Section 9, Lesson 1
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Vx and Vy

Vx and Vy

Vx and Vy are two different climb speeds that are common in light airplane operations. Climbing at Vx creates the most altitude gain in a given distance (therefore the best angle of climb), and Vy creates the most altitude gain in a given time (therefore the best rate of climb). Pilots need to understand when it is appropriate to use each.

Lesson Notes

Understanding Vx and Vy is important, and often a difficult concept for students. Remember that the difference between the two is whether you are gaining altitude in the least amount of time (Vy) or distance (Vx). So, if you’re trying to climb above a cloud, mountain, tree, and so forth you want to use Vx. If you’re trying to get up to cooler air the fastest, or climb through a haze layer you want to climb at Vy.

Pilots, and especially airplane owners, may opt to climb out at a speed a bit higher than Vy in order to increase cooling airflow across the engine. There is nothing wrong with this, and in fact it is usually preferable. It also gives the pilot better visibility over the nose to look for traffic.

Additional Resources

Flashcard Questions

If a pilot needs to gain the most altitude in a given time, which speed should they climb at?

If a pilot needs to clear obstacles in a given distance, which speed should they climb at?

Which speed is higher, Vx or Vy?

While out flying, you notice that when you start from cruise flight, you can climb much steeper at 55 knots than you
can at 65 knots. 65 knots is your published Vx climb speed. Why is this the case?

Why might some pilots want to climb a little faster than Vy under normal conditions?