The Mercedes Formula One team has offered further details of the miscalculation that cost Lewis Hamilton victory at the Australian Grand Prix.
Hamilton appeared to be cruising towards an easy win in the opening stages of Sunday's race but was leapfrogged by Sebastian Vettel when the Ferrari driver made his pit stop under Virtual Safety Car (VSC) conditions. Hamilton had stopped several laps earlier under full race conditions and Vettel benefited from making his tyre change while the rest of the cars were running at a reduced speed under the VSC.
Mercedes was aware of the danger Vettel could pose under a VSC period, but according to its calculations Hamilton would be safe if he kept within 15 seconds of the Ferrari. That number proved to be incorrect and when Vettel made his stop he emerged just over 0.6s ahead of the Mercedes and held the lead for the rest of the race.
After looking into the cause of the miscalculation, Mercedes' trackside engineering director Andrew Shovlin gave a more detailed explanation of what went wrong in a Mercedes YouTube video.
"We identified that there was an issue with the software that was telling us at that point that Lewis was safe and that Vettel would drop out behind us, and then obviously you saw what happened and Vettel dropped out in front after he came in for his pit stop," Shovlin said. "The issue isn't actually with the race strategy software that we use, it was an offline tool that we create these delta time laps with and we found a bug in that tool that meant that it gave us the wrong number.
"The number we were calculating was around 15 seconds and in reality the number was slightly short of 13 seconds, so that was what created our delta. We thought we were safe, we thought we had a bit of margin but you saw the result, we dropped out and we were second place and it's very difficult to overtake and we couldn't get through."
Shovlin said the team would change its processes to allow more of a margin for error in the future.
"How we deal with these sorts of problems with the software is the same that if we had a reliability issue and a bit on the car broke. It's really just about understanding everything that went wrong, gathering all the data, and invariably it's never just one thing that went wrong. There are elements that we can do better with calculating that but also when we look at it in the future we are going to make sure we have more margin because we want to be able to cover for Vettel doing an amazingly good in lap or having an incredibly good stop.
"So as with any of these things, we just look at everything that went wrong, work out how to solve it and then put the processes in place to make sure we don't have a repeat."
And Shovlin confirmed Hamilton would had the pace in the car to push harder and keep Vettel behind had the team understood the situation better.
"The simple answer is we could have pushed the car harder. At this point of the race we were still following a fuel profile that meant we were having to do some saving of fuel. Melbourne is a very difficult race to do on that 105kg limit. Also we were being a bit cautious on the tyres because the team though that we were safe anyway, we thought that Sebastian was going to drop in behind us we weren't telling Lewis to push any harder.
"That is one of the big frustrations coming away from Melbourne is that the car was clearly quick enough to win the race and if we'd managed the race differently we could have won it. But at this point we were lulled into this false sense of security and we didn't have Lewis driving as fast as we could. That's one of those areas in the future where we need to make sure we have got more margin and make sure that all of these tools are giving us the right instructions so we can put the car in the place that we need to on track."