319 

Federal Aviation Administration, DOT 

§ 23.1457 

§ 23.1453

Protection of oxygen equip-

ment from rupture. 

(a) Each element of the oxygen sys-

tem must have sufficient strength to 
withstand the maximum pressure and 
temperature, in combination with any 
externally applied loads arising from 
consideration of limit structural loads, 
that may be acting on that part of the 
system. 

(b) Oxygen pressure sources and the 

lines between the source and the shut-
off means must be: 

(1) Protected from unsafe tempera-

tures; and 

(2) Located where the probability and 

hazard of rupture in a crash landing 
are minimized. 

[Doc. No. 27806, 61 FR 5170, Feb. 9, 1996] 

§ 23.1457

Cockpit voice recorders. 

(a) Each cockpit voice recorder re-

quired by the operating rules of this 
chapter must be approved and must be 
installed so that it will record the fol-
lowing: 

(1) Voice communications trans-

mitted 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 loud-
speaker system, if there is such a sys-
tem and if the fourth channel is avail-
able in accordance with the require-
ments of paragraph (c)(4)(ii) of this sec-
tion. 

(6) If datalink communication equip-

ment is installed, all datalink commu-
nications, using an approved data mes-
sage set. Datalink messages must be 
recorded as the output signal from the 
communications unit that translates 
the signal into usable data. 

(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 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, 
so that the intelligibility of the re-
corded communications is as high as 
practicable 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 handheld microphone, 
headset, or speaker used at the first 
pilot station. 

(2) For the second channel from each 

boom, mask, or handheld 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 handheld 

microphone, headset, or speaker used 
at the station for the third and fourth 
crewmembers. 

(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) And that 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 

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