Newquay and Exeter airports are crucial to South West's economy, according to Unite, and the union warns that "a huge economic hole will open up" in the region if associated jobs disappear.
Unite has commissioned new research, which reveals that Newquay Airport generates £48 million per annum for the West Country, while Exeter Airport contributes £150 million.
Unite is now calling for urgent intervention from central government to give stability to dependent jobs at both airports, including crew, ground staff, engineers, associated retail, transport and other roles.
The union argues that any loans would need to come with strict conditions regarding executive pay, corporate governance, and should also include environmental demands to improve the industry's carbon footprint.
They also raise the possibility that a different public or public-private ownership model might be required in order for the airports to thrive.
Unite regional coordinating officer Terry Keefe said: "We are not asking for a giveaway, but for loans that will be repaid when the sector is back on its feet.
"It is more than two months since the chancellor promised that a support package would be forthcoming for aviation but he has yet to deliver. The communities that rely on Exeter and Newquay airports for jobs and their prosperity cannot wait much longer."
Newquay airport is set to reopen for passenger flights on 1 July with an Aer Lingus service to Dublin.
Other flights set for that week from the Cornwall Council-owned airport include services to London, Faro, Dusseldorf and Alicante.