West European airspace is becoming so congested that Europe's air transport system could come to a near standstill later this decade if something is not done quickly, according to a report published Tuesday by the International Air Transport Association.

The report, titled "A European Planning Strategy for Air Traffic to the Year 2010," was prepared for the association by SRI International, Menlo Park, Calif. It claimed that delays caused by congestion and other factors, such as 22 air traffic control systems in Europe and inefficient aircraft routings, cost some $5 billion a year.By the year 2000 annual losses to national economies owing to restrictions on air transport growth will be almost $10 billion, it added. Significant additional but non-quantifiable losses to commerce, industry and consumers will arise as air freight distribution costs increase and air travel becomes less affordable.

Robert Crandall, chairman of American Airlines, had used a prepublication copy of the report to support his call earlier in the week for a unification of Europe's air traffic control system and further deregulation of European air travel.

Speaking in London Monday at a conference to mark the launch of the World Travel Tourism Council, Mr. Crandall called for urgent top-level cooperation in making Europe's beleaguered air transportation system more efficient.

SRI similarly urged a major international conference of all governments, airlines and international aviation organizations to discuss ways of tackling the problem before it is too late.

It claimed that the expected doubling of European air traffic this decade

from 267 million passengers in 1988 to some 500 million and its trebling by 2010 to 740 million means that government spending of some $1.5 billion a year on air traffic control and airport facilities is inadequate to support either the existing commercial air transport system or future requirements.

The system will be unable to cope with increases in air traffic beyond 1995, SRI said.

SRI stressed that these problems are avoidable over the next 20 years, provided money and effort are applied. Sufficient airspace capacity already exists to accommodate growth, but only if it is organized efficiently and air traffic control systems and airports are operated efficiently.

However, beyond 2010 the system will be unable to cope unless new technologies are developed, it said.