A newly-engaged hot air balloon pilot who got a rope wrapped around his neck while landing after a New Year's Day scenic flight was saved by quick-thinking passengers.

The accident happened just after 9am today about 8km from Methven, Mid Canterbury, home to Adventure Balloons New Zealand.

Chief pilot Graeme Church had been flying a group over paddocks with the Southern Alps behind them on the stunning, clear day.

Local farmers spoken to by the Herald told of seeing the colourful balloon passing over without incident.

It was only later when they saw ambulances – and then a helicopter – that they realised anything had gone wrong.

The balloon remains in a farmer's field this afternoon. Photo / Kurt Bayer

The incident, which a company spokesman called a "freak accident", happened as they were ending their flight.

The Transport Accident Investigation Commission (TAIC), which is now appealing for witnesses, said the circumstances reported to them were that Church was "ejected from the basket during a rough landing" and became caught in a rope and "dragged some way before the balloon came to rest and the basket tipped over".

Seven other passengers on the flight – described to the Herald as including "a couple of young blokes and their partners" - were quick to come to his aid and try to untangle the rope.

Sam Clark, of Adventure Balloons' ground crew - who had been following in the chase vehicle - was also on the scene.

"It was a pretty normal flight," he said.

"It wasn't until I got into the paddock that I realised something wasn't quite right. I took one look at Graeme and saw things weren't well.

"The passengers were unharmed, really helpful and everyone just got together and we got him free.

"It was good to have everyone there."

The Civil Aviation Authority (CAA) and WorkSafe have been notified of the incident. Photo / Kurt Bayer

St John was called at 9.10am and rushed to a farmer's field just off Lyndhurst Rd where the balloon basket was lying on its side.

The balloon did not crash-land, Clark said, and none of the passengers were hurt.

A rescue helicopter was scrambled and ended up flying Church to Christchurch Hospital in a serious condition.

This afternoon Clark said Church "will be a bit sore for a while" but was doing well and recovering in hospital.

Church had become engaged on Christmas Day, which Clark said he was "pretty stoked about".

TAIC is calling for anyone who saw the accident or observed the balloon in flight to come forward.

"We are particularly keen to receive photographs or videos," said Harald Hendel, the chief investigator of accidents.

Clark said they would work alongside any investigations but believed they would be "all sweet – it was just a freak accident".

Hendel said the commission has appointed a TAIC investigation team of two, who are travelling to the accident site today.

This afternoon, the balloon was still lying in the farmer's field, with the basket lying on its side.

"The investigation team's evidence collection work is broad to support the many routes that an investigation could follow," Hendel said.

"Over the next several days, TAIC's investigators will gather evidence about the accident scene, secure wreckage and electronic records such as photos, videos, and location data on the cellphones of the balloon occupants.

"We're interested in what the balloon occupants recall, along with the relevant professional and personal backgrounds of the pilot and other operator staff, what they knew, thought, experienced, and did.

"We'll be looking at the balloon, basket and other elements of the aircraft, its individual and type history, performance, maintenance, design.

"The operating environment is also of interest, including physical, weather, operating company safety system, organisational culture of the operator, traffic control, regulatory matters."

TAIC opens an inquiry when it believes the circumstances of an accident or incident have - or are likely to have - significant implications for transport safety, or when the inquiry may allow them to make findings or recommendations to improve transport safety.