The expansion means BA customers now have access to 38 of Loganair’s UK routes via ba.com.
Additions include Aberdeen to Belfast City, Birmingham, Bristol, Manchester and Southampton; Derry to London and Liverpool; Newquay to Manchester plus Inverness to Birmingham.
BA customers travelling from Aberdeen or the Isle of Man to Manchester will also now be able to connect onto Aer Lingus services to New York, Barbados and Orlando.
The agreement comes as Loganair celebrates its 60th birthday, making it the oldest UK airline still operating under its original name.
Loganair chief executive Jonathan Hinkles said: “We’re delighted to mark Loganair’s 60th anniversary with the expansion of our partnership with British Airways.
“The development cements what we believe to be the longest-running relationship between two UK airlines, and it’s a partnership which will continue to deliver for customers throughout the UK.”
Customers who book onto routes operated by Loganair through ba.com earn Avios and Tier points as part of British Airways’ Executive Club programme.