How a Man Down Device Works
Strip away the marketing and a man down device is a simple chain of sensors, logic and a network connection. Every link has to hold.
- Sensors monitor movement continuously: an accelerometer and gyroscope track motion and orientation in real time, tuned for industrial use.
- The device flags an abnormal event: a sharp deceleration consistent with a fall, or a change in orientation followed by no movement.
- A grace period allows for false alarms: most devices wait 10 to 30 seconds so the worker can cancel if they simply dropped the unit or sat down hard.
- The alert transmits with location: if not cancelled, the device sends GPS coordinates to a monitoring centre or nominated contacts.
- A human responds: a monitoring service or colleague tries to reach the worker, escalating to emergency services if there is no answer.
A device with excellent sensors but poor network coverage is no better than one with no man down feature at all, because the alert never leaves the device.
The Detection Methods, Explained
Most modern devices layer several of these together, because no single method catches every way a worker can end up in trouble.
Fall and Impact
An accelerometer measures the sudden G-force of a fall, distinguishing it from bending, sitting or climbing into a vehicle.
Tilt
If the device stays horizontal for a set time, it assumes the worker is down and starts a pre-alert.
No-Motion
Triggers if there is no movement at all for a set period, covering a collapse or medical event without a hard fall.
SOS and Check-Ins
A panic button for threats or being trapped while conscious, plus missed check-in alerts as an independent backstop.
Layering is what makes a lone worker system reliable. Fall detection alone will miss a slow collapse, which is exactly why no-motion detection and check-ins exist.
How the Alert Reaches Someone
The alert is only useful if it gets out, and plenty of NZ work sites sit outside reliable cellular coverage.
| Network | Best Suited For | Consideration |
|---|---|---|
| Cellular (4G/5G) | Urban and semi-rural sites with mobile coverage | Lower cost, but ineffective outside a coverage bubble |
| Satellite | Remote farms, forestry, backcountry, marine work | Works with no cellular signal, at higher device and plan cost |
| DMR radio | Crews already on a private radio network | Alerts go straight to nearby colleagues' radios for the fastest local response |
| Dual-mode | Teams moving between coverage and remote zones | Switches networks automatically during a shift |
GPS gives outdoor location. Indoors or under dense bush, Bluetooth beacons can supplement it so responders find the worker quickly.
Standalone Alarms vs Integrated Radios
Standalone pendants are simple wearable alarms, usually running over cellular. Two-way radios and PoC devices with man down built in combine communication and safety in one unit. If your team already carries radios every day, the integrated option is usually the simpler upgrade, and on a private DMR network it works with no mobile reception at all.
Monitored vs Self-Managed
A monitored service routes alarms to a 24/7 call centre for a recurring fee, which suits organisations without an on-site response team. A self-managed system sends alerts to your own supervisors, avoiding subscription costs and often getting a faster response from people who know the site.
Features Worth Checking
- Ruggedness: IP67 or higher to handle drops, dust and water.
- Battery life: comfortably a full shift, with a clear low-battery warning.
- Ease of use: a prominent SOS button and clear alarm indicators.
- False alarm control: adjustable sensitivity and a pre-alarm warning, so workers trust the system rather than switch it off.
Devices with Man Down Built In
Man down is increasingly built into the device your team already carries, rather than being a separate gadget.
Motorola TLK110
Lone worker and fall alert as standard, running over cellular through WAVE PTX for nationwide coverage.
View product →Mongoose VT904
Hardwired vehicle tracker that pairs with the optional SP904 security pack for SOS alerting, where the worker's location is part of the safety picture.
View product →Tait and Hytera's current commercial DMR ranges also build lone worker and man down capability into mid-tier and above handhelds. If your team already runs one of those brands, check whether your radios support it before buying a separate device.
Rolling It Out Properly
Set the Sensitivity for Your Actual Sites
Too sensitive and the device fires every time someone jumps off a truck deck, and workers start ignoring it. Not sensitive enough and a real fall goes unreported. Tune it during setup rather than trusting factory defaults, and test it in real conditions, on scaffolding or a quad bike, not an office corridor.
Write the Response Plan First
Before any device is switched on, document who receives the alert, what they need (name, GPS location, time) and the exact step-by-step response.
Train for Trust
Frame the device as a personal safety tool, not a tracking device. Show everyone how to cancel a pre-alarm, which cuts false activations and builds confidence in the system.
Man down works best as one layer of a wider setup. See our lone worker safety guide for the full picture, and our duress alarm guide for manual panic options.
Solutions for Key NZ Industries
| Industry | Recommended Solution | Key Features |
|---|---|---|
| Forestry, farming and agriculture | Satellite devices or a dedicated DMR system | IP67/68 hardware, accurate GPS for dense bush and large properties |
| Construction, transport and utilities | Two-way radios with man down built in | Clear audio in noise, long battery life, vehicle charging |
| Security, healthcare and social services | Discreet pendants or compact radios | Silent SOS, indoor and outdoor location |
Mobile Systems Limited has supplied and supported lone worker safety technology from Mount Maunganui for over 25 years. We look at your sites and coverage before recommending hardware, so the system fits how your team actually works.
