If you descend from FL290 to 11,000 without resetting your altimeter, how will it affect your altitude reading?

When descending from FL290 (Flight Level 290, approximately 29,000 feet) to 11,000 feet without resetting your altimeter, the readings you will see can be heavily influenced by the local altimeter setting. The altimeter relies on the atmospheric pressure at your location to convert that pressure into an altitude reading. If the altimeter setting is not adjusted to reflect the local pressure, the altimeter may provide an inaccurate altitude indication.

As atmospheric pressure changes, typically due to weather conditions and altitude, not adjusting the altimeter could lead to a scenario where it displays a measurement that does not accurately represent your true altitude. Therefore, the correct reading of your altitude while descending would indeed depend on the local altimeter setting at the time of your descent. This means that if the atmospheric pressure differs significantly from standard pressure (which is 29.92 inHg or 1013.25 hPa), your altitude reading could be incorrect.

This understanding highlights the importance of setting your altimeter correctly upon entering a new weather region, especially when flying at lower altitudes where terrain proximity becomes a critical factor for safety.