bob@tinman.cis.ohio-state.edu (Bob Sutterfield) (06/30/89)
Yesterday afternoon was the first blue-sky day in months, and it would have been both criminal and immoral to spend the day in the office, let alone on the ground. So I took an officemate for his first light aircraft ride, which he generally enjoyed. In the car on the way home we discussed more specifics about the contents of the panel. Why, he wondered, are all radio frequency selectors knobs (often concentric, sometimes with different meanings when they're pulled out a notch) rather than keypads? My best answer was "to save panel acreage", which is a premium commodity in better-equipped small aircraft. However, it seems that even in higher-priced systems for larger panels like the new Honeywell gizmo box that I see advertised in Flying, frequency selection is still accomplished with concentric knobs. Keypads don't seem to be used until you get into LORAN-coupled moving map displays, where you need to type in intersections, waypoints, etc. and mere knobs wouldn't suffice. And some of those aren't intended to fit into the panel, anyway - the "console" has a cable and rests on your lap. So is panel acreage the only reason? Or are there other user interface considerations that override the apparent superiority of a general-purpose keypad over lots of specific knobs?