The union's secretary Steve McGhie said there were no plans for industrial action, which would affect flying doctor services in the Wimmera.

There are between eight and 10 Royal Flying Doctor Service staff in Horsham, with the numbers fluctuating with demand.

Mr McGhie said the union had been disappointed with the service's refusal to give staff a pay rise in the collective

bargaining agreement, but hoped for progress on an agreement when the two parties met tomorrow.

"One of the major sticking points is they're not offering any percentage wage increases; we're only after 2.5 per cent," he said.

RFDS Victoria chief executive Scott Chapman did not comment on details of the negotiations, but said he was sure the parties could achieve a compromise.

"We are negotiating on a number of aspects of staff pay and conditions to reach agreement with our staff on a better-off overall position," he said.

"The flying doctors have a proud tradition of delivering services and we're confident of a positive outcome."

The union is preparing to enact work bans for members working at National Patient Transport tomorrow, with some staff set to refuse to carry more than one patient at a time.

While RFDS is responsible for primary patient transport arrangements in the Wimmera, National Patient Transport is often used by Ambulance Victoria in extreme conditions such as the recent heatwave and bushfires.

The union said it was concerned about transporting two patients at once and a risk of patients infecting each other.

NPT chief executive Jeff Wilson said the issue of double transporting patients only accounted for five per cent of NPT's activities, and the union had failed to raise it as an issue in previous negotiations.