We draw the line of the route unto the chart. Ten minutes after making a position report we push "Hold" on the FMS and INS heads. Then we plot the Lat/Long position of the FMS position (INS triple mix) on the chart and compare it to the line we drew. We also write the Lat/Long positions of each INS unto the chart. If one INS has taken "a walk" we could deselect it from the triple mix mode fed to the FMS which steers the autopilot. We also note Temp/Wind and FLight Level data;...keeping it as simple as possible.
[ 10 August 2001: Message edited by: GlueBall ]