It's supposed to be 1000 knots when above 60k ft. Due to laziness/cost, many GPS modules take it to mean any speed above 60k feet. Here's a list of ones that wi

It's supposed to be 1000 knots when above 60k ft. Due to laziness/cost, many GPS modules take it to mean any speed above 60k feet. Here's a list of ones that will work above 60k feet: http://showcase.netins.net/web/wallio/GPSrcvrsvs60kft.htm http://showcase.netins.net/web/wallio/GPSrcvrsvs60kft.htm