"Set Reference yes or no" What situations trigger this question on the Core?

[Mystro]

Since this is not in the manual, I thought I would like to get some observations on what and when the "Set Reference yes or no?" is triggered on your Core.??

[Caneda]

i.always after flying.
ii.when I donīt set a new reference for a long time (two weeks or so) - donīt know what triggers this.

[Jeff_C]

I concur with ii.

[Mr. Speed]

Mine asked me that after I drove from Illinois to Louisiana last week. Perhaps drastic changes in air pressure cause it to ask that question, just to make sure it's reading things properly. These Core's sure are dang smart watches.

[Geof3]

set reference is the sub setting for the reference barometric pressure that allows altitude to be calculated. I believe, if you change altitude rapidly, or have wide variations in altitude/pressure it will ask for this.

[Caneda]

Interesting thing...

From the Core manual:
"Changes in local weather conditions will affect altitude readings. If local weather changes often, it is advisable to reset the current altitude reference value frequently, preferably before starting your journey when the reference values are available. If local weather is stable, you do not need to set reference values."

Same chapter, from Lumi manual (better one):
"Changes in local weather conditions will affect altitude readings. If local weather changes often, it is advisable to frequently reset the local reference altitude value, preferably before starting your journey and when an altitude reference value is available. If local weather is stable, the local altitude reference value can be set just once a day."

Considering that Lumi is similar to Core, everyone were aware of this? Setting once a day! I wasn't. Or aren't they similar?

[Geof3]

The altitude reference is a non issue day to day. This is only if you are doing something that requires altitude tracking or you are using your logbook and want it to be as accurate as possible. The barometer is the setting that varies. This will change if the weather is off or otherwise.

Technically the barometer is affected by altitude, but the altitude must be set and reset at given intervals to be certain it is correct as it only fluctuates based on the barometer. So, if the barometer is changing fast, the altitude with not change accurately based on your ascent or descent rate. Thus a reference point must be picked at a known altitude on a map. Usually this is good to start at trailheads, trail splits etc. Usually the altitudes are known and the Core (or any alt) can be calibrated. I personally use landmarks, and if the situation is mellow I might simply do the trailhead and the summit, or turn around point. Just depends. This rule applies for all barometric based altimeters whether digital or analog.

With regard to the original post, it may be that the fluctuations were outside of the Core's 'normal' limits, thus requiring a reference to be set. It is also possible you simply pushed a button, or it got pushed by your wrist for too long. I lock my Core day to day.