Essential Rescue Gear: Whistles

Scott Heiman — 4 August 2016

What’s the one thing 4WDers always have in their pockets? A set of car keys.

But, if you have been separated from your rig for whatever reason, your keys will not be that much use to you unless you’re MacGyver. At a time like this, you’ll be looking at what else you’re carrying in your pockets to help bring a rescue party to your aid.

Some people attach a small button LED torch to their key fob as an emergency signal for help at night or simply to guide their way around camp. But a torch won’t be much use in the daytime.

Have you ever seen SES volunteers on the news participating in a search for lost bushwalkers, hunters and 4WDers? They’re often blowing whistles, as are army personnel when they want to get someone’s attention in loud environments like on a gunnery range.

So we thought we’d share thoughts on why we need this under-rated device in the great outdoors.

The reality is that whistles are simply much louder than the human voice and their sound carries much further than shouting. In fact, as a general rule of thumb, a whistle sound will carry up to three times further than a really loud human yell for help. And consider this: if you’re in an emergency situation – particularly if you’re panicking a little – your voice may get rusty and go hoarse. Whistles take far less energy than yelling and can penetrate background noise, making you audible to rescuers.

If you find yourself needing to use a whistle, remember that there are internationally recognised distress signals for whistle blasts that will assist you to be found more quickly by camp mates or a professional search and rescue team. So it’s a good idea you and your party to know these before you step off.

International whistle signalling code:

• 1 whistle blast = ‘Where are you?

• 2 whistle blasts = ‘Come to me’

• 3 whistle blasts = ‘HELP’

Each whistle blast should last three seconds with one second in between blasts. Wait 30 seconds or longer to hear a reply, and repeat the signal. If you hear a reply, respond with one solid blast to help your searcher hone in on your position.

So think about it. Wouldn’t it be a good idea to put a whistle on your key chain just in case?  Better still, get one for each member of your family and travel party. In a country as big as ours, it doesn’t take much to get off the beaten track and become dislocated. Handheld CBs are great – but they need batteries. With whistles on hand, we can spend less time trying to keep everyone within range and safe – and more time doing the things we really enjoy when we head out into the scrub.


We tested the AMK SOL Fox 40 Sharx Emergency Whistle against four other whistles used by the Scouts, law enforcement officers, the military and search and rescue teams – people who really need a whistle to stand up to the rigours of the scrub.

We chose the Fox 40 Sharx as it is the preferred whistle of Les Stroud of Survivorman fame and survival instructor for the Canadian Military Forces. It is an approved and recommended sound-signalling device for coastguard volunteers worldwide and was developed from referee whistles that can be heard over crowds of thousands at the Olympics and FIFA World Cup.

Being made from polycarbonate and co-moulded elastomer makes it easy to handle, adaptive to outdoor conditions and slip-resistant. The properties of the elastomer material are manufactured to vary with temperature so the Fox 40 can be used between -20 and 80°C. While we didn’t subject the whistle to these extremes, the whistle is pea-less (no moving parts) which means it’s unlikely to freeze, jam or deteriorate. 

The manufacturer claims the whistle blast makes a screaming noise with a dual frequency tone of 120dB. At that rate, the AMK SOL Fox 40 Sharx Emergency Whistle should be louder than almost any ambient noise you might encounter – whether it’s breaking waves, gale-force winds, a waterfall or the sound of your 4WD’s engine. And we can attest that a simple and sharp one-second blow from a five-year-old was enough to get our ears ringing in a way that took us back to our first AC/DC concert.


AMK SOL claims the Fox 40 Sharx can be heard at up to 1.6km, but manufacturers generally test in a controlled environment using frequency, loudness, atmospheric pressure and humidity which, by applying formulaic fairy-dust, equal distance. That’s all well and good, but we were more interested in finding out what happens when you go out in the scrub. So that’s what we did.

We tested the Fox 40 Sharx against four other whistles at 1km, 800m and 500m in:

• the open, in ‘line of sight’ with still air

• the open, in ‘line of sight’ with slight cross wind

• lightly forested conditions, along a dirt road, in ‘line of sight’ with wind assist (i.e., with the listening party downwind)

What we found was that the distance calculated under the manufactured conditions was not the same as what we encountered in the bush. The best results we got from

the Fox 40 were at 800m, in the open in still air and in lightly forested conditions with a tail wind. That’s half the manufacturer’s claims. Even in the open, a slight cross wind swallowed the noise and the whistle could only be heard at the 500m mark during our test.

Even so, 800m is a good effort. The only louder whistle we could find in our test lineup was an old-school artillery pea-whistle that’s intended to be heard over the sound of military ordnance. These traditional whistles are great, but they’ve got their limitations when compared to the Fox 40. Whistles with peas can be ‘over-blown’ – at which point the whistle simply stops making a noise. Without a pea, the Fox 40 doesn’t have this problem. It also gets louder the harder you blow it. And this is unusual in a whistle.

The Fox 40 is made up of twin double chambers that are designed to self-clear if submerged in water. And we reckon this could be a very handy feature in many emergency scenarios. Add the hi-vis orange colouring, and the AMK SOL Fox 40 Sharx Emergency Whistle has got the credentials to make it a top choice for search and rescue, outdoor and personal safety. 

So, slip one on to your key fob and give yourself a little extra peace of mind when you head outdoors.


WE SAY: Hi-vis and bloody loud

RRP: $25

FROM: Various sport outlets, Australia-wide

Check out the full feature in issue #103 August 2016 of Camper Trailer Australia magazine. Subscribe today for all the latest camper trailer news, reviews and travel inspiration.


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