Latvia's transport ministry has formally put the national carrier, Air Baltic, on the market by inviting expressions of interest from potential investors.
The government holds a 99.8% stake in the flag-carrier and it is intending to offer 50%, minus a single share, to a buyer.
But the transport ministry says that it would consider "other transition structures" if this suited both sides' interests.
The ministry is inviting non-binding expressions of interest, to be submitted to financial adviser IBS Prudentia, by 1 November.
It states that the selection of an investor will be based upon the buyer's ability to support Air Baltic's long-term development, the investor's reputation and its access to financial resources.
"After the confirmation of the initial interest, all potential investors will be provided with a non-confidential investment overview," says the ministry.
Air Baltic has already decided to modernise its fleet with 10 Bombardier CS300 twinjets, under a letter of intent, and take purchase rights on a further 10.
Its current fleet of 29 aircraft includes 14 older-variant Boeing 737s plus eight Bombardier Q400 and seven Fokker 50 turboprops. The airline is aiming to operate a two-type all-Bombardier fleet comprising the CSeries jets and the Q400s.
Last year the Riga-based airline transported 3.4 million passengers and achieved sales of €150 million ($190 million) over the first half of 2012.