The Civil Aviation Authority (CAA) has announced that Dorset and Somerset Air Ambulance (DSAA) will benefit from a share of more than £200,000 of funding to allow air ambulances to land more safely in poor weather conditions.

Henstridge Airfield, the base of DSAA was one of five helicopter landing sites selected to benefit from the Global Navigation Satellite System (GNSS) Programme, run by the UK CAA and Department for Transport.

DSAA’s flight operations are bound by CAA regulations that stipulate the minimum allowable cloud base to allow us to continue flying visually with reference to ground features. If the cloud base is below the minima, then we can fly in cloud using our flight instruments, but only if there is a means to safely leave the cloud at our destination; without that means we are unable to fly with the cloud base below visual minima.

helicopter flying above the clouds at sunset

For DSAA, this applies to visibility and cloud levels at Henstridge Airfield primarily, and then at destination locations. This means that if the cloud level is below minimum visual levels at Henstridge, our Critical Care Team are unable to travel by air to reach patients in need. Furthermore, if they are on a mission and the weather deteriorates back at base, the aircraft could become stranded in a field or at hospital, resulting in a loss of operating hours (due to it needing to be recovered) and patients that require life-saving critical care may not be reached.

One example of this took place last month when our aircraft could not return to base after a job one evening due to low cloud at Henstridge. Instead it had to spend the night at a different heliport at the edge of our region and was not able to return until the weather had cleared during the middle of the next day.

Traditionally, aircraft flying to an airfield have used ground-based systems to enable them to make an approach to their destination. The aircraft can pick up signals from the ground-based system that then interact with onboard systems to give the pilot directional and height cues, enabling them to make a safe approach to the runway; autopilot systems on modern aircraft are also able to use this information to fly these approaches without pilot intervention.

With the advent of GNSS satellites and the 3D information they can provide, airfield approaches can now be made without having to rely on the ground-based systems, if the aircraft is fitted with the appropriate equipment. In the case of above, A GNSS approach would have enabled the aircraft to return to base, be restocked and re-equipped ready for another job that evening, and subsequently available for the day crew to respond to further taskings the next day.

As DSAA’s AW169 helicopter is equipped to carry out GNSS approaches and our pilots are licenced to fly them, the charity submitted a bid to the CAA at the end of September 2022.

We are delighted with the news that Henstridge Airfield is now part of the GNSS programme as it fully supports the charity’s commitment to reaching more patients who need critical care.

More information from the CAA on this topic can be found by visiting: