[2] The Pickett-Hamilton fort was designed to be lowered into the ground while it was not in use, to become inconspicuous and not interfere with the passage of taxiing aircraft or other vehicles.

The fort could be raised to about 2 feet 6 inches (0.76 m) above ground level where it would be a physical impediment to aircraft and vehicles and from where a small crew could fire with rifles or light machine guns.

The open spaces of airfields were very vulnerable to attack by airborne troops and it was felt that it was particularly important to defend them effectively.

The slightly smaller of the two cylinders slides into the larger and they are kept apart by small guard rollers on the moving part that engaged with grooves.

[citation needed] Initially, the lifting mechanism consisted of a standard 8-ton aeroplane jack that took three minutes to raise the fort.

[1][15] The pneumatic system operated with compressed air stored in cylinders: this allowed the fort to be raised and lowered quickly when speed was essential.

This design had two access hatches and, with a slightly larger underground chamber and the elimination of the central pneumatic ram the fort could have a crew of four men.

The forts were prone to flooding and they were not sufficiently strong to bear the weight of the heavy aircraft developed during the war.

[13][20] The management of Kent International Airport (formerly RAF Manston) donated a Pickett-Hamilton fort to Lashenden Air Warfare Museum.

Although the fort was originally intended to be buried on an airfield there was concern that putting it in the ground might, over time, degrade the concrete.

There is a reconditioned fort now displayed in the Linear Park at Kings Hill in Kent situated on the original West Malling Airfield.