	Latitude and longitude
40 *				TCAS - Sensitivity level	TCAS - Sensitivity level
41 *				Ground Proximity Warning System	Windshear detection
42				Landing gear or gear selector position	Throttle/power lever position
43				DME 1 and 2 distance	Additional engine parameters
44				Nav 1 and 2 frequency selection	TCAS
45					DME 1 and 2 distances
46					Nav 1 and 2 selected frequency
47 *					Selected barometric setting
48 *					Selected altitude
49 *					Selected speed
50 *					Selected Mach
51 *					Selected vertical speed
52 *					Selected heading
53 *					Selected flight path
54 *					Selected decision height
55					EFIS display format
56					Multifunction/ engine alerts display format
57 *					Thrust command
58 *					Thrust target
59 *					Fuel quantity in CG trim tank
60					Primary navigation system reference
61 *					Ice detection
62 *					Engine warning each engine - vibration
63 *					Engine warning each engine - over temp
64 *					Engine warning each engine - oil pressure low
65 *					Engine warning each engine - over speed
66					Yaw trim surface position
67					Roll trim surface position
68					Brake pressure - left and right
69					Brake pedal application - left and right
70 *					Yaw and side-slip angle
71 *					Engine bleed valve position
72 *					De-icing or antiicing system selection
73 *					Computed centre of gravity
74 *					AC electrical bus status
75					AC electrical bus status
76 *					APU bleed valve position
77					Hydraulic pressure each system
78					Loss of cabin pressure
79					Computer failure - critical flight and engine control systems
80 *					HUD
81 *					Para-visual display
82					Cockpit trim control input position - pitch
83					Cockpit trim control input position - roll
84					Cockpit trim control input position - yaw
85					Trailing edge flap and cockpit flap control position
86					Leading edge flap and cockpit flap control position
87					Ground spoiler position and speed brake selection
88					All cockpit flight control input forces - control wheel, control column, rudder pedal

Table 2. Part 121 - Flight Data Recorder Parameter Specifications.

This table refers to the FDR requirements of rule 121.373.

Table 2 PDF version [PDF 481 KB]

Parameters	Range	Sensor input accuracy	Seconds per sampling interval	Resolution	Remarks
Time or Relative time counts	24 hours 0 to 4095	±0.125% per hour	4	1s	UTC time preferred when available. Counter increments each four seconds of system operation
Pressure Altitude	-1000’ to maximum certificated altitude -1000’ to maximum certificated altitude +5000’	±100’ to ±700’ (refer TSO C124a, C51a)	1	5’ to 35’	Data should be obtained from the air data computer when practicable
Indicated airspeed or Calibrated airspeed	50 KIAS or minimum value to Max Vso, and Vso to 1.2VD	±5% and ±3%	1	1kt	Data should be obtained from the air data computer when practicable
Heading (primary flight crew reference)	0 - 360º 0 - 360º and discrete ‘true’ or ‘mag’	±2º	1	0.5º	When true or magnetic heading can be selected as the primary heading reference, a discrete indicating selection must be recorded
Normal acceleration (vertical)	-3g to +6g	±1% maximum range excluding datum error of ±5%	0.125	0.004g
Pitch attitude	±75º	±2º	1 or 0.25 for aeroplanes manufactured after 2002	0.5º	A sampling rate of 0.25 is recommended
Roll attitude	±180º	±2º	1 or 0.5 for aeroplanes manufactured after 2002	0.5º	A sampling rate of 0.5 is recommended
Manual radio transmitter keying or CVR/DFDR synchronisation reference	Discrete - ‘on’ or ‘off’		1		Preferably each crew member but one discrete acceptable for all transmission provided the CVR/DFDR system complies with TSO C124a CVR synchronisation requirements
Thrust/power on each engine (primary flight crew reference)	Full range forward	±2%	1 per engine	0.3% of full range	Sufficient parameters (e.g. EPR, N1 or Torque, NP) as appropriate to the particular engine be recorded to determine power in forward and reverse thrust, including potential overspeed conditions
Autopilot engagement	Discrete - ‘on’ or ‘off’		1
Longitudinal acceleration	±1g	±1.5% maximum range excluding datum error of ±5%	0.25	0.004 g
Pitch control(s) position (non fly-by-wire systems)1	Full range	±2º	1 0.5 or 0.25 for aeroplanes manufactured after 2002	0.5% of full range	For aeroplanes that have a flight control break away capability that allows either pilot to operate the controls independently, record both control inputs. The control inputs may be sampled alternately once per second to produce the sampling interval of 0.5 or 0.25, as applicable
Pitch control(s) position (fly-by-wire systems)	Full range	±2º	1 0.5 or 0.25 for aeroplanes manufactured after 2002	0.275% of full range
Lateral control(s) position (non fly-by-wire systems)1	Full range	±2º	1 0.5 or 0.25 for aeroplanes manufactured after 2002	0.2% of full range	For aeroplanes that have a flight control break away capability that allows either pilot to operate the controls independently, record both control inputs. The control inputs may be sampled alternately once per second to produce the sampling interval of 0.5 or 0.25, as applicable
Lateral control(s) position (fly-by-wire systems)	Full range	±2º	1 0.5 or 0.25 for aeroplanes manufactured after 2002	0.22% of full range
Yaw control(s) position (non fly-by-wire systems)1	Full range	±2º	1 0.5	0.3% of full range	For aeroplanes that have a flight control break away capability that allows either pilot to operate the controls independently, record both control inputs. The control inputs may be sampled alternately once per second to produce the sampling interval of 0.5
Yaw control(s) position (flyby- wire systems)	Full range	±2º	1 0.5	0.2% of full range
Pitch control surface(s) position1	Full range	±2º	1 0.5 or 0.25 for aeroplanes manufactured after 2002	0.2% of full range	For aeroplanes fitted with multiple or split surfaces, a suitable combination of inputs is acceptable in lieu of recording each surface separately. The control surfaces may be sampled alternately to produce the sampling interval of 0.5 or 0.25
Lateral control surface(s) position1	Full range	±2º	1 0.5 or 0.25 for aeroplanes manufactured after 2002	0.3% of full range	For aeroplanes fitted with multiple or split surfaces, a suitable combination of surface position sensors is acceptable in lieu of recording each surface separately. The control surfaces may be sampled alternately to produce the sampling interval of 0.5 or 0.25
Yaw control surface(s) position1	Full range	±2º	1 0.5	0.2% of full range	For aeroplanes fitted with multiple or split surfaces, a suitable combination of surface position sensors is acceptable in lieu of recording each surface separately. The control surfaces may be sampled alternately to produce the sampling interval of 0.5
Lateral acceleration	±1g	±1.5% maximum range excluding datum error of ±5%	0.25	0.004g	Twin engine aircraft only
Pitch trim surface position	Full range	±3%	1	0.6% of full range
Trailing edge flap or cockpit control position	Full range or discrete each position	±3º or pilot’s indicator	2	0.5% of full range	Flap position and cockpit control may each be sampled alternately at four second intervals, to give a data point every two seconds
Leading edge flap or cockpit control position	Full range or discrete each position	±3º or pilot’s indicator	2	0.5% of full range	Left and right sides, or flap position and cockpit control may each be sampled at four second intervals, so as to give a data point each two seconds
Each thrust reverser position or equivalent for propeller aeroplane	Discrete - ‘stowed’, ‘in transit’, ‘reverse’		1 per engine		Turbojet - two discretes enable the three states to be determined Turboprop - one discrete
Ground spoiler position or speed brake position	Full range or discrete each position	±2º	1 or 0.5 for aeroplanes manufactured after 2002	0.5% of full range
Outside air temperature or total air temperature	-50ºC to +90ºC	±2º C	2	0.3º C
Autopilot/ autothrottle/ AFCS mode and engagement status	Discretes - suitable combination		1		Discretes should show which systems are engaged and which primary modes are controlling the flight path and speed of the aircraft
Radio altitude	-20’ to +2 500’	±2’ or ±3% whichever is the greater below 500’ and ±5% above 500’	1	1’ + 5% above 500’	For autoland/ category III operations, each radio altimeter should be recorded, but arranged so that at least one is recorded each second.
For autoland/ category III operations, each radio altimeter should be recorded, but arranged so that at least one is recorded each second.	±400 microamps or available sensor range as installed ±62º	As installed - ±3% recommended	1	0.3% of full range	For autoland/ category III operations, each radio altimeter should be recorded, but arranged so that at least one is recorded each second. It is not necessary to record ILS and MLS at the same time, only the approach aid in use need be recorded
Glideslope deviation, MLS elevation, or GNSS vertical deviation.	±400 microamps or available sensor range as installed +0.9º to +30º	As installed - ±3% recommended	1	0.3% of full range	For autoland/ category III operations, each radio altimeter should be recorded, but arranged so that at least one is recorded each second. It is not necessary to record ILS and MLS at the same time, only the approach aid in use need be recorded
Marker beacon passage	Discrete - 'on' or 'off'		1		A single discrete is acceptable for all markers
Master warning	Discrete		1		Record the master warning and record each 'red' warning that cannot be determined from other parameters or from the cockpit voice recorder
Air/ground sensor (primary aeroplane sensor, nose or main gear)	Discrete - ‘air’ or 'ground'		1 (0.25 recommended)
Angle of attack (if measure directly)	As installed	As installed	2 or 0.5 for aeroplanes manufactured after 2002	0.3% of full range	If left and right sensors are available, each may be recorded at four second intervals so as to give a data point each 0.5 second
Hydraulic pressure low, each system	Discrete - ‘low’ or ‘normal’ or available sensor range	±5%	2	0.5% of full range
Groundspeed	As installed	Most accurate system installed	1	0.2% of full range
GPWS	Discrete - 'warning' or 'off'		1		A suitable combination of discretes unless recorder capacity is limited in which case a single discrete for all modes is acceptable
Landing gear position or landing gear cockpit control selection	Discrete		4		A suitable combination of discretes should be recorded
Drift angle	As installed	As installed	4	0.1º
Wind speed and direction	As installed	As installed	4	1kt and 1º
Latitude and longitude	As installed	As installed	4	0.002º	Provided by the Primary Navigation System Reference. Where capacity permits latitude/longitude resolution should be 0.0002º
Stick shaker and pusher activation	Discrete - 'on' or 'off'		1		A suitable combination of discretes to determine activation
Windshear detection	Discrete - 'warning' or 'off'		1
Throttle/power lever position	As installed Full range	As installed ±2%	1 per lever	2% of full range	For aeroplanes with nonmechanically linked cockpit engine controls
Additional engine parameters	As installed	As installed	Each engine each second	2% of full range	EPR, N1, N2, EGT Where capacity permits, the preferred priority is - indicated vibration level, N2, EGT, Fuel Flow, Fuel Cutoff lever position, and N3, unless the engine manufacturer recommends otherwise
TCAS	Discretes	As installed	1		A suitable combination of discretes should be recorded to determine the status of - Combined Control, Vertical Control, Up Advisory, and Down Advisory. (refer ARINC Characteristic 735 - Attachment 6E, TCAS VERTICAL RA DATA OUTPUT WORD)
DME 1 and 2 distances	0 - 200NM	As installed	4	1NM	1 mile
Nav 1 and 2 selected frequency	Full range	As installed	4		Sufficient to determine selected frequency
Selected barometric setting	Full range	±5%	1 per 64 seconds	0.2% of full range
Selected altitude	Full range	±5%	1	100’
Selected speed	Full range	±5%	1	kt
Selected Mach	Full range	±5%	1	0.01
Selected vertical speed	Full range	±5%	1	100ft/min
Selected heading	Full range	±5%	1	1º
Selected flight path	Full range	±5%	1	1º
Selected decision height	Full range	±5%	64	1’
EFIS display format	Discretes		4		Discretes should show the display system status (off, normal, fail, composite, sector, plan, navigation aids, weather radar, range, copy)
Multi-function/engine alerts display format	Discretes		4		Discretes should show the display system status (off, normal, fail) and the identity of display pages for emergency procedures need not be recorded
Thrust command	Full range	±2%	2	2% of full range
Thrust target	Full range	±2%	4	2% of full range
Fuel quantity in CG trim tank	Full range	±5%	1 per 64 seconds	1% of full range
Primary navigation system reference	Discretes - ‘GNSS’, ‘INS’, ‘VOR/DME’, ‘MLS’, ‘Loran C’, ‘Omega’, ‘Localiser Glideslope’		4		A suitable combination of discretes to determine the Primary Navigation System reference
Ice detection	Discrete - ‘ice’ or ‘no ice’		4
Engine warning each engine - vibration	Discrete		1
Engine warning each engine - over temp	Discrete		1
Engine warning each engine - oil pressure low	Discrete		1
Engine warning each engine - over speed	Discrete		1
Yaw trim surface position	Full range	±3%	2	0.3% of full range
Roll trim surface position	Full range	±3%	2	0.3% of full range
Brake pressure - left and right	As installed	As installed ±5%	1		To determine braking effort applied by pilots or by autobrakes
Brake pedal application - left and right	Discrete or analogue - ‘applied’ or ‘off’	As installed ±5%	1		To determine braking applied by pilots
Yaw and side-slip angle	Full range	±5%	1	0.5º
Engine bleed valve position	Discrete - ‘open’ or ‘closed’		4
De-icing or anti-icing system selection	Discrete - 'on' or 'off'		4
Computed centre of gravity	Full range	±5%	1 per 64 seconds	1% of full range
AC electrical bus status	Discrete - 'power' or 'off'		4		Each bus
DC electrical bus status	Discrete - 'power' or 'off'		4		Each bus
APU bleed valve position	Discrete - ‘open’ or ‘closed’		4
Hydraulic pressure each system	Full range	±5%	2	100psi
Loss of cabin pressure	Discrete - ‘loss’ or ‘normal’		1
Computer failure - critical flight and engine control systems	Discrete - ‘fail’ or ‘normal’		4
HUD	Discrete - 'on' or 'off'		4
Para-visual display	Discrete - 'on' or 'off'		1
Cockpit trim control input position - pitch	Full range	±5%	1	0.2% of full range	Where mechanical means for control inputs are not available, cockpit display trim positions should be recorded.
Cockpit trim control input position - roll	Full range	±5%	1	0.7% of full range	Where mechanical means for control inputs are not available, cockpit display trim positions should be recorded.
Cockpit trim control input position - yaw	Full range	±5%	1	0.3% of full range	Where mechanical means for control inputs are not available, cockpit display trim positions should be recorded.
Trailing edge flap and cockpit flap control position	Full range or discrete each position	±5%	2	0.5% of full range	Trailing edge flaps and cockpit flap control position may each be sampled alternately at four second intervals to provide a sample each 0.5 second
Leading edge flap and cockpit flap control position	Full range or discrete each position	±5%	1	0.5% of full range
Ground spoiler position and speed brake selection	Full range or discrete each position	±5%	0.5	0.3%of full range
All cockpit flight control input forces - control wheel, control column, rudder pedal	Full range – control wheel- ±70lbs, control column ±85lbs, rudder pedals, ±165lbs.	±5%	1	0.3%of full range	For fly-by-wire flight control systems, where flight control surface position is a function of the displacement of the control input device only, it is not necessary to record this parameter

Notes:

1. For aeroplanes that can demonstrate the capability of deriving either the control input or control movement (one from the other) for all modes of operation and flight regimes only the surface position OR the control position need be sensed. For aeroplanes with non-mechanical control systems (fly-by-wire) both surface and control position must be recorded.

Subpart N

Appendix C