The Breitling Watch Source Forums

As we all know COSC certification has a couple of qualifying requirements, and one of the main is AVERAGE daily rate of -4/+6 sec. How we would measure that ourselves manually is by comparing the time on our watch with a quartz or our mobile phone or some other means that could more accurately tell time. However we will not be monitoring our watches 24/7 but rather compare the time once a day or once every few hours. The words "AVERAGE DAILY RATE" set me thinking. For eg, If I set and sync the time at 12am on day 1, say I check the time once every 12 hours, the first 12 hours say lost 10 sec but the next 12 hours gained 11 sec. So the AVERAGE DAILY rate becomes only 1 sec gain. Does that mean that the watch is running within COSC specs as per definition? Because if I had checked the watch only once, which is 24 hours later at 12am the following day, I would have thought that the time had only gained 1 sec, without knowing that it had deviated 10 sec or 11 sec in between.. Or if I had checked the watch only once at 12pm, which was only 12 hours after the sync and saw the 10 sec gain, I would have thought that the watch was out of COSC specs...

The COSC institute has the necessary equipments to accurately measure all these including the AVERAGE DAILY RATE 24/7 for that 15 days. But for us, I guess we can only manually do it with the above methods. So if we encounter something like the above, is it considered within or out of COSC specs, given that the time gain at the end of 24 hours is only 1 sec, although it had deviated 10 sec in between? Sorry for the stupid question because I understand that there are other COSC requirements that might answer my question, but I am not exactly sure of what other requirements mean other than the average daily rate of -4/+6 sec.

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Breitling Chronomat 01 Limited Edition
Breitling Navitimer 01 46mm

Its a lot more detailed than just -4/+6. There are standards that specify how much a reading can vary from another reading.

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-RJ

The full specs are on the COSC website, but if it is within tolerances for a 24 hour period then it is within COSC specs. Given that testing is within controlled conditions the theoretical losses and gains within a 24 hour period wouldn't occur at the COSC, but in the real world regulation is all about compensating errors. A watch will run faster in some positions than others, it will run faster in some temperatures than others, it will run faster at some levels of power reserve than others, etc, etc, etc.

Regulation is intended to try and ensure that when all of those things come together over a reasonable period then the variance is acceptable, but if you take snapshot variations after the watch has been subjected to different conditions - timing it after 12 hours of active wear vs. 12 hours sitting on the night stand for example, then there may well be larger variances.