Up in the air

I’m sure most of us have been more than happy with the lovely sunny, dry weather this spring, but how many can say that it’s helped them complete their work too? Personally, I’ve given more than one resentful glance out of the window at the glorious weather – not while writing for the blog of course! – but my colleague John has been embracing it whole heartedly. 

One of the planes our Flying Unit use

One of the planes our Flying Unit use

John is part of the Ordnance Survey Flying Unit. Working as part of our Remote Sensing department, the Flying Unit could be in the skies anytime that weather allows between early March and November.

Five people, some from our field teams and others from head office, work on a rota from our Blackpool airport base during the flying season. The two people on the rota spend around two weeks at a time in Blackpool, flying as often as the weather permits, including weekends.


Although the winter months are spent planning the areas that need to be flown the following spring and summer, the decision on where to fly on any specific day is made on the day itself. John ran me through a typical day:


“We usually get started around 6.30 am. We’ll have checked the weather the night before – usually the BBC – but we look at the weather in more detail on the morning to decide where we can fly. We’ve been based at Blackpool for some 50-odd years and can be in the Shetlands in two and a half hours or the Scilly Isles in an hour and a half. 

“It’s our decision on where to fly, but the pilot is in charge of the aircraft. We have two aircraft and use both at the same time. We work with around half a dozen pilots, also on a rota basis, and once we’re off the ground, they’re in control, leaving us free to manage the camera. When we can, we aim to fly for 6-8 hours, and we sometimes stay overnight at destinations if we would otherwise be flying back to the same area the next day.


“Before we started using GPS, it was a three man operation with a navigator taking the pilot along pre-determined lines drawn on a 1:50 000 map. Once on the required flight lines the camera operator would manually operate the camera. Now, we can do it with two people, pilot and camera operator, and it’s much more technical. Our cameras are programmed to shoot automatically along a preset route which is activated once the pilot’s on the right line.


“The cameras are fantastic. We have super-high resolution Vexcel Ultracam XP, at 196 megapixels – a bit more than your average point and shoot! There’s also a separate data storage unit, which can store almost 7 000 frames of photography. On a good day we might take 1 000-1 500 frames, so this makes it much easier to stay overnight now if we are flying a larger, remote area.


“Once we get back to our base we can download the information from the storage unit to a server. The file sizes are simply enormous, so rather than trying to send it down the wires to head office, we transfer the files to disk and courier them to Southampton.


“Obviously, that’s a good day if we manage an eight hour flying day and get all the data sent off to head office. With the British weather, on a good year, we are only able to fly one day in three. Anything above that is spectacular and we have been very, very lucky so far this year, meaning we are well ahead of schedule. We’ve taken full advantage of the sunny days and been out capturing as much photography as we can.


“We’ve been flying the Olympic sites regularly this year to keep that information up to date and that often means being around London. It’s very difficult to get airspace there and often, even with good weather, you have a long wait for clearance to fly at the right height.


“But I’ve been doing this job for around 20 years now and I’ve got to say it’s a lovely job, the best at Ordnance Survey.”


Next week we’ll be finding out more about Remote Sensing and what happens to the data once one of the Flying Unit sends it down to head office in Southampton.

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