Field manual · 15/17

Apple Watch

The watch companion puts four things on your wrist: your grid, the bearing and distance to the target the phone is navigating to, a one-button mark, and start/stop for a track recording. It installs with the iPhone app — there is nothing separate to buy.

installing and pairing

The watch app ships inside the iPhone app. Install Tactical GPS on the iPhone and the watch app appears on the paired Apple Watch automatically, or install it by hand from the Watch app on the iPhone under Available Apps. It needs watchOS 10 or later.

Page between the four screens by swiping horizontally. Everything the watch shows follows the phone's settings — coordinate format, distance and altitude units, angle format, north reference and night vision all come across; there is nothing to configure on the wrist.

The watch position screen showing a grid reference, accuracy and altitude — Position

The watch navigation screen with a bearing arrow and distance — Nav

The watch track screen with live distance and elapsed time — Track

There is deliberately no map. The watch has no tile cache, and at that size an arrow with a distance under it is the better instrument than a postage stamp of terrain.

position

Your grid reference, large, in whatever format the phone is set to — MGRS, UTM, a national grid or lat/lon. Underneath it sits a row of readouts:

Format: Which format the grid above is written in
± horizontal: Accuracy of the current fix
± vertical: Altitude accuracy, when the fix reports one
Altitude: In your chosen altitude unit
Age: How old the fix is — 8s, 3m, 2h

Stale fixes are visible, not hidden

The age readout never shows zero and never goes blank. A fix that has stopped updating keeps counting up, so a watch that has quietly lost GPS looks different from one that is tracking. Before a first fix the grid reads —— ——.

Always On

On an Always-On display the screen keeps the grid legible at wrist-down instead of blanking it, so a glance still gives you a position.

A dot on the screen shows whether the phone is currently reachable. The watch keeps producing its own position either way.

The watch is WGS84-only. It carries no projection library, so the datum setting does not apply on the wrist, and a coordinate format set to a projected EPSG system falls back to UTM there. Every other format reads the same as on the phone.

nav

A bearing arrow pointing at the waypoint the phone has active, with the distance under it, the bearing in your north reference and an ETA when you are moving. When a route is running, the waypoint counter shows your place in it.

Arrival haptic

The watch taps your wrist when you reach the waypoint. It uses the phone's own arrival test, so the haptic fires at exactly the moment the phone considers the point reached — the two can never disagree. The haptic is armed once per waypoint and re-arms when the phone moves you to the next one.

The phone stays in charge

The watch never advances a route by itself. It mirrors the phone's current target and reports arrival; stepping, auto-advance and off-route logic all stay on the phone.

With nothing to navigate to the screen reads No target / Set one on the phone. Pick a pin or start a route on the iPhone and the arrow appears.

mark

One button. Press it and your current position becomes a pin in the active layer — the fastest way to record something without taking the phone out.

Marks queue when the phone is away

If the phone is out of range the mark is not lost. It goes into a stored outbox and is delivered when the two reconnect — carrying the time you pressed the button, not the time it was delivered, so the pin lands with the right timestamp.

Button reads	Meaning
MARK	Ready. Press to drop a pin at your position.
NO FIX	No usable GPS fix yet — there is no position to save.
PIN LIMIT	The free tier's pin cap is reached in the active layer.
UNLOCK ON IPHONE	The phone is locked, so the pin cannot be written yet.

If the active layer is a shared layer you only have read access to, the mark is refused on the phone rather than silently dropped. Make one of your own layers active first — see Layers & iCloud Sharing.

track

Start and stop a track recording from the wrist, with live distance and elapsed time. The recording is the phone's — the watch is a remote control and a readout, so the resulting session is the same one you would have got by pressing start on the phone.

Screen reads	Meaning
RECORD	Ready to start.
PAUSED	The session is paused, on either device.
PRO REQUIRED	Track recording is a Pro feature.
UNLOCK ON IPHONE	The phone is locked and cannot start the session.
SCREEN ON ONLY	The watch could not hold a background session — see below.

SCREEN ON ONLY is an honest warning, not an error. watchOS only keeps an app running with continuous location after wrist-down inside a workout session. When one cannot be started, the watch says so rather than implying a guarantee it cannot keep — it will keep counting while the screen is on and stop when the screen goes off.

No health data is read or written. The workout session exists purely to keep location alive; the distance shown is accumulated from GPS fixes, which is why it matches the track the phone saves.

Backtrack from the wrist hands the request to the phone, which sets the recorded track as the navigation target. The NAV screen then points you home.

what the watch will not do

No map and no tile cache. Basemaps, overlays, the grid and every drawing tool are phone-only.

No editing. You can create a pin with MARK, but naming, styling, attachments and deletion happen on the phone.

WGS84 only, and EPSG formats fall back to UTM.

Night vision is a palette, not a filter. The phone tints the whole screen through a display filter; watchOS has no clean equivalent, so the watch app redraws itself in red or green instead. The result reads the same at night.

The free-tier limits apply on the wrist too — the pin cap shows as PIN LIMIT and recording shows as PRO REQUIRED.

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