The Royal New Zealand Air Force P-3K2 Orion surveillance aircraft flew out within 48 hours of the eruption and was able to capture the first post-disaster photos.
PMN News reports Flight Lieutenant Dave Evans says the crew didn't know what to expect.
“Once we got up there, the thing that really struck me was the colour. Everything was a really strange colour as everything was covered in ash.
“We went up to Mango island and we could see everybody and it looked like they’d gathered at the centre of the island and put some tarpaulins up, so it was obvious that some people survived but there was real concern about ‘what had these people suffered?’.”
They could see people moving around, but couldn’t make out whether they were injured.
“There was a lot of concern on the crew for the people and how they fared. I was gutted to see the state of it. At this time, we didn’t know how many people had been lost.”
Evans says the crew of 12 had to turn their attention to the task at hand.
“It gets really professional. It became evident quickly that there were really major problems with water supply.
“We were really interested in the state of the ports and the airfields, the condition of the runways, the airport facilities and when they’d be able to handle air trafficking again so we could get the transport aircraft with the aid in.
“We were just hoping as a crew when we were flying around, that just seeing us would be an indication to those on the ground that help is on the way."
Evans was also onboard the second reconnaissance flight on the 19 January, and on the way back, flew over navy ships HMNZS Wellington and Aotearoa heading to Tonga.
“We were able to pass them information that we'd been to the port and it looked OK so they should be able to get in. They also had to send in some divers to make sure the sea floor hadn’t shifted too much.”
One year on, Evans says the low number of deaths is baffling.
“I was really surprised to hear how few casualties there were given the absolute destruction that was on the west coast.
“You look at the pictures and you look at the actual casualties and the two just don’t marry up. It’s amazing that so many people survived there.”
In February, some of the ships providing aid were brought back to New Zealand.
Commander Joint Forces New Zealand rear admiral Jim Gilmour says the HMNZ ships Canterbury and Wellington were no longer required after the shift from immediate relief to long-term response.
“The NZDF provided an immediate response to relief efforts and over the past month we have supported Tonga with deliveries of essential supplies, food and water to help meet the basic needs of those who have been affected by this disaster.
“The Kingdom of Tonga has expressed thanks for our help with the initial relief response, and they’re looking now to the longer term recovery ahead.
"As always, the NZDF remains ready to assist if we’re called on again. We have aircraft on standby to take more supplies if required."
Crew onboard the P-3K2 Orion were first to see Tonga after the eruption. Photo/NZDF