The plans include a new multi-story car park and knocking down the 1937 arrivals building.
The building, which has already lost two floors due to safety concerns, has been called "unsafe" by airport bosses.
But Christopher Scholefield, from Save Jersey's Heritage, said plans to demolish the Art Deco terminal would be a loss to the island.
"Why is it that the interesting, genuine, historical, architectural artefact has to be knocked down in order to replace it on virtually the same footprint?
"If we ended up with what they're going to build... it won't be horrible, but we'll have something that's not genuine anymore."
Group chief executive officer of Jersey's airport and harbours, Doug Bannister, said: "It's actually not so original because it's been added to year after year... over the decades.
"It's an obstacle and what that means is it's too big and too close to the runway. It's currently unsafe."
Designs for redeveloping an airport "remove" its Art Deco past, a heritage campaigner has said.