Brian Rudman: Noise moans just plane hysteria

Auckland International Airport is testing a "smarter'' flight path for jets. Photo / Greg Bowker

Opinion

Complaints over low-flying jets increase as more Epsom residents learn about trial of new flight paths

Over the past four months, a group of Epsom and Royal Oak residents have been working themselves into a right old lather over low-flying aircraft. The furore was sparked by a story in early May in the Central Leader about trial changes to the landing approach of planes flying in from Asia and Australia to Auckland International Airport.

As with the saga a decade ago over the ill-fated Auckland Botanic Gardens noise barrier, of which more later, my natural instinct was to sympathise with the "victims". But like the noise barrier, the facts point to the problem being mostly in the minds of the complainants.

The vast majority of the flights complained about as new and noisy were not part of the trial at all, but part of the normal procession of jets that have flown over Epsom for years.

With the advent of new navigational aids, a year-long trial began last October to reduce the distance flown over urban Auckland as planes came in to land. The "normal approach" is to come in from the Tasman Sea, north of the Manukau Harbour, and fly over Mt Roskill and Epsom to Howick before making a turn to line up with the approaches to the Mangere runway. The "smart approaches" trial involves planes making the turn over One Tree Hill and industrial Penrose.

From mid-October until the end of December last year, there were five trial "smart" flights each day and no complaints. Trials were then doubled to 10 a day. It was not until mid-March, 20 weeks into the trial, that a complaint was received. Another followed later in the month, and two in April. Two were from the same person. Following the initial May 3 news story quoting Epsom resident Toni Walker saying the noise was "really destroying the atmosphere in the area" and announcing a protest petition, complaints began flowing in. Television and newspaper reports continued, as did the complaints.

Marshall Day Acoustics was commissioned by Auckland airport to analyse the issue. It married the time and address of complaints with the flight data of all incoming flights and revealed the distorting power of mind over matter. "Of the 111 aircraft events complained of during April to June, 100 events (90 per cent) were aircraft on normal approach paths." Only 11 were smart approaches.

A number of Epsom complainants had claimed aircraft had not flown over their houses in the past. Historic flight path records showed "this is not the case". During prevailing westerly conditions "approximately 25-30 jet arrivals per day have typically overflown Epsom/Mt Roskill areas. This area has also been subject to a number of departure overflights".

The report notes that the normal approach over Epsom/Mt Roskill is 5000ft to 7000ft, whereas the smart approach overflies Mt Roskill at 5000ft and One Tree Hill suburb at 4000ft. However, the difference in noise level "is theoretically, 2 to 4 decibels - an only just perceptible difference".

Some complainants claimed they'd been woken by smart approaches in the early hours, but the trials took place only between 7am and 10pm. Somehow they'd missed the seven to 10 normal approaches that for many years had flown over Epsom/One Tree Hill after 10pm.

What annoys acoustician Chris Day is the campaigner who refuses to accept the evidence. "Once it is determined there is no real noise effect, it is very harmful for people to actively drum up action and raise people's sensitivity. People who were not previously annoyed by normal flights now will be. A lovely old lady phoned the complaints line saying the airport company was giving her cancer by having these smart flights flying over here - this is what she had been told. The activists in this case have the best intention but are unwittingly causing people harm."

To Mr Day, it's a replay of the Botanic Gardens fiasco. In January 2001, a $300,000 noise barrier was erected between the Southern Motorway and the Manurewa gardens. It reduced the noise in the gardens by 15 decibels, but a few residents on the other side of the motorway claimed the noise was bouncing across to them and making their life unbearable. After a two-year battle, the Environment Court backed the residents and ordered the wall ripped down.

For three weeks before and after the demolition, Marshall Day recorded noise levels at the homes of three complainants to measure any change. They wanted to prove a point and they did. In the Botanic Gardens, once the wall came down, the noise increased 15 decibels. But at the homes of the complainants there was no difference. In fact in two of three sites, the noise levels had fractionally increased. The barrier was proven not guilty.