Assessing the launch

Experienced pilots don’t rush to unpack on a launch: they stand and look first, reading the slope, the wind, the sky and the traffic.

That habit starts on your first day on the training hill. Launch accidents keep the same causes — knots, uncontrolled runs that weren’t stopped, obstacles on cramped launches¹ — and many of them can be prevented before anyone inflates.

Start with a briefing

Never fly a site that is new to you without a site briefing from your instructor, the local club or knowledgeable local pilots². Then plan the flight: where you will fly, where the wind makes it unsafe to go, and what to keep clear of³.

The slope and the run

A good training launch lets you reach flying speed while you are still running on smooth ground, then falls away so you clear the terrain. SafePro asks that of second-stage launches and rules out cliff launches⁴. Too gentle, and you need a long run; too steep, and a stumble or a collapse during the run has nowhere kind to go. Steep launches and nil wind were accident hotspots in German data¹.

Walk the run before you lay out. Look for holes, stones, tussocks and long grass: many launch injuries are stumbles, slips and twisted ankles¹. Then look past the point where you expect to lift off. If you abort, where will you stop?

Obstacles and your first seconds

Collisions with obstacles on cramped launches are a regular cause of launch accidents¹. USHPA’s P1 limits recommend no obstructions within 60° either side of the flight path, and a launch from which you can fly straight to the landing field (LZ) without manoeuvring⁶. Its P2 limits also call for visual contact with the LZ¹¹. So look along your launch direction: if the wing pulls you sideways as you lift off, what would you hit?

Look hard for power lines and wires between the launch and the landing field. Contact is likely to be fatal, so the only plan is to stay well clear; USHPA’s P2 ground school teaches students to assume every road has power lines¹².

Figure: A training launch, wind from the top: trees inside the 60° cone, rocks beyond the stop line, a power line along the road, and the lee behind the crest. Not to scale.

Wind: strength, direction and crosswind

Measure rather than guess: many instructors have students use a hand-held wind meter, because the feel of the wind on your face is unreliable¹³. Read the windsock, streamers, trees and water too (reading the wind). The wing, a few metres up, can meet wind up to about 10 km/h6 mph stronger than you feel, many schools warn¹⁴. And watch the gusts, not just the average: USHPA’s P2 limits cap peak gusts and how fast they build⁸.

Crosswind on a hillside is worse than it looks. One school warns that every spine and gully can throw off rotor, and that an angled wind collects turbulence over a longer stretch of slope; it treats more than about 45° as risky, while USHPA’s P2 limit is 25°¹⁵. Student limits are much tighter (see the table above), and your instructor’s limit comes first.

Thermal cycles and dust devils

On a sunny day the launch wind comes in cycles as thermals pass, so judging them is part of the standard assessment¹⁶. After a thermal has gone, the ground needs time to reheat before the next one¹⁷, so watch several cycles before you decide; see thermal cycles on launch. A strong cycle can make the inflation rough, and the lull after it can leave almost no wind.

Thermals build towards the middle of the day, and that is when dust devils are most often seen¹⁸. A dust devil crossing the slope is a reason to wait: they killed three German pilots in 2018–2022, one of them ground handling, and caused a Swiss launch accident in 2025¹⁹.

Where rotor comes from

Air tumbles downwind of anything that blocks it: trees, buildings, rocks, spurs and whole hills. The stronger the wind and the bigger or rougher the obstacle, the worse the turbulence²⁰. Sources disagree on how far it reaches, from about 10 to 20 obstacle heights downwind to more in strong wind²¹. So look upwind of the launch, not just at it. An upwind ridge can also leave a launch in a wind shadow²²; see rotor and the lee side.

The DHV lists typical signs of lee at launch: wind that changes noticeably in strength and direction; calm at launch although it is visibly windy elsewhere; thermals in the air but no cycles reaching launch; very uneven rushing in the trees; other pilots sinking near the slope but climbing further out; and thermal cycles from the front alternating with gusts from behind²³. USHPA teaches students to compare the big picture — cloud drift, water and smoke — with the indicators on launch²⁴.

Traffic and people

Many launches have room for only one wing at a time. Before you go, check that the airspace in front of launch is clear, including any pilot about to top-land or climbing up from below, and that the launch area is clear of spectators²⁵. A quick look around belongs before every inflation²⁶.

Your way out

Decide your abort plan before you lay out. APPI students choose a stop line while preparing: if the wing isn’t right when they reach it, they stop²⁷. Put yours where you can still stop on your feet, before the slope steepens or an obstacle appears. Abort whenever the wing isn’t right; after lift-off there is no more aborting²⁸.

Know where you can land, too: a landing field that is large and easy to reach with height to spare⁴. Ask where you would go if you couldn’t reach it.

Thin air: high and hot launches

High, hot air is thinner: it has a higher density altitude. Your wing flies at its usual indicated airspeed but moves faster through the air and over the ground — about 2% faster for every 300 m985 ft of altitude, so roughly 13% faster at a launch 2,000 m6,550 ft up. Expect a faster, longer launch run and a faster landing. At any one site, temperature makes the biggest difference from day to day²⁹.

Making the call

The card below lists it all.

Common mistakes