In a scenario where you are 20 NM from a fix, flying at 120 KTS ground speed, starting at 10,000 ft and must cross at 6,000 ft, how many minutes will it take to reach the fix?

In a scenario where you are 20 NM from a fix, flying at 120 KTS ground speed, starting at 10,000 ft and must cross at 6,000 ft, how many minutes will it take to reach the fix?

• A. 8 minutes
• B. 12 minutes
• C. 10 minutes
• D. 15 minutes

Answer: (C)

The main idea is that flight time to a point depends on how far away you are and how fast you’re going over the ground. Time equals distance divided by speed. You’re 20 nautical miles from the fix and flying at 120 knots. 20 divided by 120 hours equals 1/6 hour, which is 10 minutes. You also start at 10,000 ft and must cross at 6,000 ft, so you’d descend 4,000 ft during this leg. Over 10 minutes, that’s an average descent rate of 400 ft per minute, which is a typical and feasible rate. The altitude constraint doesn’t change the time to reach the fix with the given speed and distance, it only defines the descent profile you’d need to satisfy to cross at the required altitude.

The main idea is that flight time to a point depends on how far away you are and how fast you’re going over the ground. Time equals distance divided by speed.

You’re 20 nautical miles from the fix and flying at 120 knots. 20 divided by 120 hours equals 1/6 hour, which is 10 minutes.

You also start at 10,000 ft and must cross at 6,000 ft, so you’d descend 4,000 ft during this leg. Over 10 minutes, that’s an average descent rate of 400 ft per minute, which is a typical and feasible rate. The altitude constraint doesn’t change the time to reach the fix with the given speed and distance, it only defines the descent profile you’d need to satisfy to cross at the required altitude.