Two Queensland brothers killed in a northern NSW plane crash are being remembered as experienced pilots who were passionate about aviation.

Robert Bryan Dull, 68, of Toowoomba and Owen Stanley Dull, 61, of Roadvale, south of Ipswich, took off about 2pm on Sunday from Casino Airport in a single-engine plane built by Robert as a "labour of love".

The pair were due to land in Boonah an hour later but never arrived.

In a statement their family thanked those involved in the search and recovery efforts in "difficult conditions".