An improved fleet of military cargo planes soon will allow the United States to carry troops or weapons to any corner of the world without landing in or flying over objecting countries.

Gen. William C. Moore Jr., head of the Military Airlift Command (MAC), which is responsible for delivering troops and cargo to world trouble spots in a hurry, said yesterday the Air Force is lengthening its reach by upgrading its C141 and C5 transport planes and building a bigger flying tanker.

The changes, he said will help avoid the types of problems encountered during the 1973 Arab-Israeli war, when only the giant C5s had the range to fly critically needed ammunition over the zigzag route from the United States to Tel Aviv.

Several Mediterranean countries, fearful of becoming embroiled in the war, refused to let American transports fly over on the way to Israel.

Since no Air Force cargo plane other than the C5 could be refueled in midair, denial of overflight rights in the Mediterranean meant that the workhorse fleet of 172 C141 transports could not make it to Israel.

But all this is changing.

MAC is adding refueling gear and enlarging the cargo space of the C141, and building a bigger flying tanker. Conversion of the C141 will be finished in 1982, Moore said, adding to the worldwide airlift now provided primarily by the 77 C5s now flying.

The C5, besides costing $2 billion more than anticipated, has turned out to be fragile. The Air Force is giving the plane stronger wings, which Lockheed shaved to keep down the plane's weight.

Moore blamed the plane's problems on the lack of "total integration of control" over design and manufacture. "The contractor cut back in some places" to meet the specifications in the contract, he said. " - don't think we can blame any one agency," he added, noting that both the Air Force and Pentagon civilians managed the C5 program.

"It was the first time we built an airplane that large," he said, and perhaps "we were trying to design an airplane to do too much."

Nowadays, the Air Force is treating the fragile-winged C5s like Dresden china, keeping close track of the flight hours on each until its wings are replaced.

Even with all its problems, the C5 is a gigantic improvement in the nation's ability to fly supplies to a trouble spot in a hurry, Moore asserted. He said 17 C5s could land as much stuff in Berlin today as 352 transports carried there in the airlift of 1948.

The lengthening reach of U.S. cargo planes, Moore said, has eased military problems stemming from having fewer bases abroad.

The outlook is not as bright, however, the MAC commander said, for retaining the people who fly transport aircraft. Pilots are leaving the Air Force at "an alarming rate" after completing their six years of obligated time, Moore said.

"It's not dollars in their eyes." Moore said, but rather a growing worry that military benefits are going to be taken away.

It costs taxpayers $257,700 to give one pilot the 18 months of training needed to fly an Air Force transport, according to service figures.

Besides losing this investment every time a young pilot leaves, the Air Force loses experience. "The accident potential increases," Moore said.

In contrast to recent years when the Military Airlift Command kept one of every three of its C141 and C5 pilots, with six to 11 years of flight time, the Air Force estimates that this retention rate this year will drop to one out of every four transport pilots.

Moore wishes for an end to the confusion among military people about the future of such benefits as retirement pay.

"There is a heavy air of uncertainty today," said, the 58-year-old general, a veteran of three wars.