Peking — At last month's session of China's National People's Congress, Air Force Chief of Staff Ma Zhanmin reported proudly that during a recent exercise in northern China not only had all the aircraft landed at the right place, but also they were on time.
Offered as an example of the progress of the People's Liberation Army (PLA), the episode in fact illustrates the serious problems that still plague the ''pillar of the proletariat.''
A little more than 30 years after its ''glorious victory,'' the PLA may be the weakest it has ever been.
According to Western military experts, the 4.2 million-strong army, the world's largest, keeps no comprehensive personnel records, lacks a clear internal hierarchy, and technically lags behind its potential enemies by more than 20 years.
Tarnished by the excesses of the Cultural Revolution, deflated by setbacks in battle, hampered by budget cuts, and purged by the moderates in Peking, it is the PLA that is now under attack.
The formation of a new Central Military Commission during last month's National People's Congress is the latest step in the reforms designed to purge the PLA leadership of its strong leftist influence and open the way for younger and better-educated personnel.
Although the PLA is no longer seen as a serious threat to China's modernization program and open-door foreign policy, it is still viewed warily by Deng Xiaoping and his supporters, as the last enclave of the left.
Despite publically expressing a wish to retire, at 79 Deng Xiaoping has not done so. This is an indication that he is not yet confident his successors would be well enough entrenched to withstand a challenge from the left.
For more than 12 months there has been a systematic campaign to isolate remaining conservatives within the PLA and emphasize the importance of youth and science above age and Maoist zeal.
Since last year the commanders of 6 of China's 11 military regions have been removed, more than 1,000 headquarter officers have retired, and another 10,000 officers have departed from the Peking garrison alone.
The average age of army commanders has been brought down to 50 years and for divisional commanders, to 45 years. The practice of automatic promotion of soldiers to the rank of officer has been abolished and replaced with educational requirements. Several military colleges and academies have been reopened or expanded, and more than 13,000 personnel from the PLA's general administration have been told to attend refresher courses.
The new Central Military Commission, headed by Deng Xiaoping and limited in its activities by the new Constitution and the civil bureaucracy, is designed to further reduce the power of the existing Communist Party military commissioners and remaining conservative generals.
These veterans still largely cling to Mao's concept of a ''people's war'' that relies on the PLA's massive size and revolutionary zeal, even though such tactics cost China heavily during its invasion of Vietnam in 1979. While China succeeded in capturing several key Vietnamese strongholds ''to teach Vietnam a lesson,'' it lost an estimated 20,000 lives to the technically superior enemy.
Soon afterward, during a period of particularly good relations with the United States, several Chinese generals were sent to Washington with a view to buying some modern equipment.
Although China has been developing its own nuclear weapons since the '60s, and according to Western experts has a nuclear force capable of reaching most of the Soviet Union and other parts of Asia, in operation, the entire army has only 12 armored divisions, the bulk of its 5,300 combat aircraft are obsolete, its surface naval fleet is antiquated, and of its 103 submarines, only two are nuclear powered.
It has been estimated that it would cost between $300 billion and $400 billion to bring China's defense equipment up to date. But Deng Xiaoping, while concerned with curtailing the political influence of the PLA, has insisted that military modernization take a back seat to economic development.
After two years of cuts, this year Peking held defense spending at last year's level of less than $9 billion.
In March of this year, China's minister for defense, Gen. Zhang Aiping, made it clear that China could not afford to import equipment but would have to rely on developing its own.
''China is a big country with a weak industrial base and small scientific and technical force. Thus modernization of the armed forces is a very difficult task. To do it by buying arms from abroad is unrealistic. We must be clearheaded. The only way is to rely on ourselves, on our own scientific and technical personnel,'' he said.
Soon after General Zhang's statement, China canceled a $150 million deal with British suppliers to refit its ''Luda'' class destroyers with Sea Dart surface-to-air missiles and advanced electronics. A plan to buy Mirage jets from France is also believed to have fallen through, and this follows a decision last year, by China, not to buy British Harrier jets, which performed well in the Falklands war.
''We must practice strict economy,'' said General Zhang in an article in the PLA's official newspaper, the Red Flag. ''And concentrate our efforts on the most key projects; we must pay attention to technical innovation. . . . The primary task of modernizing the armed forces is to develop and produce advanced weapons and equipment.''
At the same time the general, in the most explicit public emphasis on the development of China's nuclear industry so far, said China should be prepared for danger and ''use the present international atmosphere of relative peace to develop as quickly as we can new types of weapons and equipment to strengthen the modernization of national defense.''
China has had nuclear arms since the 1960s. It successfully tested a long-range intercontinental ballistic missile in 1980 and a submarine-based ballistic missile, from under water, last October.
It is not known how much China plans to spend on the development of nuclear weapons this year, as Peking refuses to reveal how funds are divided among military sectors and programs. But foreign experts here believe that a major portion of this year's $9 billion defense budget will go to China's nuclear program, as it seeks to develop second-strike capacity against the Soviet Union.
China's treaty of alliance and friendship with the Soviet Union, signed in 1950 and containing mutual defense obligations, expired in April 1980. And with a Soviet presence on three sides of China - in Afghanistan, Vietnam, and especially Mongolia - Moscow presents the greatest threat to the nation's security.
Foreign experts say that a credible nuclear deterrent fits into China's current goal of asserting an independent role in world politics and would allow Peking to be less dependent on the US nuclear umbrella.
According to a report by the CIA last September, even with increased spending , China's armed forces are likely to achieve only marginal progress by 1985 and to encounter serious problems in the future.
''Weakness in China's electronics industry will prevent the widescale introduction of new radars, sonars, and other electrical equipment; tactical, mobility, and logistical support will continue to be hampered by shortages of vehicles and by limited capacity for repair and maintenance. . . . Although new ground force equipment such as defense and anti-tank missiles will appear in limited numbers, their production will fall short (of needs),'' the report to the US Congress said.
Last month the PLA's chief of general staff, Gen.Yang Dezhi indicated that China was still interested in importing some technical know-how from overseas. ''We will rely mainly on our own efforts and at the same time introduce in an active manner advanced technologies from other countries to quicken our pace in improving and raising the level of modernization of the army's weaponry and equipment.''
So far the Chinese have not succeeded in opening the way to an exchange of high-level technology with the US. The pending visit to Peking this September by Secretary of Defense Caspar Weinberger will be another opportunity for the Chinese to press their case.
It appears, however, that Deng Xiaoping's strict rein on spending and purge of those opposed to China's liberal new policies are succeeding. Despite the discontent that the reforms must have stirred among all ranks of the Red Army, the last public indication of such resentment occurred last September. It was quickly dealt with.
Shortly before the party congress, the Liberation Army Daily in Shanghai published a strong criticism of the nation's reformist leadership and accused Deng of ''bourgeois liberalism'' and idealogical laxness. Immediately after the congress concluded, the paper was forced to publish a retraction, and the PLA's chief political commissioner, Wei Guoqing was replaced with the military technocrat, Yu Qiuli.
By May this year the Liberation Army Daily was carrying articles in favor of the reforms that are under way in the PLA, and by this month it was clear that the paper had got the message. In a radical break from its traditional loyalty to the Maoist military doctrine, the newspaper said in two major articles that Deng Xiaoping's views were in fact, the ''fundamental and guiding ideology'' of the PLA. CHINA'S MILITARY REGIONS Deployment of People's Liberation Army and locations of the Chinese Navy's regional headquarters URUMQI 60,000 troops CHENGDU 80,000 LANZHOU 90,000 troops 1 armored division KUNMING 60,000 troops PEKING 250,000 troops 4 armored divisions WUHAN 100,000 troops 2 armored divisions GUANGZHOU 120,000 troops SHENYANG 180,000 troops 3 armored divisions JINAN 90,000 troops 1 armored division NANJING 100,000 troops 1 armored division FUZHOU 60,000 troops The number of troops is an estimate based on 10,000 troops per main force infantry division. Field artillery and anti-aircraft divisions, miscellaneous units, and local militia forces are not included in these estimates.