The lawyer for the family of a pilot who crashed, killing himself and two passengers near Taupo, says there had been previous problems with navigational beacons on the approaches to the town's airport.
Steven Brown and Bernie and Christine Lewis died when their plane crashed into Mount Tauhara on the approach to the airport in February 2005.
At the Rotorua District Court on Wednesday the Brown family's lawyer detailed a list of problems experienced by Air New Zealand planes flying into Taupo.
Philip Grace says that from Air New Zealand reports, it appears there was a deviation in the directional beacon of up to 15% and this was happening 50% of the time.
Mr Grace says it included an incident in 2001 when a plane with 17 on board missed hitting Mount Tauhara only after pilots took visual control.
He says it appears the information was not shared outside Air New Zealand, or with regulatory agencies.
Coroner Wallace Bain says it is his preliminary view that if the problem had been fixed, the Mr Brown and the Lewises would not have died.
Call for overhaul of CAA
The son of a couple who died when their charter plane crashed into a Taupo mountain seven years ago wants a complete overhaul of the Civil Aviation Authority (CAA).
The inquest on Wednesday was told a blood sample indicated that it was possible the pilot had used cannabis within 48 hours of his death. Mr Brown also suffered from a heart condition.
Mark Lewis told Radio New Zealand's Checkpoint programme on Wednesday the Civil Aviation Authority needs to be overhauled and health regulations for pilots tightened.
Mr Lewis says regulations also need to be enforced and regularly reviewed.