Federal Aviation Administration, DOT § 23.1323

Home , Airspeed, Calibrated airspeed, Knot (unit)

(d) For each airplane, the flight in- the color differs sufficiently from the struments required by § 23.1303, and, as colors prescribed in paragraphs (a) applicable, by the operating rules of through (c) of this section to avoid pos- this chapter, must be grouped on the sible confusion. instrument panel and centered as near- (e) Effective under all probable cock- ly as practicable about the vertical pit lighting conditions. plane of each required pilot’s forward vision. In addition: [Amdt. 23–17, 41 FR 55465, Dec. 20, 1976, as (1) The instrument that most effec- amended by Amdt. 23–43, 58 FR 18976, Apr. 9, tively indicates the attitude must be 1993] on the panel in the top center position; § 23.1323 Airspeed indicating system. (2) The instrument that most effec- tively indicates airspeed must be adja- (a) Each airspeed indicating instru- cent to and directly to the left of the ment must be calibrated to indicate instrument in the top center position; true airspeed (at sea level with a stand- (3) The instrument that most effec- ard atmosphere) with a minimum prac- tively indicates altitude must be adja- ticable instrument calibration error cent to and directly to the right of the when the corresponding pitot and stat- instrument in the top center position; ic pressures are applied. (4) The instrument that most effec- (b) Each airspeed system must be tively indicates direction of flight, calibrated in flight to determine the other than the magnetic direction indi- system error. The system error, includ- cator required by § 23.1303(c), must be ing position error, but excluding the adjacent to and directly below the in- airspeed indicator instrument calibra- strument in the top center position; tion error, may not exceed three per- and cent of the calibrated airspeed or five (5) Electronic display indicators may knots, whichever is greater, through- be used for compliance with paragraphs out the following speed ranges: (d)(1) through (d)(4) of this section (1) 1.3 VS1 to VMO/MMO or VNE, which- when such displays comply with re- ever is appropriate with flaps re- quirements in § 23.1311. tracted. (e) If a visual indicator is provided to (2) 1.3 VS1 to VFE with flaps extended. indicate malfunction of an instrument, (c) The design and installation of it must be effective under all probable each airspeed indicating system must cockpit lighting conditions. provide positive drainage of moisture [Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as from the pitot static plumbing. amended by Amdt. 23–14, 38 FR 31824, Nov. 19, (d) If certification for instrument 1973; Amdt. 23–20, 42 FR 36968, July 18, 1977; flight rules or flight in icing conditions Amdt. 23–41, 55 FR 43310, Oct. 26, 1990; 55 FR is requested, each airspeed system 46888, Nov. 7, 1990; Amdt. 23–49, 61 FR 5168, Feb. 9, 1996] must have a heated pitot tube or an equivalent means of preventing mal- § 23.1322 Warning, caution, and advi- function due to icing. sory lights. (e) In addition, for commuter cat- If warning, caution, or advisory egory airplanes, the airspeed indi- lights are installed in the cockpit, they cating system must be calibrated to de- must, unless otherwise approved by the termine the system error during the Administrator, be— accelerate-takeoff ground run. The (a) Red, for warning lights (lights in- ground run calibration must be ob- dicating a hazard which may require tained between 0.8 of the minimum immediate corrective action); value of V1, and 1.2 times the maximum (b) Amber, for caution lights (lights value of V1 considering the approved indicating the possible need for future ranges of altitude and weight. The corrective action); ground run calibration must be deter- (c) Green, for safe operation lights; mined assuming an engine failure at and the minimum value of V1. (d) Any other color, including white, (f) For commuter category airplanes, for lights not described in paragraphs where duplicate airspeed indicators are (a) through (c) of this section, provided required, their respective pitot tubes

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must be far enough apart to avoid dam- the maximum cabin differential pres- age to both tubes in a collision with a sure or 100 feet, whichever is greater. bird. (3) If a static pressure system is pro- [Amdt. 23–20, 42 FR 36968, July 18, 1977, as vided for any instrument, device, or amended by Amdt. 23–34, 52 FR 1834, Jan. 15, system required by the operating rules 1987; 52 FR 34745, Sept. 14, 1987; Amdt. 23–42, of this chapter, each static pressure 56 FR 354, Jan. 3, 1991; Amdt. 23–49, 61 FR port must be designed or located in 5168, Feb. 9, 1996] such a manner that the correlation between air pressure in the static pres- § 23.1325 Static pressure system. sure system and true ambient atmos- (a) Each instrument provided with pheric static pressure is not altered static pressure case connections must when the airplane encounters icing be so vented that the influence of air- conditions. An antiicing means or an plane speed, the opening and closing of alternate source of static pressure may windows, airflow variations, moisture, be used in showing compliance with or other foreign matter will least af- this requirement. If the reading of the fect the accuracy of the instruments altimeter, when on the alternate static except as noted in paragraph (b)(3) of pressure system differs from the read- this section. (b) If a static pressure system is nec- ing of the altimeter when on the pri- essary for the functioning of instru- mary static system by more than 50 ments, systems, or devices, it must feet, a correction card must be pro- comply with the provisions of para- vided for the alternate static system. graphs (b) (1) through (3) of this sec- (c) Except as provided in paragraph tion. (d) of this section, if the static pressure (1) The design and installation of a system incorporates both a primary static pressure system must be such and an alternate static pressure source, that— the means for selecting one or the (i) Positive drainage of moisture is other source must be designed so provided; that— (ii) Chafing of the tubing, and exces- (1) When either source is selected, the sive distortion or restriction at bends other is blocked off; and in the tubing, is avoided; and (2) Both sources cannot be blocked (iii) The materials used are durable, off simultaneously. suitable for the purpose intended, and (d) For unpressurized airplanes, para- protected against corrosion. graph (c)(1) of this section does not (2) A proof test must be conducted to apply if it can be demonstrated that demonstrate the integrity of the static the static pressure system calibration, pressure system in the following man- when either static pressure source is ner: selected, is not changed by the other (i) Unpressurized airplanes. Evacuate static pressure source being open or the static pressure system to a pres- blocked. sure differential of approximately 1 (e) Each static pressure system must inch of mercury or to a reading on the altimeter, 1,000 feet above the aircraft be calibrated in flight to determine the elevation at the time of the test. With- system error. The system error, in in- out additional pumping for a period of dicated pressure altitude, at sea-level, 1 minute, the loss of indicated altitude with a standard atmosphere, excluding must not exceed 100 feet on the altim- instrument calibration error, may not ± eter. exceed 30 feet per 100 knot speed for (ii) Pressurized airplanes. Evacuate the appropriate configuration in the the static pressure system until a pres- speed range between 1.3 VS0 with flaps sure differential equivalent to the max- extended, and 1.8 VS1 with flaps re- imum cabin pressure differential for tracted. However, the error need not be which the airplane is type certificated less than 30 feet. is achieved. Without additional pump- (f) [Reserved] ing for a period of 1 minute, the loss of (g) For airplanes prohibited from indicated altitude must not exceed 2 flight in instrument meteorological or percent of the equivalent altitude of icing conditions, in accordance with

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