Why black unionists protest death of white S. African

Factories, assembly plants, and dockyards are to fall silent briefly today in South Africa. But the sound could be deafening to the South African government.

The half-hour work stoppage has been called for by labor unions to protest the death of union official Neil Aggett Feb. 5, who was found hanged while in police detention. The precise cause of death is being investigated.

Dr. Aggett's death threatens to unravel whatever goodwill the government has generated in recent years with ''reforms'' in the labor field that are generally regarded as well ahead of reforms in other areas. The thrust of government labor reform has been to open union organizing and registration to blacks.

But Dr. Aggett's death is viewed by many as an example of mounting government action against the increasingly black-supported trade-union movement that has emerged in recent years. Its emergence is partly a result of the government reforms and also one of the reasons the government was pressed to make the reforms.

The work stoppage could represent a significant show of unity among the new generation of trade unions. It may begin an era of involvement in issues that transcend ''bread and butter'' labor concerns.

In the long-term, analysts say there may be growing labor strife and confrontation if unions continue to feel threatened by the government and the government continues to see union officials as involved in activities that threaten state security.

Individual unions and federations representing an estimated 200,000 workers have indicated support for the work stoppage. Most of the workers are black. They include workers from automobile plants, dockyards, the metal industry, municipalities, and the food and canning industry in which Dr. Aggett held a union position.

''It is potentially a watershed,'' says industrial sociologist Eddie Webster of the University of the Witwatersrand. ''The trigger is that the state has fractured what was considered tolerable behavior by association with the death of a significant trade-union leader.''

Professor Webster says rank-and-file union members see Dr. Aggett's death as an assault on the emerging independent trade-union movement. These unions are not defined along racial lines, although membership is largely black. The unions tend to be suspicious of the government's registration and bargaining apparatus. Many of them increasingly prefer to bargain with individual employers at the shop-floor level.

''There is complete identification of these workers with Dr. Aggett, and that includes blacks,'' Professor Webster says.

The view of the death as a government attack on unions is not apt to be lessened if the death eventually is identified a suicide, Webster adds. The root of the objection is that Aggett was detained in the first place, he says.

Dr. Aggett is reportedly the first white, and the 46th South African, to die in detention under security laws since 1963. The most publicized case of death in police custody was that of Steven Biko in 1977.

The latest incident occurred against a backdrop of increasing numbers of detentions, particularly of union leaders. Perhaps anticipating the strong labor backlash the death would cause, two of South Africa's major employer groups speedily expressed concern over the death.

The Association of Chambers of Commerce of South Africa said the death could only ''complicate the evolution of sound industrial relations.'' The Federated Chamber of Industries said the case showed the ''unsatisfactoriness of long detentions.''

The practice of detention has come under scrutiny recently in South Africa. A government-appointed commission on security laws - the Rabie commission - recently called the indefinite-detention provision of the Terrorism Act a ''very drastic measure.'' The commission recommended measures for giving detainees more protection.

Its recommendations include: appointment of an ''inspector of detainees,'' allowing visits to prisoners at least once a fortnight by a magistrate and a district surgeon, and permitting visits by persons other than government officials.

Stricter controls on the length of detention were also proposed. The report suggests that detentions longer than 30 days should require the written authorization of a magistrate. After six months, police would have to go before a review board, presenting reasons for continued detention.

Even with these changes, the state would still be able to detain individuals indefinitely for interrogation, without bringing them to trial. And in this respect, John Dugard, director of the Center for Applied Legal Studies at the University of the Witwatersrand, says the Rabie commission failed to consider a key question: whether detention under current conditions amounts to ''mental torture or inhuman treatment.''