Altimeter setting drops 0.25 inHg, pressure altitude change?

Altimeter setting drops 0.25 inHg, pressure altitude change?

• A. 100 feet
• B. 1,000 feet
• C. 200 feet
• D. 250 feet

Answer: (D)

Alimeter readings shift with the setting you dial in, because the instrument compares ambient pressure to a reference sea-level pressure you input. The quick rule is that about 1 inHg change in the setting corresponds to roughly 1000 feet of altitude change. If you lower the setting by 0.25 inHg, the altimeter will indicate you’re higher by about a quarter of that 1000-foot rise. So the pressure altitude increases by roughly 250 feet. If you had raised the setting by 0.25 inHg, it would indicate about 250 feet lower. This is a handy mental math shortcut for rapid planning and checks.

Alimeter readings shift with the setting you dial in, because the instrument compares ambient pressure to a reference sea-level pressure you input. The quick rule is that about 1 inHg change in the setting corresponds to roughly 1000 feet of altitude change. If you lower the setting by 0.25 inHg, the altimeter will indicate you’re higher by about a quarter of that 1000-foot rise. So the pressure altitude increases by roughly 250 feet. If you had raised the setting by 0.25 inHg, it would indicate about 250 feet lower. This is a handy mental math shortcut for rapid planning and checks.