The Myth of Maneuvering Speed

Maneuvering Speed Myths

Most pilots and flight instructors understand VA as the maximum speed at which the airplane will stall prior to structural damage, and that full deflection of the flight controls at or below this speed poses no risk to the airplane. This is a dangerous assumption and it is simply untrue.

VA is defined as design maneuvering speed. It is an arbitrary number chosen by the aircraft manufacturer and is used to design the empennage.

14 CFR Parts 23 and 25 govern the certification of light planes and transport-category airplanes and requires that VA is no less than VS√(n) and no greater than VC (design cruise speed). For the math-minded folks, it looks like this:

VS√(n) ≤ VA ≤ VC

According to the law, the lowest speed that you can possibly pick for VA is VS√(n) — the maximum theoretical speed at which a stall occurs before structural damage. And VA can be as fast as cruise speed. That seems like a pretty wide range!

There is absolutely no protection guaranteed by flying at or below VA, and pilots are cautioned about this in FAA Advisory Circular 23-19A:

VA should not be interpreted as a speed that would permit the pilot unrestricted flight-control movement without exceeding airplane structural limits, nor should it be interpreted as a gust penetration speed.

Only if VA = VS √(n) will the airplane stall in a nose-up pitching maneuver at, or near, limit load factor. For airplanes where VA > VS√(n), the pilot would have to check the maneuver; otherwise the airplane would exceed the limit load factor.

So it is true in some cases that VA provides load-limit protection, but it’s important to realize that it is not required for Part 23 and Part 25 certified aircraft, and the same goes for light sport aircraft. But when it comes to structural limitations in practice, just don’t push it, regardless of speed.


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About the author
Pat Flannigan is a professional pilot and aviation blogger. He has been flying for fifteen years and is currently working as an airline pilot in the United States.

3 Replies to The Myth of Maneuvering Speed

  1. Steve Pomroy says:

    It’s nice to see this point finally making it’s rounds through the aviation community! Good job!

    An expanded look at Va can also be found at the FlightWriter blog: http://www.flightwriter.com/2010/09/va-not-bad-speed-just-misunderstood.html and http://www.flightwriter.com/2010/09/va-not-bad-speed-just-misunderstood_27.html.

    Cheers!

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