The accuracy of manual timekeeping in track and field


This comes up a lot, so I thought I would share some information with you. The recent prompt is a post I saw on another excellent website called but as a timekeeper I am often told my times are wrong by coaches, parents or athletes. We all do.

To be honest, I used to do the same thing. I would time the race and then be incredulous when the official time was 0.3-0.4 seconds slower. Unbelievable. I didn’t assume I was right though, I trained to be a timekeeper to find out. And I did find out. That I was wrong.

There a few things you need to understand as fundamentals. First there are generally two people timing each athlete. If there are only a handful of timekeepers, the chief timekeeper (usually the most experienced timekeeper to boot) will time not only first place, but all the other places as well as a double check, or incase someone misses a time for some reason. (We’re only human).

Second, timekeepers time positions, not lanes. For example, i will be given third place and that’s the only time I take.

Third, the timekeeper positions are elevated and perfectly aligned to the finish line for a reason. The position is important to accuracy.

Fourth, timekeepers time to the flash of the gun, not the sound. Light travels faster than light.

Now, even if you know all that, here’s why you, your coach or your parent will time faster than the timekeeper.

Let’s say everyone starts their clock on the flash of the gun. The untrained person will anticipate the athlete crossing the line and prepare themselves, then at the exact moment the athlete breaks the plane, they stop the clock and look up triumphantly because of the personal best their athlete has just run. The timekeeper on the other hand is trained not to anticipate the crossing of the line, they react to the crossing of the line and then stop the watch. It sounds the same, but it isn’t. If you stand next to a timekeeper stand, you will hear the beep of the clock being stopped when the athlete is a few meters past the finish. That is because they are reacting to the athlete crossing the line and there is a reaction time.

So here is an example in numbers.

The gun flash goes off and everyone starts their watch, lets say at exactly the same time. However, because of reaction time, the time the watch is started is 0.5 seconds after the flash. The photo finish started immediately on the gun, because that’s how it works.

Usain runs his race and crosses the finish line. As he does so, the photo finish also stops the clock, and so does the coach. The timekeeper on the other hand stops his 0.5 seconds after Usain crosses the line. Usain is now 5 meters past the finish at this point.

So, here are the numbers.

0 seconds. Photo finish starts clock.

0.5 seconds. Timekeeper and coach starts clock.

10.00 seconds Usain crosses finish line. Photofinish clock stops. Coach clock stops.

10.50 seconds Timekeeper watch stops.

Times recorded in terms of elapsed time:

Photofinish time 10.00 – 0.00=10.00 seconds – “Nice run Usain”

Timekeeper time. 10.50 – 0.50 = 10.00 seconds. “Nice run Usain”

Coach time 10.00 – 0.50 = 9.50 seconds “Wow, world record Usain!”

So, reaction time at the start has to be the same as reaction time at the end. Reaction time of photo finish is 0 at both ends. Timekeeper is 0.50 at both ends. Coach is 0.50 at start and 0 at end, a 0.50 second reduction.

Next, for hand time, the accuracy is 0.1 second, not 0.01 as it is for photo finish. Therefore a 9.91 second run for Usain, would be recorded as 10.0. So the coach would record a 9.41 (because of his 0.5 send differential as well) and the timekeeper 10.0. Timekeeper must be an idiot, says coach/parent.

The final thing is that as well as being two timekeepers timing each position, there is the added point that other than for first place, which is the most experienced timekeeper anyway, there is an athlete ahead and behind. If the timekeeper of a particular placing was indeed 0.5 seconds slow, then the timekeeper of the place before and the place after would be hugely different and it would be obvious to all the timekeepers and the time would revert to the chief’s time.

So before you question the timekeepers ability, you should try it. Time against a photo finish if you have a chance. You will find (as I did initially) that preventing yourself from anticipating the runner crossing the line (especially if it is your own athlete) is a lot more difficult than it sounds.

And finally, remember that none of the officials get paid. They are giving up their time, not only to officiate, but to do all the training and everything else that goes with it. Think about that.

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