Helicopter Flight Information
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Helicopter Flight Information |
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Critical Wind Azimuth We were all taught about the four factors relative to LTE (left quartering headwind, left crosswind, tailwind, and the loss of translational lift), but were you aware of the "Critical Wind Azimuth"? I have only seen this in the Bell POH. Incidentally, the POH indicates that it is important at high altitude; but I can assure you that it is more important than that. It is important to note that this is relative to the direction of rotor rotation. As a demonstration, choose a runway or other safe approach path to a safe area where you can make an approach from either direction with a direct left and right crosswind. You will see that if you take the wind of the left, the aircraft will be significantly easier to control than if you take the wind off the right. If you make your approach with the wind anywhere in the Critical Wind Azimuth, you will notice the aircraft is significantly harder to control than with the wind in any of the remainder of the disk. Often pilots get caught off guard by this one. If you are in an OGE hover and you turn into this wind condition you will know it. It will be far worse if you are in a right pedal turn, and worse even still if your altitude is low. The helicopter will become difficult to control, and the best recovery will be to lower the nose and fly free of this condition just as you would from settling with power. Lowering the collective also helps. What ever you do, don't increase collective pitch. Keep in mind that this diagram depicts a helicopter with a counterclockwise rotor rotation.
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