Which is true about maneuvering speed?

What maneuvering speed protects

Maneuvering speed is the speed at or below which the wing stalls before the airplane can be loaded past its limit load. Above it, an abrupt full pull or a strong gust can overstress the airplane before the wing stalls. Below it, the stall comes first and unloads the wing. That's also why VA isn't marked on the airspeed indicator. The number moves with weight.

Why weight changes it

At any given airspeed, a heavier airplane flies at a higher angle of attack to make the extra lift it needs. That puts it closer to its critical angle of attack, and it's also why its stalling speed is higher. A positive pitch input or turbulence abruptly increases the angle of attack, and with it the G load. Because the heavier airplane starts closer to the critical angle of attack, it can fly faster and still stall before exceeding its load limit.

A lighter airplane flies at a lower angle of attack at the same airspeed, farther from its critical angle of attack. The same input can push the load past the limit before the wing stalls. Flying slower keeps the angle of attack higher, so the airplane stalls before exceeding its load limit. So maneuvering speed goes down as weight goes down, and up as stalling speed goes up.

To find VA at a lighter weight, multiply the published VA by the square root of the actual weight divided by the max gross weight. For an airplane with a VA of 105 knots at 2,550 pounds, flown at 2,200 pounds, that works out to about 98 knots. The rule of thumb gets you close: reduce VA by about half the percentage you're under gross.

VA, VO and your POH

Many POHs, especially for older trainers, publish one VA at max gross weight. Some list it at two or three weights. Airplanes certified more recently list VO, the maximum operating maneuvering speed, an operating limitation set no higher than the speed where the airplane stalls before exceeding its limit load.

Strictly speaking, VA is a design speed the manufacturer picks, and it doesn't have to change with weight. The speed that does is the one that keeps the stall ahead of the limit load. The FAA's 2011 bulletin on maneuvering speed says VA decreases as weight decreases, and that's the speed this quiz is about.

What VA doesn't protect against

Below VA, you can move a single control, one time, to full deflection, on one axis, in smooth air. The 2001 crash of American Airlines Flight 587 shows what can happen when a pilot goes beyond that. The A300 flew into wake turbulence from a 747 that had departed ahead of it. The first officer answered with full rudder one way, then the other, several times. Each reversal swung the airplane into a bigger sideslip, and the loads on the vertical stabilizer climbed past its ultimate design strength until it separated. The airplane was well below its maneuvering speed the whole time. The FAA issued SAIB CE-11-17 in 2011 to clear up the misunderstanding. It warns against reversing a control, and against full inputs on more than one control at once, even below VA.

What about stall speed in a turn?

Stalling speed rises in a turn because the load factor rises. That higher number is the accelerated stall speed. VA is figured from the 1G stall speed at a given weight, so it doesn't change in the middle of a turn.