Six passengers and two crew are safe after an emergency landing of a Chathams Pacific small aircraft this morning, when the nose wheel failed to lock and collapsed on landing at Fua'amotu International Airport.

The aircraft was enroute to Ha'apai carrying six passengers, including some foreigners, when the pilots, New Zealanders Nick Caulder and Callum Patterson, got an indication that the nose wheel had not fully extended and locked into place.

Chathams Pacific CEO Craig Emeny, who saw the landing and this afternoon praised the crew, said that they radioed and returned to Tongatapu at around 11:15 am where it was safer to land.

"They were unable to get the emergency system to lock down so we looked at the safest way to land, which is on the hard sealed runway where they could hold the nose off. We didn't want the nose to dig. We had a lot of time to think about it," he said.

Craig said the aircraft landed and eventually they had to put the nose down. "It made a crunchy noise, as any metal does when it's sliding across the runway," he said, but the crew had already stopped the engines.

"The damage was pretty light, two blades scrapped the ground but the engines were not damaged. The nose frame and skin were also damaged.

"My biggest concern is what caused it but that will have to be investigated," he said.

"We do a lot of training and have procedures in place for this kind of thing, and the crew did everything right," he said. "The passengers were praising them too."

The damaged 8-seat Queen Air Aircraft was moved into a hangar at Fua'amotu.

Craig said the small aircraft was servicing the Niuas and 'Eua island, as well as Ha'apai, and the incident means that the service will be suspended for about two weeks until his other aircraft, which is currently being serviced in New Zealand, returns to Tonga. Meanwhile, the Chathams 50-seater Convair 580 will continue serving the Vava'u route.

General manager Noel Gillespie, who is in New Zealand, said in a statement this afternoon that the airline had been directed to look after passengers "after their harrowing experience."