title-14-part-25-sec25-1321

342

14 CFR Ch. I (1–1–24 Edition)

§ 25.1317

manner after the airplane is exposed to
lightning.

[Doc. No. FAA–2010–0224, Amdt. 25–134, 76 FR
33135, June 8, 2011]

§ 25.1317

High-intensity Radiated

Fields (HIRF) Protection.

(a) Except as provided in paragraph

(d) of this section, each electrical and
electronic system that performs a func-
tion whose failure would prevent the
continued safe flight and landing of the
airplane must be designed and installed
so that—

(1) The function is not adversely af-

fected during and after the time the
airplane is exposed to HIRF environ-
ment I, as described in appendix L to
this part;

(2) The system automatically recov-

ers normal operation of that function,
in a timely manner, after the airplane
is exposed to HIRF environment I, as
described in appendix L to this part,
unless the system’s recovery conflicts
with other operational or functional
requirements of the system; and

(3) The system is not adversely af-

fected during and after the time the
airplane is exposed to HIRF environ-
ment II, as described in appendix L to
this part.

(b) Each electrical and electronic

system that performs a function whose
failure would significantly reduce the
capability of the airplane or the ability
of the flightcrew to respond to an ad-
verse operating condition must be de-
signed and installed so the system is
not adversely affected when the equip-
ment providing these functions is ex-
posed to equipment HIRF test level 1
or 2, as described in appendix L to this
part.

tem that performs a function whose
failure would reduce the capability of
the airplane or the ability of the
flightcrew to respond to an adverse op-
erating condition must be designed and
installed so the system is not adversely
affected when the equipment providing
the function is exposed to equipment
HIRF test level 3, as described in ap-
pendix L to this part.

(d) Before December 1, 2012, an elec-

trical or electronic system that per-
forms a function whose failure would
prevent the continued safe flight and

landing of an airplane may be designed
and installed without meeting the pro-
visions of paragraph (a) provided—

(1) The system has previously been

shown to comply with special condi-
tions for HIRF, prescribed under § 21.16,
issued before December 1, 2007;

(2) The HIRF immunity characteris-

tics of the system have not changed
since compliance with the special con-
ditions was demonstrated; and

(3) The data used to demonstrate

compliance with the special conditions
is provided.

[Doc. No. FAA–2006–23657, 72 FR 44025, Aug. 6,
2007]

NSTRUMENTS

: I

NSTALLATION

§ 25.1321

Arrangement and visibility.

(a) Each flight, navigation, and pow-

erplant instrument for use by any pilot
must be plainly visible to him from his
station with the minimum practicable
deviation from his normal position and
line of vision when he is looking for-
ward along the flight path.

(b) The flight instruments required

by § 25.1303 must be grouped on the in-
strument panel and centered as nearly
as practicable about the vertical plane
of the pilot’s forward vision. In addi-
tion—

(1) The instrument that most effec-

tively indicates attitude must be on
the panel in the top center position;

(2) The instrument that most effec-

tively indicates airspeed must be adja-
cent to and directly to the left of the
instrument in the top center position:

(3) The instrument that most effec-

tively indicates altitude must be adja-
cent to and directly to the right of the
instrument in the top center position;
and

(4) The instrument that most effec-

tively indicates direction of flight
must be adjacent to and directly below
the instrument in the top center posi-
tion.

must be closely grouped on the instru-
ment panel. In addition—

(1) The location of identical power-

plant instruments for the engines must
prevent confusion as to which engine
each instrument relates; and

(2) Powerplant instruments vital to

the safe operation of the airplane must

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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—