Figures from the Otago Rescue Helicopter Trust show steady growth in the use of hired back-up helicopters as the number of emergency missions increases.
The trust could be looking at leasing a second helicopter within the next two or three years, trust chairman Ross Black says.
In the year to March, the trust hired second and third back-up helicopters from Helicopters Otago to fly nearly 169 hours on emergency missions.
That compared with 128 hours the previous year and 34 hours in 2007, when the additional support option was first used.
The dedicated rescue helicopter flew 643 hours on emergency missions in the year to March.
Mr Black said the additional helicopters were hired most commonly during emergency overlaps when the rescue helicopter was busy on another mission.
Hiring extra helicopters on a casual basis was more expensive than using the trust's one fully dedicated machine, which was leased annually from Helicopters Otago.
If the trend for emergencies to overlap continued to grow, within two or three years leasing a second dedicated rescue helicopter would become more economical.
But it was impossible to know if the growth in rescue mission hours like that seen in the past few years would continue. The trust had to wait and see before making any decisions.
In the meantime, it had hired another rescue helicopter pilot, bringing to 3.5 the number of full-time trust-employed pilots dedicated to flying emergency missions.
"The relationship with Helicopters Otago has to have an appropriate commercial tension, and it does," Mr Black said.
"But, equally, the trust's commitment in terms of dedicated staff has to be in fairness to Helicopters Otago." Otago was "exceptionally lucky" the trust had access to Helicopters Otago head Graeme Gale's two other intensive care-capable helicopters in cases where there was an emergency overlap, Mr Black said. Few other cities had that capacity.
The trust employed two full-time St John paramedics, and others were available for flights if needed.
Mr Black said it was unlikely a dedicated intensive care-capable rescue helicopter would ever be based in Central Otago, as it was Government policy to have rescue helicopters based near major tertiary hospitals.
This year's Westpac Chopper Appeal raised $68,698 for the Otago Rescue Helicopter.
The Otago total was a 15% increase on last year and part of a record $1.66 million raised across the country, improving on the 2010 record figure of $1.45 million.
