I'm on iOS 16.7 and Watch OS 9.6.3 and mine do not match precisely. Currently showing an 11M difference.
I’ll bet you a cup of coffee that your latitude / longitude location is also off by several meters.
And, you know what? The time is probably off by at least dozens of milliseconds.
Use the Measure app on your iPhone — the one that uses your camera to stretch a virtual tape measure — and that’s probably off by a centimeter or so, certainly quite a few millimeters.
You’ve got a sound meter on your watch. Its display rounds to the nearest decibel. Guaranteed that it internally measures it in centibels or smaller. I wouldn’t be surprised if it’s off by a decibel or so; it’s certainly off by multiple centibels.
The Ultra has a water / diving depth gauge. I’m sure its accuracy is better than ten meters, but I wouldn’t be so sure if it’s accurate to the meter.
And yet, despite all those uncertainties in measurements, these devices are reasonably considered reliably highly precise and accurate. You have to go to expensive specialty equipment in most cases to do better. (Granted, not the iPhone’s virtual tape measure.)
At the end of the day, if you wanted to spend the money to develop a software suite plus a suitable mount for your watch to attach it to the dashboard of a small aircraft and then get FAA certification (no small / cheap task!), it’s plenty accurate and precise enough to serve as a full “glass cockpit,” with virtual horizon, turn/slip, GPS altimeter, the works. (Obviously, no air speed indicator, etc.) This is most remarkable in a rather inexpensive device you wear on your wrist.
And if you want something more accurate than is required for general aviation in your wristwatch … what on Earth are you doing that needs it?
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