If flying into an area of lower pressure without resetting the altimeter, true altitude would be higher or lower?

• A. Higher
• B. Lower
• C. The same
• D. Indeterminate

Answer: (B)

Altimeters translate ambient pressure into an altitude reading using the current sea‑level pressure reference. If you fly into an area where the local sea‑level pressure is lower and you don’t reset the altimeter, the instrument still uses the higher, old pressure reference. Lower pressure at your actual height means the pressure you’re seeing corresponds to a higher altitude on the altimeter’s scale, so the indicated altitude becomes higher than your real altitude. In other words, your true altitude is lower than what the altimeter shows. This is the classic high-to-low scenario: the altimeter over-reads, making you lower than it indicates.