ASTM F3233/F3233M-23a

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F3233/F3233M − 23 F3233/F3233M − 23a
Standard Specification for
Flight and Navigation Instrumentation in Aircraft
This standard is issued under the fixed designation F3233/F3233M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers flight and navigation instrumentation aspects of airworthiness and design. The material was
developed through open consensus of international experts in general aviation. This information was created by focusing on Level
1, 2, 3, and 4 Normal Category aeroplanes; however, the content may be more broadly applicable, and should not be unduly
limited. The topics covered within this specification are flight and navigation instruments including those for airspeed, altitude,
attitude, heading, free air temperature, and speed warning.
1.2 The applicant for a design approval shall seek the individual guidance of their respective CAA body concerning the use of this
specification as part of a certification plan. For information on which CAA regulatory bodies have accepted this specification (in
whole or in part) as a means of compliance to their Small Aircraft Airworthiness regulations (hereinafter referred to as “the Rules”),
refer to ASTM F44 webpage (www.ASTM.org/COMMITTEE/F44.htm), which includes CAA website links. Annex A1 maps the
means of compliance described in this specification to EASA CS 23, amendment 5 or later, and FAA 14 CFR 23, amendment 64
or later.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 Following is a list of external standards reference throughout this specification; the earliest revision acceptable for use is
indicated. In all cases, later document revisions are acceptable if shown to be equivalent to the listed revision, or if otherwise
formally accepted by the governing civil aviation authority; earlier revisions are not acceptable.
2.2 ASTM Standards:
This specification is under the jurisdiction of ASTM Committee F44 on General Aviation Aircraft and is the direct responsibility of Subcommittee F44.50 on Systems
and Equipment.
Current edition approved June 1, 2023Nov. 1, 2023. Published July 2023December 2023. Originally approved in 2017. Last previous edition approved in 20212023 as
F3233/F3233M–21. DOI: 10.1520/F3233_F3233M-23.–23. DOI: 10.1520/F3233_F3233M-23A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3233/F3233M − 23a
F3060 Terminology for Aircraft
F3061/F3061M Specification for Systems and Equipment in Aircraft
F3116/F3116M Specification for Design Loads and Conditions
F3117/F3117M Specification for Crew Interface in Aircraft
F3120/F3120M Specification for Ice Protection for General Aviation Aircraft
F3174/F3174M Specification for Establishing Operating Limitations and Information for Aeroplanes
F3229/F3229M Practice for Static Pressure System Tests in Small Aircraft
F3230 Practice for Safety Assessment of Systems and Equipment in Small Aircraft
2.3 CARs Standard:
CAR 523 Normal, utility, aerobatic and commuter category aeroplanes and Airworthiness manual chapter 523 – Normal, utility,
aerobatic and commuter category aeroplanes
2.4 EASA Standard:
CS-23 Certification Specifications for Normal-Category Aeroplanes
2.5 FAA Technical Standard Orders:
TSO-C10 Pressure Altimeter Systems
TSO-C209 Electronic Flight Instrument System (EFIS) Display
2.6 Federal Standard:
14 CFR 23 Code of Federal Regulations Title 14 Part 23—Airworthiness Standards: Normal Category Airplanes
3. Terminology
3.1 Terminology specific to this specification is provided below. For general terminology, refer to Terminology F3060.
3.2 Definitions:
3.2.1 aircraft type code, n—an Aircraft Type Code (ATC) is defined by considering both the technical considerations regarding
the design of the aircraft and the airworthiness level established based upon risk-based criteria; the method of defining an ATC
applicable to this specification is defined in SpecificationPractice F3061/F3061MF3230.
3.2.2 continued safe flight and landing, n—continued safe flight and landing as applicable to this specification is defined in
Specification F3061/F3061M.
3.2.3 high speed, n—an aircraft’s performance level is considered high speed if V or V is greater than 463 km/h [250
NEMO NO
knots], or M is greater than M0.6.
MO
3.2.4 instrument, n—the term instrument includes devices that are physically contained in one unit or component, and devices that
are composed of two or more physically separate units or components connected together (such as a remote indicating gyroscopic
direction indicator that includes a magnetic sensing element, a gyroscopic unit, an amplifier, and an indicator connected together).
3.2.5 low speed, n—an aircraft’s performance level is considered low speed if V or V is less than or equal to 463463 km
NEMO NO
km/h ⁄h [250 knots], or M is less than or equal to M0.6.
MO
3.2.6 primary display, n—primary display refers to the display of a parameter that is located such that the pilot looks at it first when
wanting to view that parameter.
3.2.7 sensitive altimeter, n—an instrument that measures altitude as a function of atmospheric pressure typically with an adjustable
barometric scale that allows the reference pressure to be set to a range of predefined atmospheric pressure references. The
“sensitive” element of the altimeter relates to the sensitivity of the instrument’s displayed change in altitude over the total range
of display. (For some examples of sensitive altimeter implementations, see TSO-C10( ) or TSO-C209( )).
4. Instrumentation
NOTE 1—Table 1 provides correlation between various Aircraft Type Codes and the individual requirements contained within this section; refer to 3.2.1.
For each subsection, an indicator can be found under each ATC character field; three indicators are used:
Available from Transport Canada, 330 Sparks St., Ottawa, ON K1A 0N5, https://tc.canada.ca/en.
Available from European Union Aviation Safety Agency (EASA), Konrad-Adenauer-Ufer 3, D-50668 Cologne, Germany, https://www.easa.europa.eu.
Available from U.S. Government Publishing Office (GPO), 732 N. Capitol St., NW, Washington, DC 20401, http://www.gpo.gov.
F3233/F3233M − 23a
TABLE 1 ATC Compliance Matrix, Section 4
Certification Level Number of Type of Stall Speed Cruise Speed Meteorological Altitude Maneuvers
Engines Engine(s) Conditions
Section
1 2 3 4 S M R T L M H L H D N I L H N A
4.1
4.1.1
4.1.2
4.1.3
4.1.4 C C
4.1.5 ×
4.1.6
4.1.7
4.1.8
4.1.9
4.1.10
4.1.11 × × ×
4.1.12 × × ×
4.1.13 × × × × ×
4.1.13.1 × × × × ×
4.1.13.2 × × × × ×
4.1.13.3 × × × × ×
4.1.13.4 × × × × ×
4.1.13.5 × × × × ×
4.1.13.6 × × × × ×
4.1.14
4.1.15
4.2
4.2.1
4.2.2
4.2.3
4.2.4 × ×
4.2.5 × ×
4.2.6
4.2.7 C C C
4.3
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.3.6 × × ×
4.3.5 × × ×
4.3.6.1 × × ×
4.3.5.1 × × ×
4.3.6.2 × × ×
4.3.5.2 × × ×
4.3.7 ×
4.3.6 ×
4.3.8 × × ×
4.3.7 × × ×
4.4
4.4.1
4.4.2
4.4.3
4.4.4
4.4.5 C C C
4.4.6
4.4.7
4.4.8
4.4.8.1
4.4.8.2
4.4.9
4.4.10 C C C
4.5
4.5.1
4.5.1.1
4.5.1.2
4.5.1.3 × × × × × ×
4.5.1.4 C C C
4.5.1.5 C C C
4.6
4.6.1
4.6.1.1
4.6.1.2
4.6.1.3
4.6.2 C C C
F3233/F3233M − 23a
TABLE 1 Continued
Certification Level Number of Type of Stall Speed Cruise Speed Meteorological Altitude Maneuvers
Engines Engine(s) Conditions
Section
1 2 3 4 S M R T L M H L H D N I L H N A
4.6.3 C C C
4.6.4 × ×
4.6.4.1 × ×
4.6.4.2 × ×
An empty cell ( ) in all applicable ATC character field columns indicates that an aircraft shall meet the requirements of that subsection.
A white circle (○) in multiple columns indicates that the requirements of that subsection are not applicable to an aircraft only if all such ATC character
fields are applicable.
A mark-out (×) in any of the applicable ATC character field columns indicates that the requirements of that subsection are not applicable to an aircraft
if that ATC character field is applicable.
Example—An aircraft with an ATC of 1SRLLDLN is being considered. Since all applicable columns are empty for 4.1.3, that subsection is applicable
to the aircraft. Since both the “R” engine type column and the “L” cruise speed column for 4.1.4 contain white circles, then that subsection is not
applicable; however, for an aircraft with an ATC of 1SRLHDLN, 4.1.4 would be applicable since the “H” cruise speed column does not contain a white
circle. 4.1.5 would not be applicable to either aircraft, since it contains an × in the “R” engine type column.
4.1 Flight and Navigation Instruments:
4.1.1 A means to determine airspeed shall be provided.
4.1.2 A means to determine altitude shall be provided.
4.1.3 A means to determine aircraft heading or direction of flight shall be provided.
NOTE 2—The choice of technology to meet this requirement may be mandated by some governing aviation authorities due to external requirements; for
example, a magnetic direction indicator.
4.1.4 A means to determine free air temperature shall be provided.
4.1.5 A speed warning device shall be provided for turbine-engine-powered aircraft.
4.1.6 A speed warning device shall be provided for aircraft for which V /M and V /M are established under Specification
MO MO D D
F3116/F3116M “Design Airspeeds” and Specification F3174/F3174M “Establishing Operating Limitations” if V /M is
MO MO
greater than 0.8 V /M .
D D
4.1.7 Any speed warning device required by 4.1.5 or 4.1.6 shall give effective aural warning (differing distinctively from aural
warnings used for other purposes) to the pilots whenever the speed exceeds V plus 11.11 km/h [6 knots] or M + 0.01.
MO MO
4.1.8 The upper limit of the production tolerance for any speed warning device required by 4.1.5 or 4.1.6 shall not exceed the
prescribed warning speed.
4.1.9 The lower limit of any speed warning device required by 4.1.5 or 4.1.6 shall be set to minimize nuisance warnings.
4.1.10 If an attitude display is installed, the instrument design shall not provide any means, accessible to the flight crew, of
adjusting the relative positions of the attitude reference symbol and the horizon line beyond that necessary for parallax correction.
4.1.11 If airspeed limitations vary with altitude, the airspeed indicator shall have a maximum allowable airspeed indicator showing
the variation of V with altitude.
MO
4.1.12 The altimeter shall be a sensitive type.
4.1.13 A third attitude instrument shall be provided that meets the requirements of 4.1.13.1 – 4.1.13.6.
4.1.13.1 The third attitude instrument shall be powered from a source independent of the electrical generating system.
4.1.13.2 The third attitude instrument shall continue reliable operation for a minimum of 30 min after total failure of the electrical
generating system.
F3233/F3233M − 23a
4.1.13.3 The third attitude instrument shall operate independently of any other attitude indicating system.
4.1.13.4 The third attitude instrument shall be operative without selection after total failure of the electrical generating system.
4.1.13.5 The third attitude instrument shall be located in a position acceptable to the governing civil aviation authority that will
make it plainly visible to and usable by any pilot at the pilot’s station.
4.1.13.6 The third attitude instrument shall be appropriately lighted during all phases of operation.
4.1.14 Instrument panel vibration may not damage, or impair the accuracy of, any instrument.
4.1.15 The instrument lights shall have enough distance or insulating material between current-carrying parts and the housing so
that vibration in flight will not cause shorting.
4.2 Electronic Display Instrument Systems:
4.2.1 Electronic display indicators shall meet the arrangement and visibility requirements of Specification F3117/F3117M.
4.2.2 Electronic display indicators shall not inhibit the primary display of attitude, airspeed, altitude, or powerplant parameters
needed by any pilot to set power within established limitations, in any normal mode of operation.
4.2.3 Electronic display indicators shall not inhibit the primary display of powerplant parameters needed by any pilot to properly
set or monitor powerplant limitations during the engine starting mode of operation.
4.2.4 Electronic display indicators shall have an independent magnetic direction indicator and either an independent secondary
mechanical altimeter, airspeed indicator, and attitude instrument or electronic display of parameters for altitude, airspeed, and
attitude that are independent from the aircraft’s primary electrical power system.
4.2.5 If secondary instruments are installed to comply with 4.2.4, they may be installed in panel positions that are displaced from
the primary positions specified by Specification F3117/F3117M, but shall be located where they meet the pilot’s visibility
requirements of Specification F3117/F3117M.
4.2.6 Electronic display indicators shall provide, where appropriate, direction and rate of change of the parameter being displayed
to the pilot.
4.2.7 The electronic display indicators, including their systems and installations, and considering other aircraft systems, shall be
designed so that one display of information essential for continued safe flight and landing will be available within 1 s 1 s to the
crew by a single pilot action or by automatic means for continued safe operation, after any single failure or probable combination
of failures (refer to Practice F3230).
4.3 Airspeed Indicating System:
4.3.1 Each airspeed indicating instrument shall be calibrated to indicate true airspeed (at sea level with a standard atmosphere)
with a minimum practicable instrument calibration error when the corresponding pitot and static pressures are applied.
4.3.2 Each airspeed system shall be calibrated in flight to determine the system error.
4.3.2 Each airspeed system shall be calibrated in flight to determine the system error. The system error, including position error,
but excluding the airspeed indicator instrument calibration error, shall not exceed 3 % of the calibrated airspeed or 9.3 km/h [5
knots], whichever is greater, throughout the following speed ranges: 1.3 V to V /M or V , whichever is appropriate with
S1 MO MO NE
flaps retracted; and, 1.3 V to V with flaps extended.
S1 FE
4.3.3 The design and installation of each airspeed indicating system shall provide positive drainage of moisture from the pitot
static plumbing.
4.3.4 If certification for instrument flight rules or flight in icing conditions is requested, each airspeed system shall have a heated
pitot tube or an equivalent means of preventing malfunction due to icing; refer to Specification F3120/F3120M.
F3233/F3233M − 23a
4.3.5 Each airspeed system shall be calibrated to determine the system error during the accelerate-takeoff ground run.
4.3.5.1 The airspeed system ground run calibration shall be determined from 0.8 of the minimum value of V to the maximum
value of V , considering the approved ranges of altitude and weight.
4.3.5.2 The airspeed system ground run calibration shall be determined assuming an engine failure at the minimum value of V .
4.3.6 Aircraft with high speed performance levels (refer to 3.2.3) shall meet the requirements of 4.3.64.3.5, 4.3.6.14.3.5.1, and
4.3.6.24.3.5.2 regardless of seating capacity.
4.3.7 Where duplicate airspeed indicators are required, their respective pitot tubes shall be far enough apart to avoid damage to
both tubes in a collision with a bird.
4.4 Static Pressure System:
4.4.1 Each instrument provided with static pressure case connections shall be so vented that the influence of aircraft speed, the
opening and closing of windows, airflow variations, moisture, or other foreign matter will least affect the accuracy of the
instruments except as noted in Specification F3120/F3120M.
4.4.2 The design and installation of a static pressure system shall be such that positive drainage of moisture is provided.
4.4.3 The design and installation of a static pressure system shall be such that chafing of the tubing, and excessive distortion or
restriction at bends in the tubing, is avoided.
4.4.4 The design and installation of a static pressure system shall be such that the materials used are durable, suitable for the
purpose intended, and protected against corrosion.
4.4.5 To demonstrate the integrity of the static pressure system, a proof test shall be conducted for unpressurized aircraft in
accordance with Practice F3229/F3229M.
4.4.6 To demonstrate the integrity of the static pressure system, a proof test shall be conducted for pressurized aircraft in
accordance with Practice F3229/F3229M.
4.4.7 If certification for instrument flight rules or flight in icing conditions is requested and a static pressure system is necessary
for the functioning of instruments, systems, or devices, the static pressure system shall comply with the provisions of Specification
F3120/F3120M.
4.4.8 Except as provided in 4.4.9, if the static pressure system incorporates both a primary and an alternate static pressure source,
the means for selecting one or the other source shall be designed in accordance with 4.4.8.1 and 4.4.8.2.
4.4.8.1 When either static pressure source is selected, the other source shall be blocked off.
4.4.8.2 Both static pressure sources shall not be blocked off simultaneously.
4.4.9 For unpressurized aircraft, 4.4.8.1 does not apply if it can be demonstrated that the static pressure system calibration, when
either static pressure source is selected, is not changed by the other static pressure source being open or blocked.
4.4.10 Each static pressure system shallmust be calibrated in accordance with Practiceflight to determine the system error. The
system error, in indicated pressure altitude, at sea-level, with a F3229/F3229M.standard atmosphere, excluding instrument
calibration error, may not exceed 69 m [630 ft] per 185 km ⁄h [100 knots] speed for the appropriate configuration in the speed
range between 1.3 V with flaps extended, and 1.8 V with flaps retracted. However, the error need not be less than 69 m
S0 S1
[630 ft].
4.5 Direction Indicator:
4.5.1 If a magnetic direction indicator is used to satisfy the requirements of 4.1.3, the following requirements shall be met.
F3233/F3233M − 23a
4.5.1.1 Except as provided in 4.5.1.3 or 4.5.1.4, each magnetic direction indicator shall be installed so that its accuracy is not
excessively affected by the aircraft’s vibration or magnetic fields.
4.5.1.2 Except as provided in 4.5.1.3 or 4.5.1.4, the compensated installation of the magnetic direction indicator shall not have
a deviation in level flight greater than 10° on any heading.
4.5.1.3 The compensated installation of the magnetic direction indicator may deviate more than 10° when a radio is transmitting,
but shall not exceed 15°.
4.5.1.4 A magnetic nonstabilized direction indicator may deviate more than 10° due to the operation of electrically powered
systems such as electrically heated windshields if either a magnetic stabilized direction indicator, which does not have a deviation
in level flight greater than 10° on any heading, or a gyroscopic direction indicator, is installed.
4.5.1.5 Deviations of a magnetic nonstabilized direction indicator of more than 10° shall be placarded in accordance with
Specification F3117/F3117M.
4.6 Instruments Using a Power Source:
4.6.1 Each instrument that uses a power source shall have a means to indicate to the crew if power is not adequate to sustain proper
instrument performance.
4.6.1.1 In showing compliance with 4.6.1, the power shall be sensed at the instrument, not at the power source only.
4.6.1.2 In showing compliance with 4.6.1, for electric and vacuum/pressure instruments, the power is considered to be adequate
when the voltage or the vacuum/pressure, respectively, is within approved limits.
4.6.1.3 If a separate indicator is used to meet the requirements of 4.6.1, it shall be located so that the pilot using the instruments
can monitor the indicator with minimum head and eye movement.
4.6.2 The installation and power supply systems for instruments that use a power source shall be designed so that the failure of
one instrument will not interfere with the proper supply of energy to the remaining instruments.
4.6.3 The installation and power supply systems for instruments that use a power source shall be designed so that the failure of
the energy supply from one source will not interfere with the proper supply of energy from any other source.
4.6.4 For certification for Instrument Flight Rules (IFR) operations, the heading, altitude, airspeed, and attitude instruments shall
meet the requirements of either 4.6.4.1 or 4.6.4.2.
4.6.4.1 In showing compliance with 4.6.4, there shall be two independent sources of power (not driven by the same engine on
multiengine aircraft), and a manual or an automatic means to select each power source.
4.6.4.2 As an alternative to the requirements of 4.6.4.1, there shall be a separate display of parameters for heading, altitude,
airspeed, and attitude that has a power source independent from the aircraft’s primary electrical power system.
5. Keywords
5.1 electronic display; indication; instrumentation; instruments
F3233/F3233M − 23a
ANNEX
(Mandatory Information)
A1. CORRELATION OF STANDARD CONTENT AND THE RULES
A1.1 See Table A1.1.
A1.2 Means of Compliance Correlation Sorted by FAA 14 CFR Rule
A1.2.1 See Table A1.2.
NOTE A1.1—The specification sections shown in the specification column will be at the highest level at which everything below that level is the same
as the level shown.
A1.3 Means of Compliance Correlation Sorted by EASA CS-23 Rule
A1.3.1 See Table A1.3.
NOTE A1.2—The specification sections shown in the specification column will be at the highest level at which everything below that level is the same
as the level shown.
F3233/F3233M − 23a
TABLE A1.1 Means of Compliance Correlation Sorted by Standard Section
Specification Rev Section Subpart Rule amndt64 Subpart CS23 amndt5
F3233/F3233M 23 4.1.1 F 23.2500a F 23.2500b
F3233/F3233M 23 4.1.2 F 23.2500a F 23.2500b
F3233/F3233M 23 4.1.3 F 23.2500a F 23.2500b
F3233/F3233M 23 4.1.4 F 23.2500a F 23.2500b
F3233/F3233M 23 4.1.5 F 23.2500a F 23.2500b
F3233/F3233M 23 4.1.5 G 23.2605b G 23.2605b
F3233/F3233M 23 4.1.6 F 23.2500a F 23.2500b
...