A search is continuing for a missing pilot feared dead as air safety investigators probe what caused a rented light plane to crash in a national park.

Emergency services resumed their search on Friday morning after being hindered by poor weather and difficult terrain.

The crashed Cirrus SR20 took off from Bankstown Airport in Sydney's southwest on Thursday and appeared to be on its way back when an emergency location transmitter was activated about 4.30pm.

The wreckage was spotted from the air in the Budawang National Park, about 25km north of Batemans Bay on the NSW South Coast, about 5.30pm.

Rescuers were doing their best to traverse difficult terrain and access the remote location, NSW Police Inspector David Cockram told reporters on Friday afternoon.

"There's significant resources

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