PARIS - New airline safety standards may be required after the crash of Air France Flight 447 cast doubt on the reliability of speed-measuring equipment in difficult, stormy conditions, French aviation investigators said yesterday.

The Airbus A330 plunged into the Atlantic Ocean off Brazil's coast June 1 en route from Rio de Janeiro to Paris, killing all 228 people aboard.

Many families of victims have expressed frustration with the lack of information over the last six months. In its second report on the crash, the French accident investigation agency BEA said experts still had little idea why the jet went down.

John Clemes, whose brother was on the flight, said investigators told the victims' families yesterday that the jet fell in less than five minutes.

BEA spokeswoman Martine del Bono did not return messages seeking confirmation, but the agency's study of automatic messages the jet emitted seemed to confirm that.

"Nobody on that plane itself was prepared for the crash," though the pilots battled to save the plane, Clemes said. "Some things were reset in the last minute, so they were obviously trying to desperately get the plane back under control."

Automatic messages sent by the plane's computers just before it crashed show it was receiving false speed readings from sensors known as Pitot tubes. Experts have that said running into a violent storm at either too slow or too fast a speed at high altitudes could be dangerous.

BEA said the safety standards used to certify plane equipment, particularly Pitot tubes, did not properly reflect high-altitude conditions. The report called for studies of cloud masses and icy conditions that may lead safety officials to modify the criteria.

Both the European Aviation Safety Agency and the U.S. Federal Aviation Administration ordered airlines flying Airbus jets like the one that crashed to replace their French-made Thales Pitot tubes.

"It's a shame that 228 people had to die before they take those problems seriously," said Clemes.

Investigators have repeatedly insisted that the crash was most likely caused by a series of failures and not just the Pitot tubes.

"It's true that there isn't enough known about the formation of ice crystals at high altitude and the impact that has on the Pitot tubes, for example," said Chris Yates, an independent aviation-safety analyst based in Britain.

Yesterday's BEA report does describe some potential clues about the crash. There were "powerful cumulonimbus clusters" on the jet's route, it said, and many planes flying in the area altered their routes to avoid the cloud masses.

Oxygen masks did not drop, and the plane did not depressurize, the report says. All the life vests found were still in their wrappers, suggesting perhaps that passengers had little or no warning. It also says the aircraft was probably in one piece upon impact.

The plane's black boxes are believed to be nearly 23,000 feet under water. The BEA report called for changes to flight recorders that should make them easier to locate.

Additional beacons should be fitted to commercial aircraft and the "pingers" attached to the black boxes should emit signals for 90 instead of 30 days, it said.

BEA also recommended studying the possibility of requiring software on planes that regularly transmits basic flight parameters.