A dog-leg is a deliberate mid-ascent turn: the rocket launches on a safe heading, then bends its trajectory toward the inclination it actually needs. It buys orbits a launch site's geography forbids, at a known cost in payload.
Understanding Dog-Leg
Geography's fingerprints on the catalogue
Look at any launch site's history and its azimuth fan is visible in the inclinations it produced — and dog-legs mark the exceptions. Corridors around populated coastlines, treaty-limited overflight of neighbouring states, and drop zones for stages all bend trajectories in documented ways. The reopened polar corridor from Florida — a southerly dog-leg hugging the coast — is the modern showcase, trading a modest performance tax for polar access without a second launch site.
Dog-legs versus on-orbit plane changes
The alternative to steering during ascent is fixing the plane afterwards, but LEO plane changes are ruinously expensive (full orbital velocity times the sine of the angle), so ascent steering almost always wins for meaningful angles. The genuine competitor is patience: nodal precession drifts planes over weeks, and some missions launch into a reachable plane and let Earth's oblateness rotate them to the target — celestial mechanics as the cheapest dog-leg of all.