Hawk-Eye Apologises After Error – How Exactly Does Goal-line Technology Work?

After 100 days without Premier League action, its return was marred by an error with the Hawk-Eye goal-line technology system.

Hawk-Eye Innovations, the operator of the Premier League’s goal-line technology system, has apologised after an error denied Sheffield United a goal in their 0-0 draw at Villa Park.

In the 42nd minuted, Orjan Nyland appeared to carry Oliver Norwood’s free-kick over the line. Sheffield United players all believed the ball had crossed the line. However, referee Michael Oliver was unmoved as he did not receive a signal to indicate a goal.

On further inspection of replays it shows that the ball had clearly crossed the line. Blades’ boss Chris Wilder later said “I think the goalkeeper was in the Holte End when he caught it” in an interview where he showed his frustration.

In a statement, Hawk-Eye said it “unreservedly apologises to the Premier League, Sheffield United, and everyone affected” and acknowledged that the ball had gone over the line.

Hawkeye’s latest blunder during Aston Villa vs Sheffield United

Hawk-Eye’s Explanation

Hawk-Eye explained that all seven of its cameras located in the stands around the goal area were “significantly occluded” by the goalkeeper, defender, and goalpost. The company added it was the first time such an error had occurred in more than 9,000 matches using the specialised system.

Wilder added “Seven cameras haven’t picked it up – the most technical league in the world – everything we see at every angle and it hasn’t seen a goal.” Further adding that Hawk-Eye’s statement was “unprecedented” and “unbelievable”.

Hawk-Eye further explained that the system had been tested and was working prior to the match as confirmed by the Match Officials on their pre-match check.

The professional body responsible for Premier League referees – the Professional Game Match Officials Limited (PGMOL) – confirmed VAR was ‘able to check goal situations’. It did not intervene in this situation as ‘on-field match officials did not receive a signal.’ Paul Tierney, the match  VAR, did not check anything and nothing was flagged by the assistant referee to referee Michael Oliver. This suggests that he didn’t have a clear view of the incident.

So how does Hawk-Eye’s goal-line technology work?

Hawk-Eye installs 7 cameras around the goal area. Their website says the most common location is on the roof of the stadium but there is a great deal of flexibility in camera location. These cameras are designed to be high-speed ball tracking cameras, with the images from the cameras processed to find the ball in the image.

The cameras track the ball using triangulation, this requires 2 of the 7 cameras to be able to see the ball. Hawk-Eye state the system is mm accurate.

Once the cameras start tracking the ball, the software combines the information and tracks the ball in relation to the goal. As soon as the system detects the ball has crossed the goal line, it instantaneously sends a signal to all match officials via their earpiece and watch.

We then see the definitive ‘goal/no goal’ 3D graphic replay displayed by broadcasters showing where the ball is in relation to the goal line.

What are the consequences?

In this instance there was no ‘goal’ graphic produced in relation to the goal-line incident.

This is because the system requires 2 or more cameras to be able to see the ball to start tracking it. In this instance, Hawk-Eye stated that all 7 cameras were occluded and therefore were not able to triangulate the position of the ball. It has to be noted this is the first goal-line technology error since its induction in 2013, not a bad error rate it must be said. Although the consequences of this error may be costly for either teams.

This is an unlikely event in the most unusual of situations, which is almost fitting.

This result leaves the Blades in sixth in the Premier League, whilst Aston Villa are still struggling in 19th.

We hope you enjoyed this article about ‘Hawk-Eye goal-line technology errors.’ What do you make of VAR and goal line technology? Let us know!

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