zOwie Omega Discussion Forum

: my omega aqua terra loses about four minutes
: every month, is this normal?

No, this is not normal. With this kind of accuracy, I expect you to have one of the automatic versions of the aqua terra. All ATs are COSC cretified.

What does it mean to be COSC certified? Derek Ziglar explains it below:

"The first need for very accurate timepieces came from ships needing precision timekeeping to allow precise celestial navigation. The term chronometer came in to use to describe timepieces accurate enough for ship navigation. In 1973, the Controle Officiel Suisse des Chronometeres (COSC) came in to existence as the official testing and certification control board.

Now, only a watch whose movement has been certified by COSC can be called a chronometer. For a typical men's-sized mechanical watch movement, it must have stayed within -4 to +6 seconds of variation per day during the COSC measurement at various temperatures and positions.

COSC also certifies quartz movements (their standard is +/-0.2 second per day for these). But since quartz movements are inherently very accurate and suffer little to no variation based on position or normal temperature ranges, certification is much less significant to buyers of quartz movement watches. Almost no watchmakers go to the expense to have COSC certify their quartz movements.

A chronometer certificate is not a guarantee of future accuracy. Watch movements that have been certified can get out of adjustment and perform poorly. Movements that were not certified may still exceed the COSC standards--the manufacturer may simply have simply chosen to bypass the expense of the certification process."

Your watch seems to be losing over 7 seconds (-7) a day, this means that it is well out of COSC spec and you need to send it back for repairs or for a servicing. If the watch is still within the co-axial warranty period, this will be done for free.

: what is the
: acceptable amount of +/- minutes i should
: expect from this watch?

Chronometers run -4/+6 seconds a day => -2/+3 minutes a month (slow by 2 and fast by 3).