The plane, taking an expatriate Australian woman patient from Samoa to Melbourne, was running low on fuel after bad weather thwarted several attempts at landing on the island for a scheduled refuelling stop on Wednesday night.

The pilot-in-command, Captain Dominic James a Cleo Bachelor of the Year finalist decided to make a controlled landing on to the sea near the island and the Westwind jet, operated by Pel-Air for Careflight NSW, landed safely on the water. The plane sank within minutes, but the patient, her husband, two medical crew and two pilots evacuated safely and were later rescued by boat. The six clung to each other in the water because only three had time to grab life jackets.

Pel-Air Aviation chairman John Sharp said he was proud of the captain and first officer Zoe Culpit.

''Their professionalism stood out on the day and made a substantial difference to the outcome,'' he said.

''They executed what would have to be described as a perfect landing on water.

''The pilots ensured that the aircraft landed close to the coast, close to rescue.

''They landed at night, approximately we think about 9.30 local time, and as a result of the skill of the pilots the aircraft landed in the water and none of the passengers were injured.''

CareFlight spokesman John Badham said earlier reports the patient was critically ill were incorrect.

She was in a stable condition but required medical monitoring on the flight, he said.

Her condition did not appear to have worsened because of her time in the water.

She was scheduled to be transferred by air from the Norfolk Island hospital to Melbourne late yesterday or today when a suitably equipped plane was available, Mr Badham said.

The delay was not expected to significantly affect her condition, he said.

Norfolk Island airport manager Glenn Robinson said the passengers were shaken by their ordeal.

''They were extremely lucky and believe me, they all know it,'' he told Fairfax Radio Network yesterday.

''Full credit to the pilot. It was just an amazing effort by him.''

A new moon provided little light for the boat crew, but one rescuer eventually sighted the faint glow from one of the life jackets.

The Australian Transport Safety Bureau is investigating. AAP