362 

14 CFR Ch. I (1–1–19 Edition) 

§ 25.1457 

position for recording voice commu-
nications originating at the first and 
second pilot stations and voice commu-
nications of other crewmembers on the 
flight deck when directed to those sta-
tions. The microphone must be so lo-
cated and, if necessary, the pre-
amplifiers and filters of the recorder 
must be so adjusted or supplemented, 
that the intelligibility of the recorded 
communications is as high as prac-
ticable when recorded under flight 
cockpit noise conditions and played 
back. Repeated aural or visual play-
back of the record may be used in eval-
uating intelligibility. 

(c) Each cockpit voice recorder must 

be installed so that the part of the 
communication or audio signals speci-
fied in paragraph (a) of this section ob-
tained from each of the following 
sources is recorded on a separate chan-
nel: 

(1) For the first channel, from each 

boom, mask, or hand-held microphone, 
headset, or speaker used at the first 
pilot station. 

(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 para-

graph (c)(4)(i) of this section are not re-
quired 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 posi-
tion of the interphone-transmitter key 
switch. The design shall ensure that 
sidetone for the flight crew is produced 
only when the interphone, public ad-
dress system, or radio transmitters are 
in use. 

(d) Each cockpit voice recorder must 

be installed so that— 

(1)(i) It receives its electrical power 

from the bus that provides the max-
imum reliability for operation of the 
cockpit voice recorder without jeopard-
izing service to essential or emergency 
loads. 

(ii) It remains powered for as long as 

possible without jeopardizing emer-
gency operation of the airplane. 

(2) There is an automatic means to 

simultaneously stop the recorder and 
prevent each erasure feature from func-
tioning, within 10 minutes after crash 
impact; 

(3) There is an aural or visual means 

for preflight checking of the recorder 
for proper operation; 

(4) Any single electrical failure exter-

nal to the recorder does not disable 
both the cockpit voice recorder and the 
flight data recorder; 

(5) It has an independent power 

source— 

(i) That provides 10 

±

1 minutes of 

electrical power to operate both the 
cockpit voice recorder and cockpit- 
mounted area microphone; 

(ii) That is located as close as prac-

ticable to the cockpit voice recorder; 
and 

(iii) To which the cockpit voice re-

corder and cockpit-mounted area 
microphone are switched automati-
cally in the event that all other power 
to the cockpit voice recorder is inter-
rupted either by normal shutdown or 
by any other loss of power to the elec-
trical power bus; and 

(6) It is in a separate container from 

the flight data recorder when both are 
required. If used to comply with only 
the cockpit voice recorder require-
ments, a combination unit may be in-
stalled. 

(e) The recorder container must be 

located and mounted to minimize the 
probability of rupture of the container 
as a result of crash impact and con-
sequent heat damage to the recorder 
from fire. 

(1) Except as provided in paragraph 

(e)(2) of this section, the recorder con-
tainer must be located as far aft as 
practicable, but need not be outside of 
the pressurized compartment, and may 
not be located where aft-mounted en-
gines may crush the container during 
impact. 

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