You are planning to fly across a mountain range. The chart recommends a minimum safe altitude of 12 000 feet above MSL.
The air mass you will be flying through is an average 10 Degree Celsius warmer than ISA.
Your altimeter is set to 1023 hPa (QNH of a nearby airport at nearly sea level). What altitude will the altimeter show when you have reached the recommended minimum altitude?
11520 feet
11790 feet
11250 feet
12210 feet
Solution
The difference in temperature is 1% per 2,5 degrees variation from ISA.
10/2,5 =4%
4%X12 000 = 0,04X12000=480
Then you subtract the answer of the temperature difference to the altitude of 12 000
12000-480= 11520 feet
