Precautionary Landing

Precautionary Landing

Objectives

  • The procedures to be followed in preparation for a landing at an aerodrome where the surface condition is unknown, an unfamiliar aerodrome or landing area, or an unprepared surface.

Why?

  • you may need to execute a precationary landing to handle emergency situations.

Link

Review questions

  • How coud you determine wind direction?
  • How do you judge if you are low on the approach, how do you correct it?
  • During a soft field landing, why should you hold the airplane one to two feet above ground as long as possible?
  • What illusions you should observe when flying at low altitude with strong winds?

Precautionary Landing basic theory.

Causes of Precautionary Landing:
  • Aerodrome surface conditions, unfamiliar aerodrome or landing area.
  • Fuel shortage.
  • Deteriorating weather
  • Lost
  • Approaching darkness
  • Sickness
  • Mechanical problem…
Landing area:
  • Sufficiently long.
  • Smooth and firm.
  • As level as possible.
  • Free for obstacle.
  • Into wind, if possible.
  • Except in emergency situations, pilot are not at liberty to use an area indiscriminately for landings or take-offs.
Wind direction and speed
  • Try to land with headwind.
  • The drift of your airplane is the most important indication of wind direction and velocity.
  • Smoke or dust gives a good indication of wind velocity.
  • Tall grass and crops ripple give a good indication of the wind direction.
Detecting obstacle:
  • Wires and tower are difficult to see especially in condition of poor visibility.
  • Many obstacles appear camouflaged against ground terrain.
  • Power or telephone lines parallel to many roadways.
  • Trees frequently border fields.
  • Laneways …
  • Be careful many hazardous obstacles look different from the air than they do from the ground.
Speed:
  • Low speed:
    • More time to inspect the landing area
    • More difficulty to control the airplane (risk of stall especially with turbulence.
  • High speed:
    • Less time to inspect the landing area
    • Less difficulty to control the airplane (risk of stall especially with turbulence.
Altitude:
  • The lower you fly:
    • Closer you are to what you are inspecting.
    • Greater the likehood (probabilite) of getting to close to obstructions.
  • The higher you fly:
    • Ability to see details on surface decrease.
    • Less chance of encountering obstructions.
Inspection of landing surface:
  • If fly directly over the surface you will be unable to see below. You must fly to one side.
  • Fly close enough to see as clearly as possible.
  • Far enough to the side to have a clear view without having to look through wheels, struts, or other parts of the aircraft.
Length of the surface:
  • Rule of thumb:
    • At 60 kt you cover 100 feet each second.
    • Multiply the time in second by 100 and you get approximately the length of the field.

Suitability of the landing surface

You must consider whether the field is smooth, level and hard enough to support the aircraft.
  • Signs of soft field
    • Dark colored field with sigh of having been recently cultivated
    • Standing pools of water, snow-drifts and evidence of deep snow.
    • After significant rain, areas at the base of hills are more likely to be moist and soft than areas at the top.
  • Too much rough:
    • Rocs, holes or furrows in the field.
  • Avoid also:
    • Uneven terrain.
    • light and dark patches.
    • Tall crops.

C.O.W.L.S (check, for suitability in landing)

  • Civilization (nearby).
  • Obstacles.
  • Wind.
  • Length.
  • Surface.

Precautionary Landing: Procedure

  • Emergency situation
    • weather (cloud base and visibility).
    • Lost.
    • fuel remaining…
  • Non-emergency conditions
    • Landing at unfamiliar aerodromes/landing areas.
    • The surface condition is unknown,
    • or both;
  • Determine wind direction and speed and select suitable field, best landing run and overshoot flight path.
  • Once you make your choice:
    • Pick key points (where to turn crosswind, downwind, base and final) to construct you own circuit.
High level step:
  • Slow the aircraft down to the recommended power and flap setting (check POH), carb heat on.
  • Descent to 1000 feet AGL.
  • Enter on upwind side at 1000’ AGL (if possible keep the landing area on your left hand).
  • C.O.W.L.S
Low level step:
  • Slow the aircraft down to the recommended power and flap setting (check POH), carb heat on.
  • Descent to 500 feet AGL.
  • Examine the surface closely.
  • Take a decision about the field.
  • Overshoot.
  • Climb back up to nomal circuit altitude.
Final circuit:
  • In downwind do the 3P check:
  • Pan-Pan call.
  • Pax briefing.
  • Pre-landing check.
  • In most case perform a Soft field landing.
  • Aim to touchdown in the first third of the field.

*Important:

  • When you do not have enough time for a full procedure (low ceiling for instance) or, you are familiar with the airport but unsure of runway condtion (if no service available), you will omit the high level inspection circuit.
  • With partial power, mechanical problems, or when icing has occured, you will omit the low level inspection.

Review questions

  • What do you have to consider when selecting a field for a precautionary landing?
  • What are the three steps of a precautionary landing?
  • What are the 3P’s?
  • What does the acronym cowls mean?
  • In what situation could you omit low level inspection?