Originally Posted by
chevvron
Police helicopters have a police siren, I've heard them on several occasions; don't know about ambulance helicopters.
The police heli I flew some years ago was retro-fitted with "SkyShout". I didn't think it was worth carrying the extra weight of it (we were already very payload limited) but it was decided well above my payscale.
The first time we were tasked to use it was to warn people in the vicinity of a chemicals factory that there had been a dangerous acid gas leak drifting their way, so they must stay indoors and close windows and doors etc. Unfortunately it had the opposite effect, people came out to see what all the noise from the helicopter was about - so we bu££ered off quick and I don't think we ever used it again in my time on the unit.