Nowra's Hayley Dun, an Aviation Firefighter and NSW Fire and Rescue Service member stunned her naysayers recently when she became the first person to carry a line of 70mm hose during the Melbourne Firefighter Stair Climb.

The annual event raises money for the Black Dog Institute and Lifeline, helping the emergency service and defence members suffering from PTSD and depression.

The hose, and extra gear combined, weighed in at more than the 27-year-old's own body weight.

With the climb held in September, each climber was assigned one of the 343 fallen firefighter's of 9/11 onto their race cards to climb in memory of.

Hayley dedicated her climb to Kenneth B Kumpel from ladder co 25, who she said is believed to still be amongst the missing.

"Many close to me would know that I have the utmost respect for all firefighters that paid the ultimate sacrifice on that day and doing this climb this year I wanted to climb in memory of them in the same way those men did on that terrible day," Hayley said.

"This year I thought 'I'm going to do it right and carry the hose the same way as those men who paid the extra sacrifice."

"The extra weight is also symbolic of the weight the emergency services personnel suffering with PTSD or depression carry."

The stair climb includes 28 flights, and firefighters must complete it with a breathing apparatus on.

As she donned her equipment, Hayley said the comments started to flow.

"When people saw me with the hose line, they were all doubtful, not in a mean way, but everyone knew it was going to be a challenge and I was getting so many negative comments that I started to doubt myself," Hayley said.

Hayley said those doubts kicked in hard and fast at the second flight of stairs, but slowing her breathing and keeping her thoughts calm and strong kept her going.

She described reaching the top as "amazing" - along with the feeling of proving the doubters wrong.

"I even had a guy come up to me later on that day and he said 'I have to be honest, there was a group of us saying 'look here's firefighter barbie - what floor do you reckon she'll give up or drop the hose?'," Hayley said.

"I was pretty stoked when this same guy said 'but you just proved everyone wrong!".

Hayley's already planning on taking on the climb for the third time in 2020.

She's brainstorming ways to inspire more people to partake in memorial climbs and challenge themselves - but not before enjoying a well-deserved massage.

Donations are still open on the Melbourne Firefighter Stair Climb website.

If you or someone you know is in need of crisis support, phone Lifeline on 13 11 14.