An Air Force helicopter is joining the search for the missing Polish tramper Jacek Grzybowski.
Inspector Mike Wright said the Iroquois helicopter would take to the air this morning to help Wellington police search and rescue.
Mr Grzybowski, a 28 year-old software engineer, went tramping in the RimutakaForest Park on Saturday and has now been in the open for five nights.
Mr Wright said the terrain was challenging, with dense bush.
"It's hard going for the search teams. It doesn't look far as the crow flies but it's taking some of the teams up to 12 hours to complete a tasking," he said.
Mr Wright said Mr Grzybowski was wearing sturdy clothing but did not have enough food for five nights out in the bush and police were concerned for his safety.
"We know that he has some alpine experience in Poland and has spent most weekends since his arrival in Wellington a few months ago exploring our tracks. It's possible however that he's under estimated the time required and the type of terrain he'd encounter in the Rimutaka Forest Park.
"Our fear is that he has slipped and fallen off a track and hasn't been able to make himself seen or heard," Mr Wright said.
He said search and rescue staff were now working against the clock as the weather was expected to deteriorate.
Mr Wright said anyone who has seen Mr Grzybowski should call: 0800 847 633.
He said police were in constant contact with the Polish Ambassador and community.
