title-14-part-25-sec25-1323

343

Federal Aviation Administration, DOT

§ 25.1323

be plainly visible to the appropriate
crewmembers.

(d) Instrument panel vibration may

not damage or impair the accuracy of
any instrument.

(e) If a visual indicator is provided to

indicate malfunction of an instrument,
it must be effective under all probable
cockpit lighting conditions.

[Amdt. 25–23, 35 FR 5679, Apr. 8, 1970, as
amended by Amdt. 25–41, 42 FR 36970, July 18,
1977]

§ 25.1322

Flightcrew alerting.

(a) Flightcrew alerts must:
(1) Provide the flightcrew with the

information needed to:

(i) Identify non-normal operation or

airplane system conditions, and

(ii) Determine the appropriate ac-

tions, if any.

(2) Be readily and easily detectable

and intelligible by the flightcrew under
all foreseeable operating conditions,
including conditions where multiple
alerts are provided.

(3) Be removed when the alerting

condition no longer exists.

(b) Alerts must conform to the fol-

lowing prioritization hierarchy based
on the urgency of flightcrew awareness
and response.

(1) Warning: For conditions that re-

quire immediate flightcrew awareness
and immediate flightcrew response.

(2) Caution: For conditions that re-

quire immediate flightcrew awareness
and subsequent flightcrew response.

(3) Advisory: For conditions that re-

quire flightcrew awareness and may re-
quire subsequent flightcrew response.

egory, when necessary.

(2) Provide timely attention-getting

cues through at least two different
senses by a combination of aural, vis-
ual, or tactile indications.

(3) Permit each occurrence of the at-

tention-getting cues required by para-
graph (c)(2) of this section to be ac-
knowledged and suppressed, unless
they are required to be continuous.

(d) The alert function must be de-

signed to minimize the effects of false
and nuisance alerts. In particular, it
must be designed to:

(1) Prevent the presentation of an

alert that is inappropriate or unneces-
sary.

(2) Provide a means to suppress an

attention-getting component of an
alert caused by a failure of the alerting
function that interferes with the
flightcrew’s ability to safely operate
the airplane. This means must not be
readily available to the flightcrew so
that it could be operated inadvertently
or by habitual reflexive action. When
an alert is suppressed, there must be a
clear and unmistakable annunciation
to the flightcrew that the alert has
been suppressed.

(e) Visual alert indications must:
(1) Conform to the following color

convention:

(i) Red for warning alert indications.
(ii) Amber or yellow for caution alert

indications.

(iii) Any color except red or green for

advisory alert indications.

(2) Use visual coding techniques, to-

gether with other alerting function ele-
ments on the flight deck, to distin-
guish between warning, caution, and
advisory alert indications, if they are
presented on monochromatic displays
that are not capable of conforming to
the color convention in paragraph (e)(1)
of this section.

(f) Use of the colors red, amber, and

yellow on the flight deck for functions
other than flightcrew alerting must be
limited and must not adversely affect
flightcrew alerting.

[Amdt. 25–131, 75 FR 67209, Nov. 2, 2010]

§ 25.1323

Airspeed indicating system.

For each airspeed indicating system,

the following apply:

(a) Each airspeed indicating instru-

ment must be approved and must be
calibrated to indicate true airspeed (at
sea level with a standard atmosphere)
with a minimum practicable instru-
ment calibration error when the cor-
responding pitot and static pressures
are applied.

(b) Each system must be calibrated

to determine the system error (that is,
the relation between IAS and CAS) in
flight and during the accelerated take-
off ground run. The ground run calibra-
tion must be determined—

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14 CFR Ch. I (1–1–24 Edition)

§ 25.1324

(1) From 0.8 of the minimum value of

to the maximum value of V

, consid-

ering the approved ranges of altitude
and weight; and

(2) With the flaps and power settings

corresponding to the values determined
in the establishment of the takeoff
path under § 25.111 assuming that the
critical engine fails at the minimum
value of V

tion, excluding the airspeed indicator
instrument calibration error, may not
exceed three percent or five knots,
whichever is greater, throughout the
speed range, from—

(1)

to 1.23

SR1

, with flaps re-

tracted; and

(2) 1.23

SR0

with flaps in the

landing position.

(d) From 1.23 V

to the speed at

which stall warning begins, the IAS
must change perceptibly with CAS and
in the same sense, and at speeds below
stall warning speed the IAS must not
change in an incorrect sense.

(e) From V

to V

⁄

), the IAS must change perceptibly

with CAS and in the same sense, and at
higher speeds up to V

the IAS must

not change in an incorrect sense.

(f) There must be no indication of

airspeed that would cause undue dif-
ficulty to the pilot during the takeoff
between the initiation of rotation and

the achievement of a steady climbing
condition.

(g) The effects of airspeed indicating

system lag may not introduce signifi-
cant takeoff indicated airspeed bias, or
significant errors in takeoff or accel-
erate-stop distances.

(h) Each system must be arranged, so

far as practicable, to prevent malfunc-
tion or serious error due to the entry of
moisture, dirt, or other substances.

(i) Each system must have a heated

pitot tube or an equivalent means of
preventing malfunction in the heavy
rain conditions defined in Table 1 of
this section; mixed phase and ice crys-
tal conditions as defined in part 33, Ap-
pendix D, of this chapter; the icing con-
ditions defined in Appendix C of this
part; and the following icing conditions
specified in Appendix O of this part:

(1) For airplanes certificated in ac-

cordance with § 25.1420(a)(1), the icing
conditions that the airplane is certified
to safely exit following detection.

(2) For airplanes certificated in ac-

cordance with § 25.1420(a)(2), the icing
conditions that the airplane is certified
to safely operate in and the icing con-
ditions that the airplane is certified to
safely exit following detection.

(3) For airplanes certificated in ac-

cordance with § 25.1420(a)(3) and for air-
planes not subject to § 25.1420, all icing
conditions.

ABLE

1—H

EAVY

AIN

ONDITIONS FOR

IRSPEED

NDICATING

YSTEM

ESTS

Altitude range

Liquid water

content

Horizontal extent

Droplet MVD

(ft) (m)

(g/m3)

(km) (nmiles) (

0 to 10 000 .........................

0 to 3000 ............................

100

1000

6 5 3

2000

15 1 0

.5 2000

(j) Where duplicate airspeed indica-

tors are required, their respective pitot
tubes must be far enough apart to
avoid damage to both tubes in a colli-
sion with a bird.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–57, 49 FR 6849, Feb. 23,
1984; Amdt. 25–108, 67 FR 70828, Nov. 26, 2002;
Amdt. 25–109, 67 FR 76656, Dec. 12, 2002; Amdt.
25–140, 79 FR 65526, Nov. 4, 2014]