Another issue connected to this still frame is the Brake Lights we see on the National Press Pool Car. Why if the JFK Limo & the Queen Mary are Moving and going underneath the Triple Underpass well ahead of the cars behind them, do we see the Press Pool Car hitting the Brakes? What is STOPPING/Slowing Down the Press Pool Car and the cars in Front of it?
This is, after all, the Press Pool Car. They may have felt the story was right there in Dealey Plaza, where the shots were fired. Other cars can take off if they want to but their reporter instincts may have been to urge the driver to stop. The driver’s responsibility was not to protect the occupants of that car, so he might oblige.
In addition, in heavy traffic, when one car brakes suddenly, the cars behind brake even more suddenly. Some of the cars behind may be forced to come to a stop even after the car that did the original braking never stopped and has now speeded up and is moving at its original speed. This can be observed anytime on any heavily congested freeway.
I believe that the JFK limousine slowed, from 13 mph to 8 mph, when the driver heard Connally yelling. So, he slowed so he could look backwards to figure out what, if anything, was occurring in the limousine. This was a mistake. He should not pause to figure out what is happening but instead assume something bad is happening and speed up. If it turned out to be nothing, no great harm is done.
By the way, I can expect the usual unsupported claim to be made, that the driver’s actions went against Secret Service training. No one knows what Secret Service training is. This has always been kept a secret because this information could be useful to would be assassins. For all we know, Secret Service training was to figure out what is happening and then act. Since much of the time, in a motorcade, the vehicles are hemmed in by crowds, a lot of the time taking off at high speed would not be a good option anyway. So, we don’t know if drivers were trained, before 1963, to always take off at high speed the moment something suspicious happens. Likely they weren’t.