First thermals

Recognise a thermal by feel, by sound and by what the wing does, fly actively through it, and know when you may turn, which way to circle with others, and when to leave and land.

In this lesson you will

Sooner or later the air takes hold of you: a push in the seat, the vario starts to sing, one wing rises. Your first climb in a thermal is a milestone. It is also a step into rougher air: in Swiss accident reviews, most in-flight incidents have happened while thermalling or soaring, year after year¹.

So thermals come into your training gradually, and your instructor decides when. This lesson covers what lift feels like, what to do with it at each stage, and when to leave. Thermals explains where they come from.

What lift feels like

The first sign is often stronger sink: every thermal is surrounded by sinking air, and stronger sink just before a climb often means a thermal is near². Then, as you fly in:

you feel pushed up into the seat, as if it were rising under you;
the wing drops back a little over your head as it meets the rising air, and the brake pressure firms up³;
the vario beeps faster and higher;
often, one wing lifts first.

One wing lifts because thermals are lopsided, with a core rising faster than the edges⁴, so one side of your wing meets the stronger air first: the side that lifts is usually the side the stronger lift is on. Many instructors add that, left alone, the wing tends to turn away from the lift, which is why wings can seem to bounce off thermals.

Figure: From behind: rising air under your right wing lifts it. Notice the cues, then compare the variants, flying straight through and, once cleared, turning towards the lift. The inset shows your path from above.

From behind: rising air under your right wing lifts it. Notice the cues, then compare the variants, flying straight through and, once cleared, turning towards the lift. The inset shows your path from above.

Fly actively through it

Flying through lift

Keep a light, even pressure on both brakes.
Cue You feel each side of the wing through your hands.
Why Pressure changes warn you before the wing moves⁵³.
As the wing drops back on entry, let your hands up a little.
Cue Pushed into the seat, brake pressure rising, the wing slightly behind you.
Why The wing needs its speed; holding it back invites trouble³.
If one side goes soft, brake that side promptly, and let up as the pressure returns.
Cue One brake suddenly light, that part of the wing less firm.
Why Small, timely inputs keep the wing overhead; over-reacting makes it worse⁵.
Hold your heading with weight shift and a touch of brake.
Cue Your landmark stays ahead even when one wing lifts.
Why Unless your instructor has cleared you to turn, straight through is the plan⁶.
As you leave the lift, expect sink and a surge.
Cue The seat goes light, the wing pitches forward, the vario drops.
Why A brief, smooth brake stops the surge³; then hands up to cross the sink.

May I turn in it?

Not until your instructor says so. SafePro warns first-stage students that working any lift so close to the ground is especially dangerous, and tells second-stage students to avoid lift or fly straight through it to calmer air and land normally⁶. USHPA’s recommended P2 limits keep new pilots out of thermals with peak climbs above 1 m/s200 ft/min⁷.

When you are cleared, it is for a day and a place your instructor chooses: gentle lift, plenty of height, well away from the hill and from other wings.

Standards differ When thermalling enters your training

Common ground: Early students fly straight through lift; thermalling comes later, with an instructor, in gentle conditions⁶.

USHPA (USA): Rated P2 pilots may fly in gentle thermals within the limit above; P3 raises it to 2.5 m/s500 ft/min peak climb⁸.
BHPA (UK): Club Pilot training includes pre-soaring and soaring phases, flying with others⁹. No numeric thermal limit is published⁸.
APPI (international): Thermal flying starts at APPI Pilot level, with attention to bank angle and outside collapses. The Thermalling certification needs at least 10 flights in thermal conditions⁶¹⁰.
FAI/CIVL SafePro (international reference): Students soar only under an instructor’s control. Stage 4 needs at least 15 h of flying, some of it thermal soaring¹¹¹².

Summarised from each body’s published material, which changes over time. Check the current official documents and follow your school.

Turning in a thermal: centring

Once you are cleared, thermalling starts with a few simple habits:

Look first. Check the space you will turn into, above and below as well¹³.
Turn towards the side that lifted, if the space there is clear and the turn doesn’t take you towards the hill or another wing. Many instructors teach this rule, because that is usually where the rising air is.
Keep your speed. Never start a turn from minimum speed with deep brake, because the inside wing can stall and spin. Turning in lift needs enough airspeed, and too much outside brake spoils the turn¹⁴.
Keep the bank moderate. USHPA limits P2 (Novice) pilots to 30° of bank, and the BHPA calls 30° more than enough for normal flying, thermalling included¹⁵.
Centre gently. Many instructors teach a simple method: when the climb strengthens, flatten the turn for a moment to move towards the stronger part, then turn again. Your instructor’s method takes precedence.
Watch the turn. A sustained circle can steepen into a spiral dive; if it tightens or speeds up, ease out smoothly and gradually¹⁶¹⁵.

Each circle drifts with the wind¹⁷, so check where the landing field is every turn or two.

Join a thermal circling the same way as the pilot already in it: the first pilot sets the direction¹⁸. Who has priority inside a thermal is worded differently by each system (see the block below), so ask which convention your site follows. Whatever the wording, join in the established direction, keep every other wing in sight, allow for their sudden climbs and sinks, and leave if it gets busy¹⁸¹⁹.

Standards differ Circling direction and priority in a thermal

Common ground: The first pilot sets the circling direction, and everyone who joins circles the same way¹⁸.

USHPA (USA): USHPA’s own rules are not public. US site rules say circle the way the first pilot does, and the lower aircraft has right of way¹⁸²⁰.
BHPA (UK): No public BHPA document states a thermal rule. Circle the way the first pilot does, as the other systems teach, and ask your school about priority; Club Pilots must be familiar with flying in company when thermalling¹⁸.
APPI (international): Turn in the same direction as the first pilot; the lowest pilot has priority²¹.
FAI/CIVL SafePro (international reference): Thermal-soaring priorities are part of the Stage 4 knowledge syllabus²².

Summarised from each body’s published material, which changes over time. Check the current official documents and follow your school.

Europe’s EHPU summary also asks pilots to keep clear of wings already circling in a thermal²⁰.

Sink after lift

Every thermal has a ring of sinking air around it⁴. Leaving lift, expect sink: hands up to get through it, and head for your landing field rather than searching low (In sink and in lift).

Thermic air near the ground affects your landing too. Rising air over dry ground can balloon you past your spot, sinking air over woods or water can put you down short²³, and strong sink just before a thermal releases is among the causes of Swiss landing accidents¹. On thermic days, plan your approach with margin.

Leave early, land in time

Leaving well is part of thermalling: choose your exit direction, know when to give up, and leave a thermal that is drifting you away from the landing field²⁴. Keep the field inside your glide cone (Airmanship).

Leave well below cloud base. Lift often strengthens near the base, and pilots have been drawn into cloud²⁵. Don’t get close in the first place, and if you are being drawn up, descend and move away early²⁶. You must stay out of cloud by law²⁷; Cloud suck has the details.

Land when the day outgrows you: climbs stronger than your limit, cumulus growing tall, a rising wind. Thermals strengthen towards the middle of the day²⁸, and a doubt is a no²⁹.

Common mistake Slowing down to turn tighter

Symptom: Heavy brakes, quiet wind noise, the inside wingtip going soft in the turn.
Cause: Deep brake to stay in a small core.
Fix: Turn with speed, weight shift and moderate brake, and widen the circle instead¹⁴.

Common mistake Circling against the others

Symptom: Another wing comes straight at you round the circle.
Cause: Joining a thermal without checking which way the others turn.
Fix: Watch before you join, and circle the same way as the first pilot¹⁸.

Common mistake Riding the climb too long

Symptom: The landing field is far upwind, and the cloud above you is darker and closer.
Cause: The climb felt too good to leave.
Fix: Set your exit before you start (a ceiling well below cloud base, a drift limit) and leave on time²⁴.

Instructor's note Thermals and SIV

Once you fly in thermals, you will meet bigger collapses sooner or later. Federations recommend a safety course over water (SIV) at this stage; the BHPA calls it the only safe and reliable way to learn the recovery techniques³⁰. Until you have done one, keep your thermalling gentle, high and well away from terrain³¹.

Questions students ask

My vario beeps, but I’m hardly climbing. Why?

The vario shows your own climb, the rising air minus your wing’s sink. A school wing sinks about 1 m/s200 ft/min at best, and more when circling³², so air rising at 1 m/s200 ft/min holds you level at most.

I lost the thermal. Should I search for it?

Briefly, if you have height and room. Low, near the hill or drifting away from the field, fly on and land.

How high may I climb?

Your instructor sets a ceiling well below cloud base. The legal distance from cloud depends on the airspace (see Airspace and the law).

Key points

Lift often follows stronger sink. You feel a push in the seat, the wing drops back, the vario beeps, and often one wing lifts, usually on the side of the stronger lift.
Fly actively: hands up a little as the wing drops back, a brief brake as it surges forward on the way out.
As a student, fly straight through lift unless your instructor clears you to turn. USHPA’s P2 limit is 1 m/s200 ft/min peak climb.
When cleared, look, then turn towards the lift (never towards the hill) with speed and a moderate bank, never from deep brake.
Circle the same way as the first pilot, keep your lookout, and leave if it gets busy.
Leave early: before you drift out of reach, well below cloud base, and before the day outgrows you.

Ground to Solo is a study aid. Paragliding is learned in person with a qualified instructor at a recognised school; nothing here certifies you to fly.