Ever wondered what goes on in the cockpit during a flight? At the Mach Loop valleys, chances are you will be able to see right into the cockpit as planes fly past.

The Mach Loop, a series of valleys near Dolgellau in north Wales, is used regularly by the British Royal Air Force and the United States Air Force for low-flying training, which means that the planes are allowed to fly as low as 76m above ground.

This area is popular with plane spotters, who trek up the hillside to photograph the fighter jets flying near or even below them.

According to the Daily Mail, the aircraft fly so close to the sides of the valley that photographers can clearly see into their cockpits, such as in the case of this US Air Force F-15 fighter jet (above), which was blazing through the countryside on on Tuesday.

Low flying is an important skill for military pilots in order to avoid enemy radar if they are ever faced with flying in a combat zone, reported the Daily Mail.

By flying low, the pilots are able to mask the presence of their aircraft using the terrain.