Slope landings

October 4, 2012 by Tim McAdams

Not every surface a helicopter lands on is perfectly level. So a slope landing is a maneuver that helicopter pilots need to know how to perform. The first step is bringing the helicopter to a stabilized hover into the wind and insure the ground is stable (for example, no loose gravel). Care must be taken when making pedal turns to avoid getting the tail rotor too close to ground. In the case of the ground sloping laterally, the pilot should slowly lower the collective until the upslope skid contacts the ground. At this point, apply lateral cyclic to firmly seat the skid into the slope. Maintain heading control with the pedals to prevent the skid from pivoting. Holding the upslope skid against the slope with cyclic, continue slowly lowering the other skid a little at a time with the collective. As the pilot continues lowering the collective, more lateral cyclic is required to hold the upslope skid firmly against the ground. If the pilot runs out of lateral cyclic prior to the downslope skid becoming firmly seated on the ground, then the slope is too steep and the landing should be aborted. When performing slope landings pilots need to be aware of the increased risk of dynamic roll over and, with a semi-rigid rotor system, mast bumping.

Once both skids are securely down, some instructors recommend centering the cyclic after the collective reaches flat pitch in order to have more clearance with the rotor system on the upslope side, others recommend keeping it displaced into the slope for the duration of the landing to prevent any sliding.

Lifting off a slope is essentially the reverse procedure. Raising the downslope skid with collective while moving the cyclic back neutral. Once the helicopter is level, lift off the slope. The pilot should keep in mind if a lot of weight is off loaded the CG might have changed enough to shift the cyclic neutral point, which could compromise a safe lift off.

3 Responses to “Slope landings”

  1. GM Poland Says:

    Every Take off and landing in a helicopter is a slope technique. Think About it. All Helicopters are subject to a rotational force that is corrected by a tail rotor. Causes a lateral drift. Compensated for in Contol Rigging. Result is a unlevel hover attitude lateraly.

  2. J Harris Says:

    Good point, GM Poland. Fuel and passenger load conditions can really change the attitude a lot, too.

  3. Kent Says:

    Most rotor head designs other than semi-rigid will be stressed if cyclic is left displaced after collective is lowered. Once the collective is lowered all the way down there is minimal, if any, thrust produced by the main rotor and it is pointless to leave the cyclic positioned into the slope. In fully articulated and rigid rotor head designs it is a no-no.

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