The volunteers' duties include picking up pilots from the airport, transporting their balloons, assisting with inflation and packing down, providing support during take off and landing, and making the overseas pilots feel at home.
"We show them around, like take them out to Castlepoint, or to the Tui Brewery," Mrs Gregory said.
While their trips mostly run smoothly, the volunteers are on hand for any emergencies.
"A pilot left his suitcase behind one year -- so one of our guys, Phil Logan, drove it up to Taupo for him."
Mr Gregory said the most difficult part of the job is inflating and packing down the special shaped balloons, usually thousands of cubic metres in volume.
"You need about 20 people," he said.
"You have to take off the velcro from all the panels, spread them out, and fill them with air individually," he said.
"Once you deflate, you need to roll it up tight, like a big sausage roll."
Volunteers must also be on hand to "rescue" the pilots if they land in unexpected places -- such as the middle of a farm.
"Sometimes, they've landed in paddocks full of cowshit, or we've had to cross three fields to get to them," Mrs Gregory said.
She said the volunteers have made close friendships with the international pilots, and they regularly keep in touch.
"Sometimes they'll send us Christmas presents and cards. You meet some interesting people . They are really friendly and nice."
This year's Wairarapa Balloon Festival runs from March 12 to 15.