As you may recall, our Lord died at 3 o'clock on that Friday afternoon. It has always been considered the hour of mercy.
Lots of things happen at 3:00 pm. BTW, was it 3:00 pm on the East coast or 3:00 pm where Jesus would have been at that time of day? I personally don't believe there is a particular "hour of mercy". It seems to be much more a "tradition" rather than a Biblical truth.
That Jesus Christ died at 3:00 pm may have some Biblical significance, one can hardly conclude that its part of the reason no one died in the controlled crash. I am a Christian and believe completely in basic tenets of the Christian faith.