Briefing: Approach Control

Introduction

Aim: You will learn to judge whether the glider is under or over shooting the Reference Point, and how to manage the steepness of the Approach Path.

What do we know?

  • What is a Reference Point?
  • How do we choose it?
  • Why do we use it?
  • How do we control speed?
  • How do we control descent?
  • When does the Approach Path start?
  • When does the Descent Path start?
RP Recap

  • Choose a Reference Area when at Low Key
  • Finalise the Reference Point early in the Approach
  • RP is then ‘fixed’
Controlling the Approach

Use judgement to decide when you have reached the Descent Path. What’s happening here?

With Airbrakes 2/3 open, this pilot is undershooting the grass landing area

When on the Descent Path, the RP should be held fixed in the canopy.

  • This sequence shows a glider On Descent Path, Speed constant, Airbrake setting constant, RP fixed:
  • RP moving Up the canopy indicates Undershoot
  • RP moving Down the canopy indicates Overshoot

A steady Speed (and Attitude) is important. Why?

  • Allows judgement of the Over and Under shoot by reference to the RP’s movement in the canopy. This is not possible if the attitude is changing.

The prior choice of Approach Speed should cater for wind speed, wind gradient and slope, to avoid stalling and to manage the ground speed.

Control the Speed with Elevator by reference to

  • Attitude
  • ASI

Control the Descent Path with Airbrakes by reference to

  • RP movement up / down
How much Airbrake?

Airbrake’s effect on glide slope:

The effect of a headwind:

Ideally use half to two thirds

  • Effect, not Amount

Why so much?

  • Options!

Impact of a wind gradient:

  • Reduce the amount of airbrake to maintain a safe speed:

Beware the shallowing approach!

When does the Approach end?

  • Commence the round-out at approximately treetop height
  • Abandon the RP at this point, to focus ahead (horizon)

Flaps

  • Effects vary between gliders
  • Read the Flight Manual

Recap

An example Approach with overshoot (video)

  • How and when do we choose the RP?
  • How do we judge under / over shoot?
  • How do we correct any under / over shoot?
  • What speed do we maintain?
TEM

  • Stressful situation
    • Judgement will develop
    • Start the Circuit at a safe height, and modify it as needed
  • Collision with the ground
    • Look well ahead just before the round-out
  • Stall / Spin
    • String Straight, Speed Control
  • Glider characteristics e.g. long, low wings, contamination
    • Know your glider and gain experience is the easiest conditions possible.
  • Weather:
    • Low Sun
    • Misting Canopy
    • Cross-wind
    • Head-wind
    • Wind Gradient