The geometry does the flying.
At the start of the ground run the cable pulls almost horizontally, and every newton goes into speed. As you rotate and climb, the angle between cable and glider steepens, and the same pull splits: part of it still tows you forward, a growing part pulls you down. Near the top the cable is almost vertical beneath you and can add nothing but load — the climb flattens on its own, and no winch driver and no amount of back stick can change that.
That is why release height is a fraction of the cable run rather than something you fight for: roughly a third of the distance to the winch on a calm day, approaching half in a strong headwind. The wind helps for the same reason a kite climbs on a windy day — with more air passing over the wing for the same ground speed, you climb steeper over the same ground, and the geometry pays you at the top.
The speed window is written on the wing.
On the cable your wing is not lifting one glider — it is lifting the glider plus a large share of the cable tension. The load factor in a steep climb sits around 1.5, and stall speed scales with the square root of load, so a glider that stalls at 65 km/h free-flying stalls near 80 km/h on the wire. That is the entire reason for the classic minimum-speed rule of about 1.3 to 1.5 times the free stall speed: the margin you think you have from the placard is not the margin you have mid-climb.
The top of the window belongs to the machinery: the weak link and the maximum winch-launch speed protect the structure and the release mechanism from each other. Too fast is signalled and the winch driver eases off; too slow is corrected by you, immediately, with the nose — never by waiting to see whether it improves.
Forty seconds, drawn to scale.
Slide the wind up and watch the release height climb toward half the cable run — the wind is worth more than the winch. Then walk the break marker up the profile: below 100 metres the only conversation is land ahead; above 200 you fly something like a circuit; between the two lives the grey zone every site briefs differently. The band heights here are teaching numbers — your site briefing governs.
Rehearse the break, not the launch.
The launch itself is forgiving; the break is a test with a time limit. At the moment the cable goes, the glider is pitched up around 45 degrees with the airspeed already decaying, and the only correct first action is always the same: nose down, firmly, below the horizon, and wait for the speed. Every option you have exists only after that. The classic fatal error is not choosing the wrong field — it is beginning the decision while the attitude is still writing a stall.
Then the ladder, from the tool above: low breaks land ahead on the remaining runway, even if the remaining runway is the far hedge at walking pace. High breaks fly an abbreviated circuit like any other landing. The grey zone in between is the reason winch sites brief their numbers before the first launch of the day — the right answer depends on runway length, wind and what lies beyond the fence, and it must be decided on the ground, not at 150 metres with the speed building.
In your cockpit.
Two instrument honesty notes for the wire. First, at 45 degrees of pitch a static system shows its position error at its worst, so the airspeed you see in mid-climb is the least accurate reading of the whole flight — one more reason the minimum-speed rule carries margin. Second, a flight recorder quietly grades every launch: a season of release heights, plotted against the day's wind, tells you more about your site, your winch driver and your own rotation technique than any single launch ever will.
And a cable break at height is nothing more than a compressed version of a decision glider pilots train for anyway: the outlanding article.
An airspeed indicator trusted at the exact moment the speed window matters most.
Height, speed and the release on one 57 mm instrument that stays readable at 45 degrees of pitch.
Every launch in the logbook — release heights over a season tell you about your site, your winch and your technique.