3 times your height to loose minus ten miles if theres a headwind, plus ten if theres a tailwind. but
always add an extra 5 miles to this as a safety net and to slow down and set up prior to intercepting approach, thats very important, theres nothing worse than hitting the loc at 250 knots 1000 ft high and clean. done it loads and it aint worth for the extra 1 minute 20 seconds you save.
