The Golden Ball monument is a prominent landmark that can be seen part-way between Princes Risborough and Wycombe Air Park, and roughly marks the northern boundary of the Aerodrome Traffic Zone. It is very common for traffic arriving from the north to be asked to report at the Golden Ball before entering the circuit.
The Golden Ball monument is atop the mausoleum next to West Wycombe House on Lord Dashwood's Estate; the site of the origin of the Hell Fire Club of Great Britain. It is certainly worth visiting this and the caves underneath which are extensive to say the least, but bring a torch! All this in a little village unspoilt save the thunder of juggernauts along the A40.
After leaving Princes Risborough en route to the airfield the Golden Ball will be seen on the top of the small hill in the centre of the valley you will follow. The Aerodrome Traffic Zone is just beyond the Golden Ball which is why ATC often ask you to report passing here.