"It's the chance to meet the pilot and crew and see the real people who are flying the chopper. They will show people the equipment they use and the procedures they go through to get to people when it's often a matter of minutes to save a life," said BayTrust sponsor liaison Nadine Rogers.
She said the main reason for the day was to raise awareness of the work of the rescue helicopter.
Other emergency services will also be giving demonstrations such as police dogs and armed offenders dogs and there will be a kids' area as well as coffee and food.
Members of the public will also have the chance to win a flight in the helicopter and there is a silent auction for other prizes donated by local businesses.
Gold coin donations will be gratefully accepted by the trust.
The details:
* What: Open Day BayTrust Rescue Helicopter
* Where: Rotorua Hospital
* When: Sunday 10am-2pm
* Cost: Free. Donations gratefully accepted.