A US Marine who was deployed to Australia on a six-month rotation has used a chopper to propose to his girlfriend who lives in Darwin.

Staff Sergeant Brian Record, who is originally from Florida, flew into East Point with the support of his colleagues last month with a banner and an engagement ring.

Definitely a story to tell the grand kids! (Supplied)

"There was a lot of input and enthusiasm in helping me set it up," he said.

SSgt. Record was able to disguise the proposal as part of the Darwin Military Museum's 50th birthday, and his girlfriend - now fiancée - Melissa Tamblyn, had no idea it was coming.

"When he was on his knee and he started talking, and then I looked at the banner I went 'Oh my god, he's proposing!'" she said.

Melissa had no idea SSgt Record planned to propose. (Supplied)

The happy couple met in Darwin on a night out. (Supplied)

"I was so surprised, and I wasn't expecting it but it was definitely a great thing.

"I'm so happy that he organised it and did such a big grand gesture and everyone could help and support Brian in doing that."

The pair met on a night out in June in 2016, during SSgt. Record's first return rotation to Australia.

Ms Tamblyn had been having dinner with a friend, when they decided to continue their night out on Mitchell Street.

"I was pretty happy as you are, after a few bottles of wine," she said.

"I was like 'alright, we'll go to Monsoons for one'."

SSgt. Record had been at the same venue with some colleagues from work.

Ms Tamblyn had briefly spoken to SSgt Record, before she started dancing on an elevated platform in the nightclub.

They then started a relationship which progressed into long-distance. (Supplied)

"It looked like she was about to slip, and I moved a little bit closer," he said.

"Then she did slip and fall and I reached out and grabbed her and fortunately so, because I think it might have kept her from getting hurt.

"She decided to give me a little more attention after that."

A few days later, SSgt. Record sent Ms Tamblyn flowers at work to "let her know" he was "thinking of her".

They then started a relationship, which progressed into long-distance when SSgt. Record moved back to Hawaii for work.

It wasn't without criticism.

"In the Territory, it's quite transient with the military and a lot of people coming and going," Ms Tamblyn said.

"Everyone was like 'No, you don't want to be hanging around with him'.

"But once I got to know Brian, and I spent more time with him, I thought well I've got to give this a go, and it's been the best thing that has happened."

Ms Tamblyn has since visited SSgt. Record in Hawaii on multiple occasions, and he has returned to Darwin on two more rotations.

The pair planned to be married in Hawaii within the next 12 months. (9News)

He is due to head back to the United States at the end of the month, and they're now using the last of their time together to begin planning their wedding and future.

"Hawaii is half-way in between both families so that's probably going to be a good point to start with for the wedding," Ms Tamblyn said.

"Eventually we'll work out visas and all that sort of stuff."

"There's a lot to organise, but a nice low-key sort of wedding in Hawaii... I can't really go wrong with that."

"I don't think anyone would be too upset about a destination wedding," SSgt. Record said.