Exercise 24 - Advanced Take-Offs and Landings

GROUND SCHOOL POINTS

Flight Manual

  • Limitations,
  • Load and Density Altitude Performance Charts,
  • Vortex Ring

PREPARATORY INSTRUCTION

Aim

For the student to learn additional take-off and landing techniques for use under operational conditions.

Review

Motivation

Although the techniques learned in Exercises 9 and 12 are those that should continue to be used under optimum conditions, operational situations such as high all-up-weight, high density altitude, unfavourable wind conditions or obstacles close to the flight path, may dictate the use of advanced techniques. Another practical application is in conditions of restricted visibility, such as snow, dust or sand.

Airmanship

  • Lookout - obstacles
  • Aircraft limitations

Teaching Points

    1. No Hover Take-off
      1. Explain that this take-off can be usefully employed in conditions of blowing snow or where dust, sand or debris may cause a hazard should a normal take-off and departure be used.
      2. Describe the technique for carrying out a no hover take-off as follows:
        1. complete take-off checks, making sure that RPM is at the maximum take-off setting;
        2. make a careful all-round lookout;
        3. smoothly apply collective to initiate a vertical climb,use the cyclic to set the climb attitude when passing normal hover height; and
        4. adjust when clear of obscuring phenomena.
        5. Point out that since this type of take-off is not preceded by a hover check, it is doubly important to ensure that the aircraft is within weight and C of G limits and that there is sufficient power available for the intended departure.
    2. Cushion Take-off
      1. Point out that this type of departure is very economical in power required, since it involves making maximum use of the ground cushion until translational lift has been acquired. It does however, require a relatively flat departure path, free of obstacles. This technique is effective in circumstances where it is not possible to take-off into wind.
      2. Describe the technique for carrying out a cushion take-off as follows:
        1. carry out a hover check at a low hover in maximum ground effect facing into wind;
        2. lookout;
        3. initiate slow forward movement with cyclic;
        4. apply sufficient power to prevent sink;
        5. maintain gentle acceleration, staying in maximum ground effect; and
        6. as ground effect is lost and translational lift is acquired, select climb power and airspeed.
      3. Stress that in order for this type of take-off to be effective, all control movements must be gentle and progressive.
    3. Vertical or Towering Take-off
      1. Explain that this type of departure is ideal for circumstances where there are obstacles in the departure path. Depending on the height of the obstacles as this method involves the use of high power settings.
      2. Describe the technique for carrying out a vertical or towering take-off as follows:
        1. establish a low hover into wind, complete a power check and take-off checks;
        2. apply sufficient power to initiate and maintain a gentle vertical climb;
        3. ensure that the climb is vertical by reference to obstacles ahead and to the side of the helicopter;
        4. as the top of the obstacle is reached, check for a positive rate of climb, then ease the cyclic forward so that the aircraft moves forward and continues to climb; and
        5. as translational lift is attained, select climb attitude and apply climb power.
    4. No-Hover Landing
      1. Explain that this type of landing is useful in conditions where it is not desirable to approach to or hover, such as dust, powdery snow or turbulence. It requires less power than a normal approach to a hover.
      2. Describe the technique for carrying out a no-hover landing as follows:
        1. approach the selected landing spot as required;
        2. when the approach is almost completed, and groundspeed is close to zero, anticipate loss of translational lift applying sufficient power to minimize the rate of descent; and
        3. let the aircraft sink gently through the cushion onto the ground.
      3. Point out that this type of landing requires careful prior confirmation that the selected spot is suitable for landing.
    5. Run-On Landing
      1. Explain that this type of landing can be used in similar conditions as the no-hover landing. Although it requires less power to perform, a large, flat, smooth surface such as a runway is essential.
      2. Describe the technique for carrying out a run-on landing as follows:
        1. approach the selected landing area as required;
        2. as the approach is completed, run-on at slow walking pace;
        3. apply sufficient power to cushion landing; and
        4. after landing, maintain cyclic and collective positions until forward movement stops.
    6. Approaches

      Explain that in operational conditions, it is sometimes necessary to approach to land at an angle other than standard, as follows:

      1. Steep Approach
        1. This approach is for avoiding obstacles on the final approach path. Point out that apparent ground speed will be lower than normal and that more power will be required.
        2. Stress the need to maintain a low rate of descent due to the danger of vortex ring state, or insufficient power to prevent a hard landing.
      2. Shallow Approach
        1. Explain to the student that a shallow approach requires less power than a standard or steep approach. It should be employed when the approach path is free from obstacles and where conditions limit the power available, or where maximum power is available but inadequate for the use of standard techniques.
        2. Stress that care should be taken to avoid making the approach angle too shallow, i.e. flat. This requires high power settings and can lead to problems in decelerating to a hover, due to the possibility of the tail striking the ground.

Confirmation  

PRE-FLIGHT BRIEFING

AIR LESSON
    1. Review the standard take-off and departure. Note power required and compare, after demonstrating, with the following techniques:
      1. no-hover take-off and standard departure;
      2. cushion take-off; and
      3. towering take-off.
    2. Student practice.
    3. Review the standard approach to the hover into wind. Note power required and compare, after demonstrating with the following techniques:
      1. standard approach to a no-hover landing;
      2. standard approach to a run-on landing;
      3. steep approach to a no-hover landing;
      4. shallow approach to the hover; and
      5. shallow approach to a no-hover landing.
    4. Student practice.
    5. Demonstrate a flat approach (i.e. too shallow) and point out power required.

POST-FLIGHT DEBRIEFING

TIPS FOR INSTRUCTORS
    1. Introduce these techniques in a flat, clear training area initially. When the basic techniques have been mastered by the student, introduce obstacles and unfavourable wind conditions. Limited power situations can be achieved by loading the helicopter or by limiting the amount of power the student is allowed to use, as appropriate to type.
    2. Care should be taken that the student does not adopt an excessively nose down attitude when practising no-hover take-offs.
    3. No-hover landings can and should be practised from any type of approach.
    4. Point out the similarities of the run-on landing to an engine failure in the hover with regard to groundspeed and pedal control.
    5. When practising cushion take-offs stress the need to have a positive airspeed, approximately 30-40 knots, before adjusting to the climb attitude.
    6. Initially when demonstrating steep approaches use an open area preferably with a line of trees or bushes over which you can shoot the approach and ensure that the student can see the intended landing spot over the trees.
    7. Steep approaches and towering/vertical take-offs lead on naturally to confined areas, therefore take the opportunity to demonstrate a confined area at the end of the lesson.
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