> If one engine starts even a fraction of a second too late, it will suck up the exhaust from the other engines with predictably mission ending consequences. I

> If one engine starts even a fraction of a second too late, it will suck up the exhaust from the other engines with predictably mission ending consequences. It's even more precise than that. The engines will be started in pairs, a few dozen ms apart, in order to minimize the risk of sympathetic vibrations tearing the rocket apart.