The Hitech Grand Prix driver took his second series victory on Saturday after taking the lead from Logan Sargeant off the line.
A “stressful” technical issue meant he had no radio link to his engineer throughout the race, forcing him to keep an eye on the TV screens around the circuit as cues instead.
The Kiwi says he was forced to sit in second gear during the VSC as he had “no clue” when the lights would go green, but a well-placed screen as the period ended proved his saving grace.
Armstrong managed to get the jump on a rapid second-placed Jehan Daruvala and went on to take his first victory since Jeddah last year.
He said: “I quite enjoyed it, it was very peaceful. I was alone with my thoughts, so to speak.
“But then again it’s always nice to know the gap behind and what’s happening generally.
“Luckily there’s quite a lot of TVs around the track so I could keep an eye on the TVs when I’m driving, what’s going on.
“I could see that he was never really that close on the TVs so I didn’t stress too much.
“But on the VSC restart, that was quite stressful I must say, because you sort of need your engineer to tell you the virtual safety car is ending, be ready to go, and in this case I had no clue.
“So I was always sitting in second gear ready to go even if the virtual safety car was still going.
“That was stressful, but luckily it went green when there was a TV above, so yeah, quite lucky.”
Armstrong, who is currently fifth in the drivers’ standings, said he “thought he’d be in the lead before the first corner” after spotting a fresh set of Pirellis on polesitter Logan Sargeant.
But he bemoaned his start from second on the grid, which he said was “not as clean as I would have liked.”
“I don’t know why Logan started on completely new tyres for the race because normally we warm them up before doing the start and as soon as I saw him starting on a brand new tyre I thought I’d be in the lead before the first corner,” Armstrong said after the race.
“I didn’t do a very good start but luckily still kept the lead.
“And then the rest of the race, I mean, Jehan was super fast and I expected him to be fast at the end.
“I feel as though I know more or less what he wants to do, we’ve talked about this a lot because we’re quite good mates and I knew he’d try and back off, save his tyres a bit and then attack at the end and apply some pressure.
“So I always kept some margin with my tyres just so I could defend him if he came strong at the end, so I’m happy to finally get a win this season.”
