Briefing: Circuit Planning

Introduction

Aim: You will know how to fly a safe circuit, modified as required for the conditions at the time.

What do we know?

What is a Circuit?

What is its Purpose?

Purpose

“To arrive at the final turn in the right place

at a safe height and speed

with safe alternatives always available.”

The Circuit

The idealised Circuit (does not exist!)

Click to enlarge
Elements of a Circuit
Reference Point

This image is to provide context for the following images in this briefing.
In this example, the Landing Area is the grass next to the runway. The RP is the taxi-way where it joins the runway. The glider is flying in a downwind direction above the airfield – it is NOT on a downwind leg.
  • Where the glider will hit the ground if you don’t round out.
  • Work back from where you want to stop, Ground Run and Float.
Approach Path

  • The Final Approach: a straight line from the Final Turn towards the Landing Area.
  • Aim for two-thirds airbrake throughout.
  • Adjust early.
On approach with RP ahead
Approach Speed

Speed Selection:

  • A target speed, with a stated minimum.
  • A safe margin over the stall and spin.
  • Allow for wind gradient & turbulence.
  • Allow for slope.
  • See also separate briefing on Landings, and Approach Control.
Final Turn

  • Accurately flown: “String, speed, look over the nose.”
  • Well banked is safer than shallow. Approximately 30 degrees of bank.
  • Flown at the Approach Speed.
  • Complete it at a safe height (typically above at least 300′ QFE).
  • Placed to allow two-thirds airbrake approach.
  • Allow for
    • glider performance
    • effectiveness of the airbrakes
    • wind strength.
Base Leg

  • Usually at right angles to the Approach
  • Position it to avoid long approaches
  • Adjust if necessary, using straight section(s)
  • Flying ‘wings level’ allows you to judge the wind strength and direction:
    • Aim for a heading on each leg,
    • note if you need to crab to mitigate drift.
  • If using airbrakes to manage height, aim to hold them steady through the Final Turn
Base Leg
Diagonal Leg

  • Cuts the corner off a square circuit
  • Turn approximately 45 degrees off the Downwind Leg
  • Turn soon after Low Key
  • Keeps the Landing Area in sight
  • Landing Area remains at roughly the same vertical position in the canopy
  • The Diagonal Leg is flexible, to give you safe options
Diagonal Leg gives you options to turn in, or out.
Downwind Leg

  • Usually parallel to the intended direction of landing, but in the opposite direction
  • Starts at High Key, c. 800′
    • Height is judged by the detail you see on the ground. For example, at this height cows have legs.
  • Allows judgement and adjustment: “Height, Angle, Distance”
    • As you go round the circuit, monitor height, angle and distance: e.g. if the height looks good for this stage, and the angle is correct, then the distance must be right (etc)
  • High(er) ground speed
  • Judge the cross wind effect by flying on a heading
Downwind Leg, parallel to intended Approach

Options, options, options

  • Why might we not fly the idealised circuit?
  • Continually review your height and position (height, angle, distance to the RP)
  • Monitor the vario sound
  • Adjust the Landing Area if necessary
    • More upwind
    • Closer to you, or further away
  • Adjust any of the legs, early, to place the Final Turn at a safe height and position
Lookout

Ahead, inside the circuit, outside the circuit

Landing Area

Listen to the radio

Pre-landing

Decision to land: make it a commitment

Wind direction, and strength: windsock

Configure the glider (and yourself) for landing e.g.

  • Dump water
  • Lower undercarriage
  • Secure loose items
  • Tighten straps
  • Set flaps
  • Trim for Approach Speed
  • Look at and move left hand to Airbrake lever

Radio:

  • Listen
  • Make your radio call in good time
  • Offer meaningful information, succinctly
  • Aviate, Navigate, Communicate

Joining the circuit (collision avoidance and lookout): convince yourself no-one else is in, or about to join, the circuit.

Wind Effects
Wind Strength

Affects the position of the Final Turn

Crosswind

Start your circuit on the downwind side of the Landing Area if possible, to improve visibility, as a result of correcting for drift:

Wind Gradient

Add speed for the Approach if you expect a wind gradient, to avoid a stall:

Other considerations
  • Flaps
    • Effects vary
    • Read the Flight Manual
Recap

What is a circuit?

What is its purpose?

How do we join a circuit?

What do we do before joining?

What is our focus during a circuit?

How do we judge our position throughout a circuit?

What can we do if we get out of position?

TEM

Stressful situation – develop your judgement

High traffic density: risk of Collision – lookout, and organised traffic flow

Getting low – develop your judgement, and modify your circuit (landing area) as required