During the past financial year, the trust experienced a 52% increase in flying hours for medical emergencies.
That came at a cost to trust, which recorded a $32,000 loss during that period, trust manager Ken Franklin said.
The loss was paid for using the trust's reserves. However, it was not a funding model the trust wanted to become reliant on.
''It's taken 15 years to build up the reserves the trust has got,'' he said.
''And it only covers about six months of operating costs, but every time we make a loss we are forced into paying for that loss through our reserves.
''But that's not a process we can sustain long term.''
A variety of complex factors had resulted in the increase of flying hours for medical emergencies, but the trust did not believe it was a one-off and expected the trend to continue.
The trust intended to provide ongoing assistance during medical emergencies but public funding was required to assist in making up the shortfall, Mr Franklin said.
''We have been able to negotiate an increase in the funding we get from the ministry [of Health],'' he said.
''They have increased their funding by $400,000 from next year.
''But we do have ongoing issues with our ability to fund this work.''
If everyone in Otago gave $5 each, the funding shortfall would be met, he said.
''Even $5 from an individual can make a real difference to us.''
Otago Rescue Helicopter Trust chairman Ross Black said the situation was further complicated by the need for a new helicopter soon.
''There's going to be a time in the next three to five years' time when it's going to be appropriate to replace that with a new machine,'' he said.
''It won't be the trust's intention to fund that machine, but it would be appropriate for the trust to play some part in that very significant replacement cost and the number is somewhere between $12 million and $15 million.''
Mr Black said he was proud of the service the trust offered and its reputation.
''It's become a key lifeline for all who work and live and play outside of the immediate confines of Dunedin,'' he said.
''This is a service that potentially benefits every single person in the region.''
He urged Otago's residents to contribute what they could to the trust.
