Trans International Airlines, until now a charter airline, has announced it will begin low-fare, unrestricted scheduled air service to Europe in May.

The airline's proposed services take advantage both of the Civil aeronautics Board's encouragement of charter airlines to enter scheduled markets and recently signed bilateral agreements that allow the United States to grant different airlines the same international routes.

Trans International said it would begin its new services May 1 with twice weekly flights from New York to Amsterdam and once-a-week flights from Los Angeles to Amsterdam, with a stop to pick up passengers in Bangor, Maine.

The one-way fare between New York and Amsterdam will be $199 during the low season and $219 during the peak summer travel period; the roundtrip fares will be $259 during the low season and $319 during the summer months.

The fares TIA proposes to offer are about half the standard unrestricted economy class fares. Passengers will be able to obtain confirmed seat reservations and will encounter none of the minimum or maximum stay of advance purchase restricts -- and limitations on capacity -- that accompany most low-fare offerings, according to TIA. Passengers also will be served regular in-flight meals.

In addition to the Amsterdam service, TIA will begin weekly New York to Paris flights on June 19 and New York to Frankfurt service on June 24. The proposed fares, which must still get the required governmental approvals, are comparable to the Amsterdam fares.

The airline plans to use Super DC-8 aircraft for its one-class service to each destination.

The CAB recently has awarded a number of carriers new routes to Europe and expects travelers to be offered a whole range of new services by the summer vacation period.