Union chiefs are calling for assurances after the Evening Times exclusively revealed buy-out talks are ongoing for three airports -Glasgow, Aberdeen and Southampton.
All belong to London-based Heathrow Airport Holdings (HAH), which has Spanish transport infrastructure giant Ferrovial as its biggest shareholder.
Unite, the biggest trade union in the UK, says any takeover needs to be scrutinised to make sure the workforce doesn't lose out with possible cuts to pay, pensions and conditions.
Oliver Richardson, the national officer responsible for civil air transport, said: "We need to be kept closely informed of the sell-off process in the weeks and months ahead.
"Our concern is that there is no detrimental impact on our members' pay, pensions and terms and conditions due to any change of owner.
"We would therefore welcome the opportunity to meet any potential purchasers and to ensure their business plans for the future development of these three airports will benefit the airlines, workers and passengers."
But HAH officials won't make any pledges.
A spokeswoman said: "We can't comment because the process is at an early stage."