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P2 Course - Module 6 – Ridges, Rules, and Thermal Flying

Ridge Soaring

One of the simplest ways to enjoy long flights is ridge soaring using orographic lift. Orographic lift is generated when a continual wind is compressed as it moves up over an obstacle such as a ridge, hill, or mountain. Flying in these areas of lift – called lift bands – can be very smooth.

However, there are a few dangers to be aware of. Most importantly you must always turn away from the hill.Ridge soaring generally takes place close to the terrain, so if you fly downwind, you are very likely to fly into the hill before you can make a 360° turn. This is why, when flying close to the terrain, we always make figure-8 turns away from the hill.

To maintain or gain altitude you must stay in the lift band that extends outward and upward from the terrain. It is advisable to stay as far out in front of the hill as possible while remaining in the lift band. If you are close to the hill, deep in the lift band and the wind increases, you may get stuck there or blown over the back. To avoid this situation follow the rule ‘if you’re going up, go out’.

If, while remaining a certain distance out in front of the hill, you find yourself suddenly going up, the wind is increasing or the direction has become straighter. Move further out front until you are in a better position and less likely to be blown over the back. If the wind decreases you can retreat back to the hill where the lift will be stronger. Your speed-system is the best option for positioning yourself on the front edge of the lift band.

Be aware of the fast and slow beat while ridge flying. When flying up and down the ridge line, you may find that you are covering ground quickly in one direction, and slowly in the other. This happens when the wind is not perpendicular to the ridge. You have a partial tailwind going one direction, and a partial headwind in the other direction. If you choose to perform a top or side-hill landing while ridge flying, it would be wise to land on the slow beat, or in the direction you are moving the slowest.

Keep in mind, that in relation to the ground, your glider will seem to respond faster when turning on the slow beat. Conversely, when turning on the fast beat your glider will seem to turn slower and respond sluggishly. It’s not actually turning any differently, but you are covering different distances depending on whether or not you have a headwind or a tailwind. When turning during the downwind beat, it is wise to begin your turn earlier than you would expect.

When a wind passes through a constricted area, it becomes compressed and speeds up, creating a Venturi effect. When wind passes over a terrain feature, it produces ridge lift. When it passes through gaps or between features, we get higher winds without the lift. This is a problem to consider when crossing a gap in a ridge because there is little or no lift, and higher wind speeds. Make sure you have extra altitude and terrain clearance to avoid being trapped in these areas of high winds. Don’t confuse gaps with depressions or bowls. The wind will be stronger in the bowls, but so will the lift, because the terrain is still deflecting air upwards.

If you are ridge soaring a rounded hill be aware of the ‘seam’. This is the best area of lift and will be a narrow window perpendicular to the wind flow. When flying this area of lift, you will notice that you have a fast and slow beat on both sides of the seam. When you fly out of the seam, you’ll notice an increase in your ground speed. This is your cue to turn back into the seam and onto the slow beat. If you fly too far on the fast beat, you may find yourself unable to penetrate back upwind or in rotor behind the hill.

When launching on a round hill, it is important to identify the seam and launch directly into it. It will help if you pick a horizon reference point, so you can recognize if you are getting pushed off your launch heading which is very common in this scenario.

Rules of the Ridge

When ridge soaring with other pilots, space can be limited. There are rules governing the traffic pattern that will help keep you and other pilots safe.

Pilots approaching head-on should both yield to their right. This keeps pilots from having to guess which direction the other is going to turn.

The pilot with the ridge on their right has the right of way. Usually the pilot with the ridge on their right is also closer to the hill and has no room to allow another pilot to pass between them and the hill. Therefore, the pilot with the hill on their left is responsible for making space and moving further away from the hill.

Lower pilots also have the right of way. If you are over another pilot they won’t be able to see you through their canopy. If the lift increases, they could rise into you unexpectedly.

If passing another pilot from behind, pass between the pilot and the hill. You do not want to trap another pilot against the hill leaving them nowhere to turn. If you want to pass, you need to put yourself in the danger zone.

If two pilots are at the same altitude heading in the same direction, the pilot on the right has the right of way. This can occur during a landing approach. When following another pilot into a turn you may either follow directly behind them, or make your turn at the same time, putting yourself in the lead for the next pass. Most ridge sites will have a pattern, following the basic ridge rules, that you will begin to recognize after watching for a while. Remember, if in doubt, ask a local.

Thermal Flying with Traffic (Gaggle Flying)

Flying with other pilots can greatly enhance your ability to map out a thermal and stay in the air longer. When you find yourself flying with a group, it is usually referred to as “gaggle flying.”  Thermal flying will take some time to figure out, but if you find yourself in a thermal with other pilots, there are a few rules you need to know about.

The first pilot in a thermal establishes the direction of the turn. If you find the thermal first and you like right turns, by all means turn right.

All pilots must turn the same direction. If somebody else is already in the thermal and turning left, you need to turn left as well. Again, lower pilots have the right of way. The pilot below has limited visibility above them and may not be able to see you. Even if you were the first person in the thermal, and they enter it turning the opposite direction, you will need to change direction to match theirs. As in ridge-soaring, the pilot below will encounter lift first so you should avoid flying directly over anyone.

When joining another pilot at the same altitude in a thermal, enter tangentially (opposite) to their circle. Don’t cut through their flight path. By entering tangentially – or opposite them – you can smoothly join the other pilot without disrupting their turn.

You may join a thermal between two sets of pilots who, for whatever reason, are turning opposite directions. You should turn the same direction as the closest group, keeping in mind that the group below you can’t see up. Keep track of the pilots at your level. If you are in a “gaggle” of pilots you won’t be able to keep track of everyone, so focus on the nearest pilots. When flying with other aircraft, keep in mind the performance of each and respective visibility restrictions. This will help you decide how to interact with them. Paragliders will be the slowest, followed by flex-wing hang gliders, rigid wings, and sail-planes. Generally the slowest craft can turn the tightest and so will generally be at the center of the circle.

See and Avoid

Any time you are flying the most important rule is to see and avoid other air traffic. Looking in the direction you intend on turning will help you be more aware of your surroundings, and let others know which direction you are going. 

While flying in traffic, it is your duty to be aware of your surroundings.

See And Avoid. It is your responsibility to be mindful of the airspace you are occupying and identifying any potential hazards near you. Another way to express this concept is “keep your head on a swivel.”

You will hear this called ‘situational awareness’. Other pilots will expect you to follow standard traffic rules and as such: You need to take your right of way as expected, but don’t assume all the other pilots are paying attention or know what they are doing. Collisions will always be the greatest danger while flying in traffic, so monitor the surrounding pilots by keeping your head on a swivel’ and always maintain a safe distance.

Right of Way Rules – Review 

  • Pilots approaching head-on should both yield to the right.
  • The lower pilot has the right of way.
  • The pilot with the ridge/mountain on their right has the right of way.
  • Pass other pilots from behind between them and the hill.
  • The first pilot in a thermal sets the direction of turn.
  • All pilots must turn the same direction in a thermal.
  • Enter thermals tangentially to the circles other pilots are already making.
 
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