2005-05-19 21:21 | fche blog flying how not to yam
One interesting glitch occurred during today’s extra-long Hope Air flight, which consisted of a nine-hour Toronto->London->Thunder Bay->Toronto triangle marathon.
Most major airports have a VOR navigational transmitter located nearby. Like an airport, each transmitter is given a unique name. These names are used for identifying waypoints along a flight route to a navigational computer like an airborne GPS receiver. Generally the names match up using a simple pattern: here are some Canadian ones.
| location | airport | VOR |
| London | CYXU | YXU |
| Toronto | CYYZ | YYZ |
| Thunder Bay | CYQT | YQT |
Sometimes they don’t:
| Kitchener | CYKF | YWT |
| Sault Ste. Marie | CYAM | SSM |
This afternoon, after dropping off our passengers at Thunder Bay, and just leaving to return home, I messed up entering the waypoint names into the new GPS on board. I entered “YAM” to refer to the VOR located near the Sault Ste. Marie airport. The GPS promptly drew a line that seemed to go roughly in the right direction. The lower graphical display started showing bizarre figures like 823894823h28m as an estimated en-route time. And neither agreed with our plain old VOR receiver for which direction to fly.
After a helpful controller chimed in and pointed out that perhaps we’re heading in the wrong direction (off by 30 degrees, getting farther away from land over Lake Superior), we finally figured out what was going on. YAM is wrong, SSM was the right name. The correct line came up drawn on the GPS, and all the various navigational instruments agreed. We thanked the controller for his timely assistance.
It turns out a VOR named YAM does exist in the world. It’s in Ivory Coast, in Africa. The GPS was eagerly guiding us 10000 miles away, across the continent and the atlantic ocean. Well, even without the controller, I am sure we would have figured it if we were to run out of fuel somewhere in Quebec.