I'd imagine, for optimal timing, that it's choreographed to go green at the time the driver should begin going for the pedal. There'll presumably be some reaction time and engine latency that's accounted for in the dance.

As I understand things, the driver is meant to hold the brakes (red light) to aid in tire changing and when the green signal is given, the driver is still liable to wait for the front jack to drop the car.

In regards to reaction time, an NHRA drag racing pro tree perfect reaction time is 0.400 seconds. (Edit: this was poorly phrased; a perfect reported RT is still 0.000, but it’s 400ms from the amber lights.)

I suspect the F1 teams have figured how to shave fractions of a second of reaction time by pipelining the release signal and the final crew members clearing.

For drag racing the green light goes on 0.4 seconds after the last orange light, so you need to react in 0.4 seconds to leave at the green light (in practice you need to react much earlier to account for the time it takes the car to leave). That time doesn't actually reflect their actual reaction time though, humans have a much faster reaction time than that.

Mildly related F1 fact: the green light at the start line comes on a random amount of time after the final red light comes on. This interval can be between 1 and 9 seconds.

Interestingly, the actual release signal to start an F1 race is the red lights going out, not the green lights coming on.

The green lights release the cars to the pre-race formation lap.

There haven't been green lights at the start for many years now. The start signal is the red lights going out.

But you're right about the randomization (although I don't think 9 seconds is right, I've never seen it take nearly as long as that)

This is sort of normal for any FIA standing start. Green light comes on at a pre start chosen, fixed interval between 0.2 to 3 seconds after last red light goes.

F1 has its own dedicated specific rules not seen in any other circuit racing.

Rolling start involves green light coming on at about 50m from the start / finish line and if stays red, start is aborted.

On a pro tree, the three amber lights all come on together with a 0.4 second delay to green. On a sportsman tree, they come on in sequence 0.5 seconds apart and the green is 0.5 seconds from the last amber light on a sportsman tree.

This is triggered by sensors on wheel guns and the front jack. From the driver's perspective, this could even be sooner, as it'll take a while (~200ms) to react to the green light.

The guy in the video spends several minutes talking about how two of the members of the pit crew are responsible for changing the signal to green.

AFAIK the regs state that the signal for 'green' needs to have a human input, the wheel guns now mostly (video is from 2017) have torque sensors which inform a 'green' state when the human lets go of their switch.

Each team does things differently, but the front teams have a CAN network for pit equipment states to be shared for some form of automation.

(I currently work in F1)

Is there a way I can contact you? I am writing a short article on human factors and last weekend's lap 7 safety car restart.

Of course, happy to chat. If you put my username in front of @signal.bio, you can email me

Ha, your nickname and a bit of googling gives away what you do in F1. Fascinating to bump into someone of your position on HN...

I remember seeing an online photo of your work car parked in a street, and someone said you actually drive that car in your civilian life, is that true?

Ha that would be hilarious, but is unfortunately not true :)

There is a very good replica of the previous gen car in the Netherlands. I wouldn't enjoy driving it daily due to the noise https://www.youtube.com/watch?v=WVlgw90Ns7c&ab_channel=19Boz...

Just another big F1 fan (I've watched every race since Mansell won the world championship).

Thank you for helping keep the sport safe, both with Sensor Biometric and the medical car driving. I remember Martin Brundle doing a great piece on the medical car.

I was vaguely aware of the biometric glove tech but looks super cool now I'm reading more about it.

If I understand correctly they are both right, it's a consensus system, i.e. the light will turn green once all inputs are GO