Lewis Hamilton says he had to try to overtake Nico Rosberg once it became clear his teammate was in a slower engine mode before their Spanish Grand Prix collision.
Hamilton and Rosberg crashed out of the opening lap when the world champion attempted to pass his German teammate on the exit of Turn 3, only to be pushed onto the grass, where he spun into the other Mercedes car. The move had been possible because Rosberg's engine had entered an incorrect mode and was harvesting (or derating) on the exit of Turn 3, meaning he was roughly 160bhp down on power -- around 17km/h.
Explaining the crash from his perspective, Hamilton said: "Basically from me I got a good start, I just got slipstreamed into Turn 1 and then through Turn 3 I was a lot quicker than Nico. Nico just happened to be in the wrong engine mode and he derated, which I didn't, and I was gaining at him at fairly decent pace. Where he positioned the car, I was a car width to the right of the racing line and at the speed I was catching him I had to decide whether to go left, which is a small gap, or right.
"The inside line is always the one you'd go for, there was a much bigger gap and I went for it. I got there and I had part of my wing and part of my wheel alongside within the white line and then that diminished pretty quickly. I did what I could to avoid an incident pretty fast by going on the grass ... But it all happened pretty quickly."
Hamilton first realised Rosberg may have entered an incorrect engine mode when he saw the flashing rear light of the No.6 car as they came through Turn 2 and 3, indicating engine harvesting was taking place.
"It didn't take me by surprise, I could see the derate light, but then it switched off so I wasn't making any assumptions about what was going on. But I had a better run, basically, through the corner. He didn't have the power from then... he did make a switch change afterwards but when you make that change it doesn't kick in for 100 metres or whatever at that speed. So even though he changed it it wouldn't have made any difference."
While Mercedes is currently looking into what caused the incorrect engine mode, Hamilton thinks it must have been down to Rosberg forgetting to hit a button while waiting for the lights to go out.
"We can't be told what to do but before the race we have these procedures you've got to go through. When you stop on the grid there's only one mode you go to, which is the race mode. Nico was in that same mode for the whole formation lap so I assume he forgot to change it when he got to the grid.
"But once you're into launch mode, we're both in the same mode. I think once he got to Turn 3 he disengaged the launch mode, as I did, but I went to race mode and he went to another one."