SEDAYUBET After spending some time looking at champion guides you will likely get a pretty good feeling for some of the key items you should be buying on a regular basis. It's tough to buy something that will be outdated in just a few months, but there's always new gear just beyond the horizon -- you can't put off a purchase forever. Stacks are sections of airspace where inbound aircraft will normally use the pattern closest to their arrival route. Inbound aircraft to London Heathrow Airport typically follow one of several Standard Arrival Routes (STARs). Aircraft hold between 7,000 and 15,000 feet (2,134 and 4,572 m) at 1,000-foot intervals. Each stack descends in 1,000 feet (305 m) intervals from 16,000 feet (4,877 m) down to 8,000 feet (2,438 m). The Bovingdon stack is for arrivals from the northwest. It extends above the village of Bovingdon and the town of Chesham, and uses the VOR BNN ("Bovingdon"), which is situated on the former RAF Bovingdon airfield.|Chaudhary Sardar Khan