Issue with the Flights Climb measure in the Fitness/Activity app

Hi there

Please try this

Clear the Sensor Port

The barometric altimeter relies on a tiny air vent hole to measure atmospheric pressure.

• Locate the small speaker and mic/sensor vents on the side of your Apple Watch Series 8.
• Look for lint, dirt, sweat, or water blockage.
• Gently rinse the watch under warm, low-pressure tap water and dry it with a lint-free cloth. Do not insert any sharp objects into the sensor holes

2. Reset Your Fitness Calibration Data

Corrupted calibration profiles can throw off data translation. Resetting this forces the watch to relearn your stride and motion baseline: 

1. Open the Watch app on your paired iPhone.
2. Navigate to the My Watch tab and select Privacy.
3. Tap Reset Fitness Calibration Data.
4. To establish fresh, accurate data, go outside to a flat area with good GPS reception, open the watch's Workout app, and complete a 20-minute Outdoor Walk or Run at your normal pace. 

Thank you WheelieNick. Your tip(s) gave me a better insight into how the watch works.

I will try these tips and see how my watch performs after the cleaning and the calibration data reset.