Sec. 25.1457 - Cockpit voice recorders.
(a) Each cockpit voice recorder required
by the operating rules of this chapter must be approved and must be
installed so that it will record the following:
(1) Voice communications transmitted
from or received in the airplane by radio.
(2) Voice communications of flight
crewmembers on the flight deck.
(3) Voice communications of flight
crewmembers on the flight deck, using the airplane's interphone system.
(4) Voice or audio signals identifying
navigation or approach aids introduced into a headset or speaker.
(5) Voice communications of flight
crewmembers using the passenger loudspeaker system, if there is such a
system and if the fourth channel is available in accordance with the
requirements of paragraph (c)(4)(ii) of this section.
(b) The recording requirements of
paragraph (a)(2) of this section must be met by installing a
cockpit-mounted area microphone, located in the best position for
recording voice communications originating at the first and second pilot
stations and voice communications of other crewmembers on the flight deck
when directed to those stations. The microphone must be so located and, if
necessary, the preamplifiers and filters of the recorder must be so
adjusted or supplemented, that the intelligibility of the recorded
communications is as high as practicable when recorded under flight
cockpit noise conditions and played back. Repeated aural or visual
playback of the record may be used in evaluating intelligibility.
(c) Each cockpit voice recorder must be
installed so that the part of the communication or audio signals specified
in paragraph (a) of this section obtained from each of the following
sources is recorded on a separate channel:
(1) For the first channel, from each
boom, mask, or hand-held microphone, headset, or speaker used at the first
(2) For the second channel from each
boom, mask, or hand-held microphone, headset, or speaker used at the
second pilot station.
(3) For the third channel -- from the
cockpit-mounted area microphone.
(4) For the fourth channel, from --
(i) Each boom, mask, or hand-held
microphone, headset, or speaker used at the station for the third and
fourth crew members; or
(ii) If the stations specified in
paragraph (c)(4)(i) of this section are not required or if the signal at
such a station is picked up by another channel, each microphone on the
flight deck that is used with the passenger loudspeaker system, if its
signals are not picked up by another channel.
(5) As far as is practicable all sounds
received by the microphone listed in paragraphs (c)(1), (2), and (4) of
this section must be recorded without interruption irrespective of the
position of the interphone-transmitter key switch. The design shall ensure
that sidetone for the flight crew is produced only when the interphone,
public address system, or radio transmitters are in use.
(d) Each cockpit voice recorder must be
installed so that --
(1) It receives its electric power from
the bus that provides the maximum reliability for operation of the cockpit
voice recorder without jeopardizing service to essential or emergency
(2) There is an automatic means to
simultaneously stop the recorder and prevent each erasure feature from
functioning, within 10 minutes after crash impact; and
(3) There is an aural or visual means
for preflight checking of the recorder for proper operation.
(e) The record container must be located
and mounted to minimize the probability of rupture of the container as a
result of crash impact and consequent heat damage to the record from fire.
In meeting this requirement, the record container must be as far aft as
practicable, but may not be where aft mounted engines may crush the
container during impact. However, it need not be outside of the
(f) If the cockpit voice recorder has a
bulk erasure device, the installation must be designed to minimize the
probability of inadvertent operation and actuation of the device during
(g) Each recorder container must --
(1) Be either bright orange or bright
(2) Have reflective tape affixed to its
external surface to facilitate its location under water; and
(3) Have an underwater locating device,
when required by the operating rules of this chapter, on or adjacent to
the container which is secured in such manner that they are not likely to
be separated during crash impact.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-2, 30 FR 3932, Mar. 26, 1965; Amdt. 25-16, 32 FR
13914, Oct. 6, 1967; Amdt. 25-41, 42 FR 36971, July 18, 1977; Amdt. 25-65,
53 FR 26143, July 11, 1988]