With our aviation collection rooted in vintage British styling – the C8 P2725 Automatic’s dial is inspired by the cockpit dashboard found inside the Hawker Hurricane – Paul Traynor revisits the idyllic era before GPS, when the primary means of navigating at 3000ft came from none other than the trusty watch…
It was at this point that I was reminded why the RAF provided us with full NATO-issue bone domes – or for those unfamiliar with pilot slang, a helmet – because Braithwaite had taken up his checklist and was beating me about the head with it.
Flight Lieutenant Braithwaite was my flying instructor. Diminutive (a result, he claimed, of having to eject from an uncooperative Canberra bomber) and worldly-wizened, he seemed somewhat upset at the fact that we were only 10 minutes into the flight and I was already – how shall I put this – uncertain of position. I really had no excuse – the sky was a pristine blue, and the visibility good enough to see all the way to Wales.
‘Where’s your watch you idiot?’
It seemed an inappropriate moment to explain that it was probably still at the bottom of a half-full pint of ale back in my student digs, the unfathomable outcome of some obscure drinking game the night before.
‘How do you expect to navigate without a watch?’
I had to admit he had a point.
Trying to match ground features to your map whilst in the air is an impossible task – everything looks the same. The trick is to use your watch to tell you where you should be and when to look out for confirmation. So, you plan your route via waypoints which will be distinctive from the air – a lake perhaps, or a power station – and you measure the distance. If it’s 12 nautical miles, and you plan to fly at 120 knots, then you know it should take you exactly 6 minutes to get there. You note the precise time of your departure, concentrate on flying an accurate heading and airspeed and, when 6 minutes have passed, you look out and check that the distinctive feature is directly below you.
Braithwaite was right. For this, you need a watch.
Of course, in the real world the wind is unlikely to be precisely as forecast, nor is it likely to blow at a steady pace. So in practice, when you look out you’ll either be short of your waypoint or beyond. This is annoying but also useful, since an estimate of the error will give you a better estimate of the actual wind. If you’re 2 miles short, you know that you’ve actually travelled 10 miles in 6 minutes so your groundspeed is 100 knots. If your airspeed was 120 knots, you can now deduce that the actual headwind component is 20 knots. If your next waypoint is, say, 20 miles beyond the first, you can now produce a revised ETA: 20 nautical miles at 100 knots is 12 minutes. So, note the time, get back to flying and in 12 minutes time look out of the window and start the whole process again.
Or maybe you need to make a specific arrival slot at your destination airport. Now you know your actual groundspeed you know by how much you need to increase your airspeed to cover a specific distance.
Sadly, the art of visual navigation with map, compass and watch has now largely been supplanted by GPS but the principles still survive in unexpected places. When a commercial jet is put into a holding pattern it’s done not by distance but by time: one minute outbound, one minute inbound, two thirty second turns and adjust for wind.
So, next time your flight into Heathrow gets diverted into the stack, just hope that your pilot remembered to bring his watch!
If you enjoy the vintage design cues of the C8 P2725 Automatic, our C8 Collection builds upon those aesthetic foundations with an array of horological complications, from the GMT functionality of the UTC Worldtimer, through to the Calibre SH21-powered Power Reserve Chronometer.