Calibrating the altimeter

Some (many?) people think that their Instinct is faulty because the elevation it displays is often wrong by hundreds of feet. I now understand this. I think Garmin could have handled this differently, but they didn't.

The story is that the Instict uses a barometric sensor to calculate the displayed elevation. That's right and we know what that means. Pressure can change from day to day (and from hour to hour) due to changes in the weather. Any barometric altimeter needs to be calibrated regularly and frequently. Before GPS was in existence, pilots did this every time they took off, using the known elevation of the airport to set the elevation.

I hear you already. "The Instinct has GPS, why can't it get this right?" Because Garmin made some questionable design decisions, that's why. My guess is that they adopted a policy of never activating the GPS unless the user explicitly asks for it. My guess is this is an effort to extend battery life (and they did a good job of that). "Why not calibrate automatically once a day." is something I have asked. Who knows. They don't, so your elevation just drifts around with the weather.

I have tried tricking it into doing a calibration by starting a track, letting it get a GPS lock, and then expecting the elevation to get set. That does not work.

You can ask for a calibration!

• Hold down "menu" (center left) until a menu appears.
• Use "down" (lower left) to get to settings
• Press "gps" (upper right) to enter settings
• Use "down" (lower left) to get to "sensors and accessories"
• Press "gps" (upper right) to enter "sensors and accessories"
• Use "down" (lower left) to get to "altimeter"
• Press "gps" (upper right) to enter "altimeter"
• you won't need to use "down" (lower left) to get to "Calibrate", or shouldn't.
• Press "gps" (upper right) to enter "Calibrate"
• Use "down" (lower left) to get to "Use GPS"
• Press "gps" (upper right) to do the calibration
• wait for calibration to get and dislay elevation
• Press "gps" (upper right) to "make that so"
• Use "back" (lower right) several times to get back to the clock face

Obviously you should do this someplace with a clear view of the sky.

Along the way, you may see "Auto Cal" and get excited (like I did). This is not what you hope it is. It tells it to calibrate the altimeter whenever you turn on the GPS for some other reason (and I have tried this and found that it just doesn't work).

There is an option to calibrate using DEM, and like me you ask what the heck this is. It will calibrate using the "digital elevation model" if you have the Instinct connected to the Connect app running on your phone. Why didn't Garmin program it to do this automatically, like whenever you are connected to the Connect app and the elevation is over 24 hours out of date or some such.

They also have an option to "input the current elevation manually". I can only imagine what a pain that would be, and once you have plowed your way that far in the menu system, you may as well just use GPS.