The objectives of demonstrating an accelerated stall are to determine the stall characteristics of the aeroplane, experience stalls at speeds greater than the +1G stall speed, and develop the ability to instinctively recover at the onset. At the same gross weight, configuration, centre of gravity location, power setting, and environmental conditions, a given aircraft consistently stalls at the same indicated airspeed provided the aeroplane is at +1G.
The accelerated stall would most frequently occur inadvertently during improperly executed turns, stall and spin recoveries, pullouts from steep dives, or when overshooting a base to final turn. An accelerated stall is typically demonstrated during steep turns.
It is important to be familiar with Va, how it relates to accelerated stalls, and how it changes depending on the aeroplane’s weight. Va is the maximum speed at which the maximum positive design load limit can be imposed either by gusts or full one-sided deflection with one control surface without causing structural damage. Performing accelerated stalls at or below VA allows the aeroplane to reach the critical AOA, which unloads the wing before it reaches the load limit. At speeds above VA, the wing can reach the design load limit at an AOA less than the critical AOA. This means it is possible to damage the aeroplane before reaching the critical AOA and an accelerated stall. Knowing what Va is for the weight of the airplane being flown is critical to prevent exceeding the load limit of the airplane during the manoeuvre.
How to fly the manoeuvre:
1.) HASELL Checks
2.) Start at straight and level flight, at or below Va
3.) Roll the aeroplane into a level, co-ordinated 45 degree angle-of-bank turn (left or right)
4.) Increase back pressure on the control column until stall onset
5.) Recover using standard stall recovery technique
Points to consider:
1.) Onset of the stall will occur at higher-than-normal airspeed
2.) Onset of the stall will likely occur at lower-than-usual pitch attitude
3.) Avoid practising this manoeuvre with flaps extended due to lower design G load limitations
4.) Rudder co-ordination must be emphasised as there is the potential to enter into a spin
An aeroplane typically stalls during a level, coordinated turn similar to the way it does in wings level flight, except that the stall buffet can be sharper. If the turn is coordinated at the time of the stall, the aircraft’s nose pitches just as it does in a wings level stall since both wings will tend to stall nearly simultaneously. If the aeroplane is not properly coordinated at the time of stall, the stall behavior may include a change in bank angle until the AOA has been reduced. It is important to take recovery action at the first indication of a stall.