Eastern Airways, a former franchise partner of collapsed carrier Flybe, has put its network on sale via its own website.
Tickets on Flybe services operated by Eastern Airways will continue to be honoured until end of tomorrow (Tuesday).
Four further new routes have been added to provide “continuity and regional protection”.
Travel agents can book Eastern Airways services directly as the airline returns to its original T3 flight code.
Eastern is taking on former Flybe services from Southampton to Manchester and Newcastle from Wednesday.
A daily through service from Southampton to Aberdeen will start commence on April 27, giving the carrier five routes from Southampton.
A new twice-daily Aberdeen-Birmingham route starts on March 16 after the launch of three of seven new routes from Teesside airport to Belfast City, Dublin and Southampton today (March 9) .
Flights to London City airport from Teesside start next month followed by seasonal services to Alicante and the Isle of Man to complement existing Aberdeen and Cardiff routes.
As a result Eastern Airways will have added 11 new routes in two months.
General manager commercial and flight operations, Roger Hage, said: “We are pleased to announce that our flights are now on sale as we’ve moved quickly to introduce a new booking system for Eastern Airways flights since becoming independent again.
“Our newly announced routes from Southampton to Manchester, Newcastle and Aberdeen, plus Aberdeen to Birmingham have already been well received nationally in recovering major lost connections which are now bookable at www.easternairways.com, along with our entire existing network.
“Delivering regional connectivity is vital for economic prosperity and regional development which supports our ability to provide a quality, cost effective and speedy service to meet the needs of both business and leisure travellers.”