Five black African states opened a summit meeting today amid indications that they might throw their weight behind British attempts to break a deadlock in talks or bringing black majority rule to Rhodesia.

The five so-called front-line countries - Angola, Zambia, Tanzania, Mozambique and Botswana - support the black nationalist insurgency in Rhodesia.

Zambia President Kenneth Kaunda hosted the meeting at his heavily guarded presidential lodge, 10 miles outside Lusaka. Those present included Presidents Julius Nyerere of Tanzania and Samora Machel of Mozambique, and Botswana's Vice President Quett Masire. Angolan President Agostinho Neto sent his roving ambassador Pasqual Luvuala.

Also present were Rhodesian nationalist leaders Joshua Nkomo and Robert Mugabe, who head a hard-line grouping at the adjourned Geneva talks, and the Rev. Ndabanngi Sithole. The fourth nationalist leader at Geneva, Bishop Muzorewa, did not attend.

In Nairobi, British envoy Ivor Richard, chairman of the adjourned Geneva conference on Rhodesia, briefed Kenya foreign minister, Dr. Munyua Waiyaki, on the progress of his contacts with African leaders. Richard told reporters they had a "useful exchange of views." Richard said he would leave Kenya Monday for Lusaka.

Meanwhile, the Soviet news agency Tass reported that black nationalist guerillas in Rhodesia shot down a government military transport plane, killing threemen. The Rhodesian Defense Ministry said in Salisbury that three men died in the crash of transport plane on a supply drop mission in the southeastern border war zone last Thursday but said the crash was an accident.

Black Rhodesian guerillas are believed to have been armed; recently with Soviet surface-to-air antiaircraft missiles, but there has been no confirmed report of their use.