Passengers are more likely to evacuate an aircraft where there is an obvious sign of danger however the absence of such danger may allow passengers to believe that they have more time than they think and as such that they may think of gathering and saving their belongings ahead of swiftly exiting an aircraft.
To prevent this occurring, or in the event of a panic situation, it is vitally important that Cabin Crew exert firm control over the situation and that commands and emergency instructions are given by the Cabin Crew.
All large passenger aircraft carry megaphones as part of their SEP emergency equipment and the ACR Electronics ACR-EM-1A "warble" emergency megaphone is standard SEP equipment many aircraft (it is approved for use onboard Boeing 737, 757,747,767 and 777 aircraft) and is a vital piece of aircraft emergency equipment and it's robust and rugged metal construction makes it ideal for day to day use for training Cabin Crew in aircraft emergency procedures.
All megaphones, including the ACR-EM-1A megpahone are shipped fully tested and fitted with brand new batteries before despatch, which means they can go straight into service.
Alternative megaphones to the ACR-EM-1A are the Federal Signal Corp A12 'Red' Megaphone and ACR-EM-2BA megaphone, which is physically the same as the 1A model but does not have a siren function.