Federal Aviation Agency ~\;:::. TiOts;
.,:,.,,,..-.
...~~
ADVISORY dlRC'ULAR ' .
.,~.I,~ -., \.*" :,_ r, . ...,_,J" .,: , : • . .._ ·~ I , _ SUBJECT : PORTABLE BATTERY-PCMERED MEGAPHONES NO: 121-6
AIR CARRIER AND COitMERCIAL OPERATIONS EFFECTIVE :
1/5/66
1. PURPOSE. This circular sets £orth an acceptable means £or complying with rules (applicable to various persons operating under Part 121 of the Federal Aviation Regulations) that prescribe the installation of approved megaphones.
2. REFERENCE REGUIATIONS. Sections 121.303(b) and 121.310(h).
3. ACCEPTABLE MFANS OF roMPLIANCE. A portable battery-powered megaphone is acceptable as "approved, 11 under§§ l21.303(b) and 121.310(h), for a particular aircraft i£
a. Hearing range and intelligibility tests are conducted on the aircraft to show that the amplified speech is heard and clearly understood throughout the interior cabin region .served by the megaphones, with the engines a££ and with all significant conditions associated with an accident (including the presence of passengers and the normally attendant confused din) appropriately simulated; and b 0 The megaphone reliably performs its intended £unction and is designed ( l} For ease 0£ handling, and use, with one hand, (2} With su££icient acoustical feedback suppression, and
(3) With a volume control.
~~~ eorge s. Moore Director Flight Standards Service