If you were watching BBC Breakfast this morning, you may have seen their reporter, Graham Satchell, heading out with our Flying Unit and finding out how we survey Britain from the skies.
We’ve actually been using aerial photography to carry out our surveys for almost 100 years. Originally, this had the advantage of capturing information from areas that surveyors found hard to visit on foot. Today, it means we can keep on top of the data capture process – making continuous revisions of the whole nation’s landscape.
Our in-house Flying Unit works with contractors to photograph around one-third of Britain every year – that’s 80,000 square kms of Britain’s urban, rural, moorland and mountain terrain. This imagery is a key component in many of our mapping databases and products and it’s the essence of OS MasterMap Imagery Layer.
So, as well as 270 surveyors working on the ground, we operate two aircraft which are used to take aerial photography and are based at East Midlands Airport. They capture on average 50,000 aerial images each flying season – roughly February to November. Our planes are two Cessna 404s called G-TASK and G-FIFA and they each fly with a highly-detailed digital camera – probably one the highest resolution cameras in the country – at 196 megapixels, which allows us to take high resolution images from the skies.
Getting aerial photography is obviously dependent on both the weather and clearance from Air Traffic Control and we rely on making the most of any bright, clear days to enable us to collect data. The team take advantage of the clear skies and work seven days a week. Five of our field surveyors work in the Flying Unit on a rotation basis as air camera operators, and they work with professional pilots.
Planning takes a considerable effort and the team will get together in January, along with some colleagues based at head office to prepare for the upcoming flying season. It isn’t simply a case of planning flight lines for each block of work, but also requires a diligent analysis of CAA Air Charts to understand how the proposed flying fits in within controlled air space. This also requires a good working relationship with NATS.
The team also have to set-up the aircraft for each flying season. On the ground in their office this means testing the data server, data transfer system, all associated IT systems and general office equipment. The aircraft set-up involves installing the digital camera system and all its components – one digital camera is stored at the end of the season and the other sent to Vexcel in Austria for calibration and maintenance. This is required considering these cameras are capturing 50,000+ images each year.
Once the aircraft is set-up, one of the initial tasks is to fly a pre-defined site to helps us calibrate the system – which enable the demanding accuracies we require for aerial triangulation. The work of the air camera operator requires an exceptional amount of focus and dedication and often means working odd hours and days to fit in with good weather windows over planned targets. Each year the good weather is unpredictable and the capture of photography ebbs and flows.
The team also fly over area when major events are taking place and often have a (fleeting) birds-eye view of sporting events and festivals over the summer. This year they happened to fly over the BoomTown Fair site near Winchester, shortly after a serious fire in the car park and captured the burnt out wreckage which we were able to share with Hampshire Fire and Rescue Service.
In between surveying targets, the team get an excellent opportunity to capture some amazing photos on their own phones and cameras which we regularly share on our Instagram account. Take a look at the selection below.
Liked reading about the Flying Unit? Find out how our surveying team capture their data on the ground too.
See more photos from the team in this BBC photo gallery.