Police reveal how they found missing Canberra teen

Police in the ACT have revealed the techniques used to find a Canberra teen who survived on creek water for six nights after crashing her car in the bush.

Kathleen Bautista, 19, was discovered last week after police used mobile phone signals to pinpoint her location, The Canberra Times reports.

ACT Policing major crime leader (security intelligence) Ivan Naspe said police initially pinpointed signals between Ms Bautista's phone and Black Mountain tower.

Further analysis led to the discovery of a second phone tower at Isaac Ridge which allowed police to cross-check information and hone in on the student's location.

However, Sgt Naspe said the information can be "unreliable" and "is used as a guide only".

"In this case our guide indicated it was in the vicinity of the Black Mountain Tower," he said.

The search was then focused on an stretch of a road where Ms Bautista had crashed her car and led to her eventual discovery.

Navid Sobbi, who is managing director of National Surveillance and Intelligence, said every phone is in constant communication with mobile phone towers but at least three towers are needed to triangulate a phone's location and predict its location within a 50-100m radius.

"The more cell [towers] there are, the more accurate it will be…. If it's a more built up area, you'll get a more accurate reading, down to even 20 metres or 10 metres," he said.

Macquarie University Adjunct Professor Clive Williams said the case showed the importance of always carrying a mobile phone.