>>>I can usually solve this puzzle in a few minutes by inspection but from time to time I encounter a string that stumps me. "VACTOR" got me sufficiently annoyed that I decided to brute-force it.
>
>>A better approach would've been to just ask here. I think the word's "vortac".
>>
>You must be a pilot!

I know the word since I was a kid, from reading about airplanes in encyclopedias. I'm a FlightSim junkie, though (been using it since it came out for the Apple II).

How about you? You knew the word's meaning right away. Are you a pilot?

Alex