The search has resumed on Wednesday morning for a light plane missing near Murwillumbah in north-eastern NSW, after a resident in the area reported seeing an aircraft simply "drop out of the sky".
The single-engine plane took off from Murwillumbah Airport about 10am on Tuesday with only the pilot, a 72-year-old man, on board.
About 15 minutes later, a witness reported seeing a plane in difficulty near Limpinwood, about 25 kilometres west of the airport.
"Did anyone see a plane fall out of the sky about 1 hour ago around Limpinwood?," the man posted online.
Nine News also reported that a farmer in the area saw a green plane flying over his property that appeared to have its wing falling off.
In a statement, NSW Police said emergency services were alerted at 11am that the plane had disappeared.
"The ultralight plane was believed to have left Murwillumbah Airport about 10am, however it did not reach its destination," a police spokesman said.
"Police from Tweed-Byron Local Area Command continue to search for the aircraft."
The initial search focused on an area about 10 kilometres west of Murwillumbah, between Tyalgum and Chillingham. Residents reported the search then widened to also take in the area around Limpinwood and Crystal Creek.
The search area includes dense bushland, and it is understood the search has been complicated by the fact the ultralight is green, meaning it will be hard to spot in bushland.
Police and emergency service workers searched the area on foot and in vehicles, while two helicopters also scoured the area.
The search was called off about 6pm on Tuesday, and a NSW Police spokesman said it resumed at first light on Wednesday.
The Australian Maritime Safety Authority (AMSA) is co-ordinating the search.
An AMSA spokesman told Fairfax Media two helicopters were involved the search on Tuesday evening, including a Westpac Rescue helicopter from Lismore.
When that helicopter returned to refuel, a Queensland Government Air Rescue helicopter from Brisbane joined the search using night-vision equipment.
"Night vision searches depend on the conditions - the particular terrain they're looking at, [and] how the weather progresses," the spokesman said.