U.S. and other airlines are considering legal actions against the British Airports Authority in an effort to reduce high landing charges at London's Heathrow Airport.

Considered out of line before by many airlines and governments, the charges were raised significantly by the British last April. It currently costs nearly $10,000 to land a Boeing 747 at Heathrow during peak hours -- at least double, and possibly triple, what it cost a year ago, airline officials contend.

According to an official of Trans World Airlines, its charges at Heathrow will total $16 million in 1980, up from $7.5 million in 1979.

The Heathrow charges include fees for landing, terminal use, passenger service, security and parking. In comparison with Heathrow, the more expensive of the European airports charge between $3,700 and $4,100 for comparable 747 services; some charge less than 2,000.

In the United States, the most expensive 747 landing is about $3,616 at New York's JFK Airport, while the same landing costs less than $1,000 at Dulles International here.

The reason Heathrow charges sky-rocketed this year is a relatively new British policy that limits the borrowing authority of the nationalized industries, including the airports run by the British Airports Authority. They also are being required to make a 6 percent rate of return on investment. tAs a consequence, the BAA is trying to finance future airport improvements, and possibly a new airport, through current user charges.

Each of the U.S. airlines operating at Heathrow -- TWA and Pan American World Airways -- has instructed its attorneys to determine whether it can file suit in the British courts alleging that the charges are unjust and unreasonable and in possible violation of the air services agreement signed by the United States and United Kingdom.

The agreement requires that airport charges be just and reasonable. They may reflect -- but not exceed -- the cost of the services provided and may provide for a reasonable rate or return on assets. The agreement also requires user charges to be based on sound economic principles and generally accepted accounting practices. Airline officials think the British policy and its implementation are subject to challenge on these grounds.

In a broader move, some of the airlines operating at Heathrow said in a statement they had decided last week at a meeting in London that they would join to take "legal and other action against the currently unacceptably high level of airport user charges."

One course of action the group will study is suing the Baa. Another proposal being considered is to do something to force the BAA to sue the airlines to collect the charges and, in the process, attempt to convince the courts that the charges are reasonable, one source explained. For example, there is some talk of paying charges at last year's level and putting the rest in an escrow account to be paid to the British authorities if and when they make a convincing case to the airlines that the increased charges are reasonable.

The International Air Transport Association, the organization of world airlines that functions both as trade association and a mechanism for fare-setting, also is trying on behalf of its members to reduce the charges.

So far, in meetings with representatives of governments and airlines, the BAA has stuck to its guns, according to participants. The BAA has invited representatives of airlines and airline associations to a meeting in London later this month which it has billed as "a 1980 review." One airline representative quipped that the BAA probably won't explain at the meeting what it already has done or announce a change in the policy but will deliver more bad news about next year's charges.