The great transatlantic air fare war is escalating.

Trans International Airlines a large charter carrier, has asked the Civil Aeronautics Board to approve its no frills, transatlantic Skybus service between 14 U.S. cities and Brussels.

Trans World Airlines also filed an application with the CAB yesterday to match two lower fare New York to London services proposed last week by Pan American. Both the TWA and Pan Am plans offer roundtrip standby flights at $256, or $20 more than the no frills, Skytrain service provided by Laker Airways, as well as a budget excursion fare of $290 roundtrip. British Airways is also offering a $290 roundtrip flight.

Henry P. Huff, president of Trans International, which is based on Oakland, Calif., said his company's proposed fares would be less than half the cost of economy class tickets on existing scheduled flights. Sample one-way fares to brussels, on a confirmed reserved seat basis, would be $139 from New York and $229 from the West Coast.

The departure cities include Chicago, Los Angeles, New York, Oakland, Washington-Baltimore, Detroit Ft. Boston and Philadelphia.

Huff said none of the other budget services offered meet the travel needs of most American, because they must fly to New York and terminate their trip in London in order to take advantage of them.

TWA proposes to allocate up to 1,000 seats a week on regualr flights for both its budget and standby transatlantic services, according to a TWA spokesman.

Donald M. Casey. TWA's senior vice president for marketing said, "While we feel the Pan American fare is ill-conveived and will result in lower revenues rather than generate new passengers, we are matching it for purely competitive reasons."

Pan Am's budget plan must be purhcase three weeks in advance with the buyer permitted to specify the week, but not the day or time, of the flight.

Pan Am. TWA and British Airways intend to fly between John F. Kennedy and Heathrow Airports, rather than into the more remote Stanstead Airport used by Laker.