Does 'At 9:32, a hijacker, probably Jarrah, made or attempted to make the following announcement to the passengers of Flight 93:Ladies and  Here the captain, please sit down keep remaining sitting.' serve to directly refute the premise presented in 'Jarrah succeeded in convincing the passengers to stay calm thanks to his efforts at 9:32.'
At 9:32, a hijacker, probably Jarrah, made or attempted to make the following announcement to the passengers of Flight 93:Ladies and  Here the captain, please sit down keep remaining sitting.###Jarrah succeeded in convincing the passengers to stay calm thanks to his efforts at 9:32.