National Police Air Service: CAP 746 Compliance on a National Scale

With 30 years’ experience in the emergency response sectors, Skyview was thrilled to team up with the National Police Air Service (NPAS) to enhance their national weather monitoring network and improve accessibility to weather data.

Our weather monitoring equipment and software helps to ensure that when a helicopter leaves base, the pilots and controllers are able to remotely monitor real time weather changes and plan for diversions and changes when necessary.

About NPAS

The National Police Air Service (NPAS) provides continuous borderless air support to the 43 police forces of England and Wales from their national network of 14 bases. Whether carrying out tasks such as missing people searches, critical incidents, operational follows and vehicle pursuits, NPAS pilots and crews require data that is accurate and up-to-the-minute.

The Challenge

Police air support units face a multitude of challenges in their quest to protect our communities. Emergency response teams must comply with rigorous health and safety CAA legislation to ensure the safety of their crew once airborne, and the safety of the local residents on the ground. Whether they are following a high speed vehicle chase, conducting a missing person search, searching for stolen vehicles or assisting in a serious road traffic accident, they need to be certain of flight conditions to ensure a safe return to base. 

Cloud height and visibility are crucial factors for emergency response teams, and must be consistently and reliably monitored to ensure safety of all on board.

The winter months can be particularly hazardous when the temperature and dew point are close together. Fog and cloud can form in a very short timeframe and can make a safe return to base difficult. Any unplanned rerouting can cause problems especially with a limited fuel supply.

NPAS required a system to comply with strict legal requirements, particularly CAP 746, which specifically states that “accurate, timely and complete aerodrome meteorological observations are necessary to support safeand efficientair navigation”.

Skyview’s extensive experience of working with air ambulances, individual police air helicopters and offshore helicopters alike, ensures that we are well versed with sector specific legislation.

Our Solution

Each NPAS system installed by Skyview’s experienced team of engineers has been designed in accordance with specific CAP 746 requirements, ensuring that the meteorological equipment, sensors, processors and displays provide accurate and timely weather data to flight crews and ancillary staff.

Each NPAS site has in place accurate visibility sensors  and ceilometers using sophisticated laser technology to measure cloud height. Data from each sensor is fed back to Skyviews’ exclusive Skymet-i software, allowing current and historic data to be immediately accessible at any given time.  


In addition to the hardware provided, we were delighted to welcome NPAS on board as subscribers to our innovative weather monitoring web platform. Data from each base’s weather system is uploaded to, where it can be viewed from any location with an internet enabled PC, smartphone or tablet.

The NPAS teams selected the most relevant modules to their operations, including:

  • Current weather data
  • Partner weather information
  • Partner comparison
  • Partner webcam
  • Local weather
  • ATC
  • Forecast
  • Lightning
  • Historical Weather
  • Satellites & Charts
  • Aviation
  • Energy
  • Alerts provides access to an increasing number of weather stations around the UK, many of which are operated by other blue-light organisations or private aviation operations. This enhanced coverage of reporting stations along with TAFs, METARs and charts help staff and crew to predict, detect and assess approaching weather conditions and task accordingly.

“Fly” and “no-fly” limits for day and night operations can be pre-programmed into the system, enabling instant alerts by text and/or email should conditions deteriorate. Subsequent messages are then sent when conditions improve.

Skylink-pro’s ground breaking “partner site” module gives each team the option to view their nominated partner site’s weather data for further analysis and critical decision-making - an invaluable tool for such a large scale operation.

Service, maintenance and calibration for enhanced accuracy 

Skyview provides NPAS a service and maintenance contract to ensure that all sensors are working correctly and within set parameters. Routine maintenance is carried out to ensure sensors and ancillary equipment continues to operate within calibrated limits.