Family and friends help search for missing 18yo bushwalker

Police are continuing an extensive search for 18-year-old Lily Hooper, who disappeared while hiking in Nattai National Park last Wednesday.

Investigators are examining phone data for clues to her last movements, while specialist crews continue searching the rugged terrain.

Police are trying to establish what equipment Lily had with her, whether she reached a nearby peak and whether data from her phone can provide further clues to her last movements.

The search for missing bushwalker Lily Hooper has entered its sixth day, with police using a thermal-imaging helicopter overnight and examining telecommunications data in an effort to trace her last movements.

The 18-year-old left her home south-west of Sydney on Wednesday morning to go hiking in the Nattai National Park in the Southern Highlands.

Her car was later found near the Bonnum Pic Walking Trail, but despite an extensive multi-agency operation beginning on Wednesday evening, there has been no trace of the experienced bushwalker.

Chief Inspector Brendan Bernie said crews continued searching throughout the weekend, supported by the NSW Police Air Wing, Rural Fire Service, State Emergency Service, Volunteer Rescue Association, mounted police and the trail-bike squad.

"We've also got Lily's family and friends with us, some assisting with the search and some are at the command post.

Police believe Ms Hooper had her mobile phone with her and are continuing to examine telecommunications information that could help establish where she went after arriving at the national park.

"We're also revisiting the telecommunications information that might be able to provide us a little bit of extra information. We suspect Lily had her phone with her and hopefully that might provide some information if that can be activated," Chief Inspector Bernie said.

He said police were still trying to establish what supplies Ms Hooper had with her when she set out.

"She left home not with obvious bushwalking equipment, but we suspect that there might have been some equipment in her car," he said.

"We're hoping that she took [it] with her. That will support her during this ordeal."

Police were unable to determine Ms Hooper's intended route beyond the Bonnum Pic Walking Trail and whether she reached a nearby peak.