(Recasts and adds context)
By Raymond Colitt
BRASILIA, July 20 (Reuters) - Brazil's president pledged a thorough investigation into the plane crash that killed as many as 200 people in a televised address Friday that aimed to blunt criticism of his response to the country's deadliest aviation accident.
President Luiz Inacio Lula da Silva's appearance, the first since the crash on Tuesday, followed a flurry of complaints that Lula had been absent since the disaster to avoid jeopardizing his high approval ratings.
"Let our affection and solidarity help to alleviate the irreparable pain" of relatives and friends of those who died, Lula said. "The government is and will be doing all that is possible and impossible to find the causes of the accident."
Despite his warm words, Lula looked stiff and lacking the usual charisma that have made him one of Brazil's most popular presidents ever.
Earlier, a close adviser was filmed apparently celebrating reports suggesting the crash was caused by a mechanical error and not government negligence during a long-running aviation crisis.
Lula spoke after the focus of the investigation shifted from a faulty runway that could imply government responsibility to potential pilot error or mechanical failure.
Since the crash of an Airbus A320 EAD.PA at Sao Paulo's Congonhas airport, Brazilians have been clamoring for explanations and someone to take responsibility for the country's second major aviation accident in 10 months.
Lula, elected to a second term last year, had not made a public appearance or visited the crash site, unlike his longtime political rival, Sao Paulo state Gov. Jose Serra, who comforted mourning family members.
Marco Aurelio Garcia, a foreign policy adviser to the president, was shown on national television on Thursday making obscene gestures after news that pointed to problems with the braking system of the doomed A320.
Garcia apologized, saying it was his private expression of indignation at attempts to blame the government for the crash.
The opposition Brazilian Social Democracy Party said Garcia's gesture was "an offense to the Brazilian people."
The incident is the latest in a series of apparent blunders by members of Lula's Cabinet in the country's aviation crisis, which has seen chronic delays and flight cancellations.
Finance Minister Guido Mantega has tried to put a positive spin on the crisis, calling it a byproduct of Brazil's improving economy, and Tourism Minister Marta Suplicy said irritated travelers should "relax and enjoy."
Lula has a history of retreating at difficult times. During a previous aviation crisis that disrupted air travel at the end of last year, he took a beach vacation.
When he was booed during the opening ceremony of the Pan-American Games in Rio de Janeiro last Friday, he scrapped plans for a widely expected speech inaugurating the games.
The government announced measures on Friday to help reduce air traffic at the domestic Congonhas airport, including restrictions on charter flights and stopovers. It will ban new international routes to Sao Paulo and reroute flights from Congonhas to the city's international airport, Guarulhos.
Lula acknowledged Congonhas was overloaded and the air sector was "going through difficulties," but said Brazil's air travel safety was compatible with international standards.
The government also said it was studying the construction of a new airport in the greater Sao Paulo area.
TAM Linhas Aereas TAMM4.SATAM.N said late on Thursday the doomed aircraft had been flying without one of its thrust reversers, which help slow the plane at landing. But the company said the device, which was turned off after a malfunction last week, was not essential to safe landing.
TAM's chief executive, Marco Antonio Bologna, had said on Wednesday the aircraft was in perfect condition.
TAM initially said 186 people were on the flight but revised the figure on Friday to 187.
An Airbus spokeswoman in France said an A320 could fly for up to 10 days with a broken thrust reverser. Aviation experts say the device is complementary but not necessary to braking and that it is usually safe to fly without it. (Additional reporting by Isabel Versiani in Brasilia and Tim Hepher in Paris and Andrei Khalip in Rio de Janeiro)