I don't have the numbers to prove it, but I believe this is bogus. The author is probably comparing the average number of passengers over time to the number on these particular flights.
9/11 was a Tuesday, the lowest-volume travel day.
If you want a real comparison, you need to compare the numbers of passengers on 9/11 to the average number on Tuesday flights, not to the overall average.
Average number of passengers also fluctuates over the course of the year, and the middle of September may be lower than average.
We can see equally well into the past. That is, it gets real hazy and no two will agree completely what happened last week or even this morning. That is one thing.
Another thing is that the present is more of a period of time of about twelve seconds. All that is current events; although the period can be somewhat shorter it does not usually go longer. The subjective present includes a little of the objective past and the future—just a few seconds. That is from laboratory testing. Those who prophecy stuff such as Europe or America will be under sharia law in six years or a huge volcano will go off in the Northwest at some undefined time in the future are daydreaming.
I knew somebody was going to bring that up.
My cousin was late to work on 9/11 and is alive today because of that as she worked in one of the towers that was hit. It was unusual for her to be late.