McCartney started at four metres, which she easily cleared, and then 4.40m, which she was over on her third attempt before the bar was raised to 4.64m. She missed her first two attempts but was well over on her last attempt to qualify for nomination to the Rio Olympic Games.
The world junior championships bronze medallist and world university games silver medallist now holds every New Zealand women's record in the pole vault including breaking the New Zealand all-comers record of 4.57m set by Australian Emma George in 1998. This was the world senior women's record at the time.
She was almost speechless straight after the event.
"I kind of don't know what to say right now," said an overwhelmed McCartney.
"It's an incredible feeling. I don't even know how to explain it but I'm just overjoyed at the moment."
It was her first run-up of 12 steps since the world university games in July.
"So I was still kind of feeling it out with the poles and especially because it was so windy today it changed what poles I was on quite a lot. So it took a little bit of feeling out but we got there in the end."
She had a few anxious moments on getting to the final result.
"I tend to leave them to the third attempt, which I shouldn't do, but it happens sometimes," she said.
A bit of fine tuning took place before going in for the final attempt.
"Jeremy always gives me immediate feedback which is awesome obviously and we just talk over what happened in the last jump and make a decision for what needs to change in the next one whether it is going up poles or changing the uprights."
Coach Jeremy McColl, twice New Zealand pole vault champion, was delighted with his athlete's performance.
"The windy conditions should have affected her but she had her head on today and she jumped great."
After missing the first two attempts at the record height it was quickly back to the drawing board.
"We ended up going on to a bigger pole because on her second attempt she hit it on the way up so we knew we only had one more attempt so we had the option of pushing the up-rights back or going on to the stronger pole.
"She's never used this pole before from 12 steps so we decided to have a crack on the bigger pole and give it a go, but the way she was jumping there was never going to be an issue with the pole it was just a matter of channelling all the energy in the right directions," said McColl.
He added that McCartney was a pleasure to coach.
"All the work has paid off, we're a great team, we get on really well and she does all my programmes and does what she's told. She's actually quite a breeze to coach ..."
Other New Zealand athletes to have set a world junior record have been Valerie Sloper with a shot put of 14.11m in Christchurch in 1955, Mary Donaghy with a high jump 1.68m in Wellington in 1956, Beverley Weigel with a long jump 6.23m in Auckland in 1957, Gavin Lovegrove with a javelin throw 79.58m in Noumea in 1986 and Jacko Gill with a shot put of 23.00m in Auckland in 2013.
