Brazil's air traffic control is understaffed and lacks modern equipment, but travel is still safe, aviation authorities told Congress on Wednesday.
Lawmakers called the hearing to investigate a 6-month-old aviation crisis that culminated in a nationwide airport shutdown last month when about 100 air traffic controllers walked off the job.
Controllers returned to work after a few hours, but they have threatened to resign if their demands are not met. They want a pay increase, safety equipment upgraded and the system to be run by civilians not the military.
Several international aviation experts have cautioned about inadequate flight security in Brazil and one group said safety was as poor as in Africa.
But Defense Minister Waldir Pires disagreed.
"That is almost a provocation. Brazil has one of the best security records in the world," he told the hearing.
He later acknowledged that air control had staffing and equipment problems.
Air Force Commander Juniti Saito confirmed controllers' claims that parts of Brazil's airspace are not fully covered by radar.
But, he said, "Even when an aircraft is out of radar reach, it's being monitored. It is malice to say there are black holes in our control."
Saito said two of the four air traffic control centers had yet to be modernized and there was "occasional" atmospheric interference in radio communications.
The March strike renewed criticism that Lula had underestimated aviation problems that surfaced after Brazil's worst air crash in September.
Investigators say faulty radio contact may have contributed to the mid-air collision of a small executive jet and a Gol airlines Boeing 737 on September 29 that killed 154 people.
A subsequent shortage of air traffic controllers -- some were suspended and others on holiday -- caused widespread flight delays and cancellations, Saito said.
The air force did not take a position on demilitarizing the air traffic control system, but said it would be complicated because it required legal changes, equipment purchases and additional personnel.
"It's not easy to separate control," he said.
Air traffic in Latin America's largest country has grown, on average, by 17 percent annually for the past four years.
"Demand is growing faster than in China," Milton Zuanazzi, head of the aviation authority Anac, told the hearing.