Humberside Airport is set to lose three popular holiday destinations to its newest rival, in Doncaster.
Doncaster Airport will be a base for Thomson's low-cost airline
Weekly flights to Faro, in Portugal, Corfu, and the Costa Blanca will depart from Robin Hood Airport in summer 2005, rather than North Lincolnshire.
Holiday operator Thomson is also to use the former RAF site as a second base for its low-cost airline, Thomsonfly.
Humberside Airport issued a statement saying discussions with operators about its 2005 routes were still ongoing.
It read: "The summer 2005 programme is very much in its infancy in terms of what may finally be available from Humberside in that period.
"We are currently in talks with all key tour operators with a view to finalising and potentially further developing the programme and, as such, will have a clearer idea in the coming weeks."
The Thomson website is currently showing availability for Corfu and Costa Blanca holidays in summer 2005, departing from Doncaster.
But a similar search of holidays departing from Humberside Airport yields no results.
A spokeswoman for Thomson Holidays said: "We remain firmly committed to offering holidays from Humberside airport and will still be offering a wide range of holidays for summer 2005.
"We regularly review the amount of flights we have from every airport and we have reduced the number of flights out of Humberside slightly."
Hull travel agent Andre Earle told BBC Radio Humberside the decision could be bad news for holidaymakers in the region.
"Essentially it could be the thin end of the wedge.
"I'm hoping that it isn't the case, because Humberside over the last 20 years has developed all sorts of regional flights that we could only dream of 25 years ago.
"If we do start losing flights it's going to mean more inconvenience - especially for people in Hull and Grimsby."
The Manchester Airport Group, which owns Humberside Airport, expressed its disappointment last year when the government gave the green-light for the Doncaster development.
Chief executive Geoff Muirhead said he believed that Yorkshire and the Humber region needed "more airlines, not more airports".