Ch 09.qxd 8/25/04 11:32 AM Page 9-4 Approach the tive pitch to minimize bobbing. If it becomes obvious that continued water taxi could lead to a serious problem, lift the helicopter off and reassess the situation. It might be possible to land in an area that does not contain the same conditions.  height/velocity diagram, reducing the probability of a successful autorotation in the event of an engine failure. Also, be aware of possible restricted visibility during takeoff from water spray produced by the rotors. To help alleviate these problem areas, as the helicopter begins to move forward, use reference points some distance in front of the helicopter. When hovering over or taxiing on water, movement of the helicopter may be difficult to judge. The rippling effect of the water from the downwash makes it appear as if the helicopter is moving in one direction when it is in fact stationary or even moving in the opposite direction. To maintain a fixed position or maintain a straight course while taxiing and hovering, use a fixed reference such as the bank or a stationary object in the water. When reference points are not available, judge movement by swirls, burbles, or slicks seen around the floats.  Hovering a helicopter over open water can create deceptive sensations. Without a reference point, extensive or rapid helicopter movements may go unnoticed. Very smooth and very rough water aggravate this situation. The most desirable water conditions are moderate ripples from a light breeze. An odd sensation, similar to vertigo, is sometimes produced by the concentric outward ripples resulting from the rotorwash, and pilots must keep their eyes moving and avoid staring at any particular spot. The inexperienced pilot may choose to initiate a slight forward movement when taking off into or landing from a hover. This guards against undesirable backward or sideward drift during takeoff or landing. With smooth water conditions, the usual tendency is to hover too high because the outward-flowing ripples from the rotorwash gives the pilot the sensation of being in a bowl and descending.  Over water, ground effect is reduced from the absorp- tion of energy in the downwash. This increases the power required to hover and with other factors may exceed the power available. When this occurs, perform a slow taxi to a takeoff to take advantage of the translational lift produced from the forward motion. Remember, translational lift is also affected by any wind that is present. Apply sufficient collective pitch to keep the floats riding high or skimming the surface. While skimming the surface, float drag increases rapidly, and the takeoff must be executed promptly since a further increase in speed, with the floats plowing in the water, is likely to exceed the limit of aft cyclic control or cause the floats to tuck under the water. The speed at which the floats tuck under is the maximum forward speed that can be attained and is determined by the load and attitude of the helicopter. Never lower the collective during this procedure because doing so could bury the nose of the floats in the water and possibly capsize the helicopter. Pilots performing glassy water landings may experi- ence some difficulty in determining their altitude above the surface. The recommended procedure is to continue an approach to the surface with a slow rate of descent until making contact, avoiding any attempt to hover. The helicopter’s downwash creates a disturbance in the water as concentric ripples moving away from the helicopter. Although this provides the pilot with a visual reference, it may also cause the sensation of moving backwards or descending rapidly. A natural tendency is to apply too much collective pitch in an attempt to halt the perceived descent. To overcome the effects of these visual illusions, avoid staring at the water near the helicopter and maintain forward and downward movement until contacting the water. When making approaches to a landing on a large body of water when land areas or other fixed objects are not visible, occasionally glance to either side of the horizon to avoid stare-fixation. Another technique some pilots use when fixed objects are not available, and the water is glassy, is to make a low pass over the area to create a disturbance on the surface. This disturbance remains for a while giving the pilot a reference to help determine distance.  When landing on water with a slight chop, bring the helicopter to a hover and descend vertically with no A normal takeoff from a hover over water is similar to the same type of takeoff over a hard surface. A common problem is poor judgment of altitude and rate of acceleration, which causes the pilot to increase speed without an increase in altitude. This causes the helicopter to enter the high speed portion of the The preferred method for taking off from water is to move forward into translational lift without pausing to hover after leaving the water. This type of takeoff is similar to a normal takeoff from the surface.  A float equipped helicopter can perform a normal takeoff from a hover or directly from the water. If there is insufficient power available for a normal takeoff, a running takeoff from a slow forward taxi may be an option. However, remember that water creates drag, so with insufficient power, a running takeoff may not be possible either.  TAKEOFF 9-4 LANDING