When flying into lower temperature, the true altitude is relative to the altimeter: higher or lower?

• A. Higher
• B. Lower
• C. Same
• D. Cannot determine

Answer: (B)

Cold air makes pressure surfaces sit closer to the ground, and the altimeter is calibrated for standard (ISA) conditions. When you move into air that’s colder than standard, the pressure you sense at a given true height corresponds to a higher altitude on the standard scale. In other words, for the same pressure reading, you’re actually lower than the indicated altitude. So the true altitude is lower than what the altimeter shows. This is why cold temperature can cause a higher indicated altitude than your actual height above the terrain, requiring appropriate corrections to maintain safe clearance.