The SAS 'Blue Thunder' helicopter was spotted hovering high above the city of Birmingham, England.

The secretive helicopter, which does not show up on flight apps as its transponder is usually switched off or scrambled to help hide its location, was steady in the air, not moving for several minutes, obviously looking at something towards the ground on Wednesday 26 February evening at approximately 7pm GMT.

Birmingham in the West Midlands isn't a stranger to helicopter activities, with the police force's own chopper taking to the skies most days and nights, however the elite military unit's aircraft was over twice the normal height as the police's version.

The Blue Thunder is coloured white on the base and dark blue on the top and is flown by 658 Squadron Army Air Corps. The Squadron is co-located with the 22nd Special Air Service Regiment (22 SAS) at Stirling Lines, Herefordshire.

The Eurocopter AS365N3 Dauphin II is painted in civilian colours of blue and white. It is no Airwolf though, hovering high above the skyscrapers, it can be heard for miles around.

Whilst it is invisible to civilian air monitoring apps, you can certainly hear it and if you have good eyesight or a camera zoom lens, you can still see it too.