Hawk-Eye in Cricket: LBW Accuracy and Ball Tracking
How Hawk-Eye ball tracking works for cricket LBW decisions, its accuracy, limitations, and the umpire's call concept.
Hawk-Eye ball tracking is central to cricket's LBW DRS reviews, predicting where a delivery would have gone after striking a pad. Its accuracy shapes LBW dismissals across all levels of international cricket.
The Technology
Six calibrated cameras capture the ball's trajectory from multiple angles. Hawk-Eye builds a 3D model of the ball's path before impact, then extrapolates its continuation based on physics models of bounce, speed and trajectory.
The Uncertainty Margin
Cricket explicitly acknowledges Hawk-Eye's uncertainty. Balls clipping more than half the stump can overturn LBW decisions, but balls showing as 'umpire's call' (only barely hitting) leave the on-field decision intact.
Criticisms
Critics note the projection model cannot perfectly account for pitch irregularities, seam movement variations, or spin deviations. What appears as precise on screen involves significant modelling assumptions that can produce errors.
Strategic Use
Teams and batters use Hawk-Eye data between sessions to analyse trajectory patterns. Bowlers check where their deliveries are hitting the stumps; batters examine where they are being beaten — analytics complementing DRS usage.
Frequently asked questions
How accurate is Hawk-Eye for cricket LBW decisions?
Hawk-Eye claims approximately 3.6mm accuracy. Cricket acknowledges limitations through 'umpire's call' — if the ball only marginally clips the stump, the original decision stands.
What is umpire's call in cricket DRS?
Umpire's call means Hawk-Eye shows the ball clipping the stump but with insufficient margin to overturn the on-field decision — the original ruling stands.