by Nathan Hanney (June 2000)

The aim of the circuit or circuit planning is to enable the pilot to place the glider in an appropriate position in relation to the airfield to complete a safe landing.

Because a glider has no form of power it is essential that every approach to the airfield be made at an appropriate height for the conditions of the day. There must never be any question of undershoot (not making it back to the airfield during the approach) as the glider has no means of gaining height or stretching the final glide. In order to avoid this, it is necessary to have a pre-determined method by which the pilot can return the glider to a point where the final turn and approach can be made at a safe height.

(See diagram - still to be added)

The way you fly the circuit will depend on several factors, the size and type of airfield, the type of glider being flown and the wind conditions on any particular day. Do not assume that the wind is in the same direction or the same strength as when you started the flight.

However all circuits are made up of three main components:

• Down wind leg
• Base leg
• Final turn, (culminating in the approach and landing).

The DWL begins at the high key area, this will be up wind of the launch point at approximately 800ft, and a field and a half’s distance away from the airfield. You will now be able to easily see all of the landing area and plan the rest of the circuit. The down wind leg is very important, it is at this stage that you must adjust your circuit away from the field if you find yourself to high or edge in closer if to low. This will enable you to make the final turn at the appropriate height and position to the landing area. The DWL also provides an opportunity to make the final checks before landing (known as the downwind checks)

These include:

• Is the landing area clear of other gliders and vehicles?
• Check the wind sock for strength and direction.
• Are you flying through lift or sink?
• Are your straps tight and secure?
• Have you lowered the wheel if retractable and flaps if you have them?
• Are there any other aircraft in the circuit?
• Check airspeed and at the end of the DWL trim speed for the final turn and approach, approximately 50-60kph depending on the day’s conditions.

Base Leg

The correct time to turn onto base leg will depend on your height and the wind condition of the day. However on a relatively calm day this should be a little down wind of the field (see diagram). It is important to remember that you are now flying cross wind and the glider will be edging away from the field. The base leg provides a second opportunity to make fine adjustments to the circuit to enable you to make the final turn at a safe height and position. It is very important to monitor the airspeed as you near the ground during the base leg. An increase in speed will throw away height but too slow could result in a stall or spin without sufficient height to recover.

Final turn

As you approach the into the wind line you intend to land on, a well-banked turn should be made. However, if before you reach this point you appear to be too low turn in early, if to high extend the base leg. After completing the final turn, check airspeed, look well ahead, adjust the airbrakes as necessary and prepare for a smooth or not landing.

Effect of Wind on Circuit

When downwind, you will have less time to complete your downwind checks and you should be starting your base leg sooner, rather than later. You must not use your apparent ground speed as a reference, as the ground will be quickly passing by downwind, but slowly passing by on final approach into the wind. Use your airspeed indicator. As you loose height during the base leg and final approach, anticipate the wind gradient. The wind speed at circuit height may be easily 20 - 30 knots, but substantially less 10 feet above the ground. Therefore, in order to maintain airspeed you will be lowering the nose of the glider progressively, resulting in a steeper than normal approach - hence a shorter final approach. Make the final turn with extra height in windy conditions. In gusty conditions, be prepared to lower the nose and add extra speed on the final approach.

It is always preferable to go through the far hedge at a few miles per hour, than undershoot the field at speed.