Richard Meredith-Hardy, CIMA President
Timing at finish lines
8.4 TIMING IN GATES
Crossing time will be taken from the oldest point defining the track segment that crosses the gate. This is the track point just before crossing the gate.
S10 An6 2005 6.3.3 said A Start line, IP or gate time is taken from the fix immediately before the line is crossed. A Finish line or FP time is taken from the fix immediately after the line is crossed.
I can't remember exactly when this got changed, but nobody seems to have noticed the repacement text in 8.4 introduced a significant problem.
Whilst in respect of start lines the new text has the same meaning as the old text, the new text omits to consider how times should be taken at finish lines.
Besides being obviously wrong to have a finish time taken at any point before crossing a finish line, if the previous fix was long before the finish line then this could have a very significant effect on the resulting performance.
Consider a speed record attempt over a 15 Km course for example. Pilot has a logger recording at 1 second intervals, start line fix is the one before the start line, the logger records another fix, and then the pilot covers the gps antenna until he crosses the finish line 15 Km later, and then lets it start recording again. If the fix before the finish line is considered the finish time, then the 15 Km would be considered to have been flown in 1 sec, which computes to a speed of 54,000 Km/h.