The Auckland City Hospital emergency medicine specialist is also part of the only team of doctors in the country that provides 24/7 care on a chopper, helping thousands every year from potentially fatal injuries.
"It can be really chaotic but my brain likes creating order out of chaos," Harper told the Herald.
"[You're] constantly thinking, constantly adding pieces of the jigsaw and starting to make a picture out of it.
"My brain really likes that sort of stuff. There's a sense of urgency to it."
Harper is a clinical lead among a team of 22 pre-hospital and retrieval medicine (PHRM) doctors. It's a joint venture between Auckland District Health Board and Auckland Rescue Helicopter Trust (ARHT) to add emergency, intensive care, or anaesthesia doctors to the helicopter team.
The service is marking 10 years since its inception and demand is at an all-time high.
The team were called to a record 1187 missions last year and this year it's on track to be another record-breaker.
They have attended more than 800 missions so far this year and more than 1000 missions annually for seven consecutive years.
There are an average of four callouts in a day.
These are around 60 per cent medical callouts, 35 per cent accidents, and the rest are made up of jobs such as rescues or inter-hospital transfers.
Even while the country has been in lockdown, they were called to five jobs in one day.
A system introduced this year, in which a helicopter is automatically dispatched for status-one and status-two patients with certain conditions, is thought to have increased demand.
"We are getting airborne earlier to improve patient response times, especially if there is an early indication that it is a critical or serious incident, but that sometimes means standing down as more information comes through as a result," the ARHT says.
Harper has been part of the team since it began in 2011.
She treats people suffering from medical issues such as a cardiac arrest, stroke or multi-system trauma following an accident, such as a tramper injured in a fall or someone ill at sea.
She recalled saving the life of one young man at Raglan a few years ago.
"We thought he was going to die.
"[We] started his first unit of blood in the back of the ambulance and got him really quickly into the back of the helicopter and flew him to Waikato Hospital and got a second unit of blood in.
"It was just amazing to see his colour change as soon as that blood started going in."
The Auckland team is the only one in the country that can deliver pre-hospital blood transfusions – an important procedure that saves lives.
She said in the six years they have been administering blood transfusions on the helicopter, it has improved trauma outcomes at Auckland City Hospital.
Blood transfusions are part of a string of improvements made to the service in its decade-long history.
Staff now administer clot-busting medication to people suffering a stroke and deliver anaesthesia procedures, all from new, larger aircraft.
"Everything has changed from when we started 10 years ago," said Harper.
"If we've got a critical trauma patient we can actually load them and start the blood [transfusion] en route. I can do an ultra sound, scan of their lungs and abdomen to see if they've got collapsed lungs and if they're bleeding internally, and I can do all that sitting in my seat in the helicopter.
"It's reducing the time we're doing stuff on the ground at the scene and reducing that patient time to definitive care."
Harper said processes are so seamless now that some patients don't even need to stop in the emergency department when they arrive at hospital, but can be taken straight through to a CT scan and on to theatre.
She wants to see the 24/7 service rollout across all of New Zealand, not just in Auckland.
But to be in the business you need to have grit, she said.
Harper splits her time between working at the Auckland City Hospital emergency department, the Auckland Rescue Helicopter Trust - and looking after her two boys, aged 7 and 5.
She admits she doesn't always get it right.
"I don't think anybody does. There are times when work takes priority and times when family takes priority.
"It's really important to be a good role model for [my children] . . . showing them commitment to work and my patients, and also being committed to them as well."
Harper was 19-weeks pregnant with her younger son when the confronting nature of her work really hit home.
She helped treat a family severely injured from a car crash in rural South Auckland.
"There was a young woman who was quite badly injured and . . . I think her children were in the back but she was pregnant as well.
"I just remember thinking: 'God, this could be me', and just thinking, if the worst were to happen, I couldn't imagine, it would have been terrible."
"It was a wee bit close to home."
But Harper's passion for the job is what drives her to work 12-hour shifts, night and day, and to commute all the way from her West Auckland home to the ARHT base in Ardmore.
"It makes me feel satisfied in my work when I can look after someone really sick when we don't know what's going on, and we've worked it out right and the treatment is right and they get better. That's really fulfilling."
Forty per cent of doctors currently working on the helicopter are female - a representation which Harper confirmed was largely down to the work of her and others.
"When I started I was the only woman in the crew. A few months after that another woman started and that was really nice because we were the only women working on the base operationally.
"Simple things like toilet access and things like that were a bit interesting."
She helped organise a network for women working in pre-hospital and retrieval medicine in New Zealand.
What started as a small group meeting in Auckland has expanded to an online network of women working in ground and aeromedical emergency medicine.
Harper also advocates for women to gain leadership positions.
She said the network creates a space for women working in similar fields to understand how they could work on leadership potential and career progression.
"I think a lot of people were finding that was a bit difficult."
She admits that she has never felt limited in her own career as a woman, but recognises she is lucky to be in that position.
"When my mum went to medical school, I think she was one of four or five women in her class of more than 100, so we've got those people to thank for the fact that our careers have not been as difficult."
Although there is a strong female doctor contingent, there are still challenges. There are no female paramedics, air crew officers or pilots working for the Auckland Rescue Helicopter Trust.
Harper also wants to improve diversity within the team, not just gender diversity.
"We're looking after patients, so we need to represent patients who we're looking after."
One thing is for certain here and now. Harper is hugely proud of what her and the team have achieved in 10 years, and Aucklanders are benefiting from that dedication.
"I do it because I love my job. I do it because I'm passionate about caring for our patients," said Harper.
