Painted a bright orange, two members of the tribe emerged from their huts to threaten the helicopter as it flew low over their small village.
Others could be seen in the background, apparently startled by the presence of the noisy machine in their skies.
"We did the over-flight to show their houses, to show they are there, to show they exist,' said Jose Carlos dos Reis Meirelles, an expert on "uncontacted" tribes, who works for the Brazilian government's Indian affairs department.
"This is very important because there are some who doubt their existence."
Mr Meirelles said the tribe lived in six small communities, each with about six communal houses, in an area known as the Terra Indigena Kampa e Isolados do Envira, close to the Peru border.
In spite of the threat of the encroaching world, the number of Envira Indians is thought to be increasing, Mr Meirelles said.
But other "uncontacted" groups on the Peruvian side of the border, who have also been photographed by experts, were being pushed from their homes by illegal logging.
This could lead to conflict between the displaced tribes and an estimated 500 Indians already living on the Brazilian side, he said. Indians were also susceptible to contracting diseases from outsiders.
"What is happening in this region (of Peru) is a monumental crime against the natural world, the tribes, the fauna and is further testimony to the complete irrationality with which we, the civilised ones, treat the world," Mr Meirelles said.
Survival International, a group London-based group which defends the rights of tribal people, estimates there are more than 100 remaining isolated indigenous tribes worldwide, with more than half in either Peru or Brazil.
"These pictures are further evidence that uncontacted tribes really do exist," said Stephen Corry, director of Survival International.
"The world needs to wake up to this, and ensure that their territory is protected in accordance with international law. Otherwise, they will soon be made extinct."
© 2008 The Telegraph