What is the difference between a fly-by fix and a fly-over fix?

What is the difference between a fly-by fix and a fly-over fix?

• A. A fly-by fix allows turning before reaching the fix; a fly-over fix requires crossing the fix before turning.
• B. A fly-by fix requires crossing; fly-over allows turning beforehand.
• C. Fly-by fix is only for VORs; fly-over is only for GPS.
• D. Fly-by is for altitudes; fly-over is for speeds.

Answer: (A)

The main idea is when you start your turn relative to the fix. With a fly-by fix, you begin turning toward the next leg before you reach the fix, using a calculated lead point so you smoothly roll onto the new course without stopping over the fix. This lets you stay on a continuous path and typically saves distance and time. With a fly-over fix, you must cross directly over the fix first, then start the turn onto the next leg after you’ve passed that point. You’re effectively required to overfly the fix before changing direction. So the distinction is about turn timing: turning before reaching the fix versus turning only after crossing it. This concept isn’t about which navigation aid is used or about altitude or speed.

The main idea is when you start your turn relative to the fix. With a fly-by fix, you begin turning toward the next leg before you reach the fix, using a calculated lead point so you smoothly roll onto the new course without stopping over the fix. This lets you stay on a continuous path and typically saves distance and time.

With a fly-over fix, you must cross directly over the fix first, then start the turn onto the next leg after you’ve passed that point. You’re effectively required to overfly the fix before changing direction.

So the distinction is about turn timing: turning before reaching the fix versus turning only after crossing it. This concept isn’t about which navigation aid is used or about altitude or speed.