A typically daft hold. OK if using some system overlay which eliminates slant range errors, but as published, an aircraft with basic TACAN holding at FL80 on a low pressure day would actually see a range of about 3.4 miles when overhead the 3d fix..... If the pilot waited until he/she saw 3.0 miles before turning, he would in fact be at 0.5d beyond the fix, thanks to slant range error......
Why so high / close?
The old Valley Point Alpha is perhaps a legacy of Gnat days when it could set up as a TACAN offset point as 220/14, giving 'pseudo-overhead' indications at the fix - hence it would be possible to make sector entries? Although anyone risking such a comment in those days would probably have found themselves on a one-way train to Oakington PDQ!
I have an old 'Jet Instrument Approach Chart' for Valley, dated 5 Aug 1954. Initial approach to overhead the CR DF ('Homer' on 110.98 Mc/s) not below 12000 ft. Track outbound on 020° to 'half initial approach altitude plus 2000 ft, then turn left and fly inbound to make good a track of 190°. Then a 'check altitude' of 2000 ft followed by a minimum approach altitude of 600 ft.... Variation was 11°W, so it must have been quite sporting trying to get in on RW 14 on minima.....
