The Impact of the 9/11 Attacks on New York Air Travel

Provided Bureau of Transportation air travel statistics for a possible project for my Udacity course, there was only one idea that came to my mind. The effect of the 9/11 attacks on air travel.

I narrowed my focus to only New York airport activity for the month of September 2001.

This was all before the 107th Congress passed the Aviation and Transportation Security Act which President George W. Bush signed into law on November 19, 2001. As much as it seems like the TSA has always existed… it has only been around during the 21st century. 

Air travel did not even return to the August 2001 level until March 2004 (according to Bureau of Transportation statistics). 

I am only providing a snapshot of the normalcy before 9/11, the immediate impact and the start of the road to recovery by the end of the month.

Fig. 1: A bar chart depicting the total amount of airtime minutes for all flights arriving and departing every New York airport for the month of September 2001.

The first ten days established what was normal before the attack. Every day hovering between 138,000 and 165,000 minutes of airtime.

The attack grounded all flights for the rest of 9/11, all of 9/12, and nearly all of 9/13. It was a very slow beginning on 9/14.

By Monday the 17th, a “new normal” was attained and kept airtime consistent for the rest of the month. Basically between 100,000 and 120,000 minutes a day of airtime (just under 75% of the normal levels pre-9/11).

The implementation of much stricter security measures and the heightened anxiousness of travelers about flying contributed to operations being well below the pre-9/11 levels. 

Fig. 3 A look at the total number of minutes for delays/airtime, the number of (scheduled) flights and the number of canceled flights for each section of September.

There are stark contrasts that can be seen by dividing all of the data by section of month. One can see that for the days leading up to 9/11 (the 1st until the 10th) only 4.3% of flights were canceled. There were also considerably more arrival delays than departure delays for those days.

The second section of September beginning with 9/11 itself pushed the canceled number of flights up to 57%, and departure delays surpassed arrival delays.

For the third and final section of September, canceled flights drifted back down to 21.6% and departure delays were still higher than arrival delays. One can expect New York airports to have more departure delays than most other airports with the attacks coming on New York soil.

Now let’s look at canceled flights by day for the month of September 2001…

Just about what I expected…a ton of canceled flights on 9/11 and a few days after that. A “new normal” established around the 16th and less canceled flights since there were far less scheduled flights.

But something looks strange…

Let’s look closer, shall we?

Fig. 4 Number of daily canceled flights to and from New York airports for September of 2001.

That is an unusual number of canceled flights for September 10th…

Way more than all 9 days prior…why is this?

I looked it up on the internet…why so many canceled flights on September 10th? I found no information as to why this would happen.

Were any flights from 9/10 canceled because of 9/11? I don’t find this likely. This data only shows continental US flights, and all flights were grounded by 10am.

Was it a Monday thing? No. That explains nothing.

A flaw in the data?? Hmmm, there are no specific times in the data. It is possible that many canceled 9/11 flights were accidentally put in as 9/10.

A massive conspiracy????? Just stop.

References

1. Bureau of Transportation Statistics: https://www.transtats.bts.gov/Fields.asp?gnoyr_VQ=FGJ

2. A Look at How Airport Security Has Evolved Post 9-11: https://www.phl.org/newsroom/911-security-impact

3. BTS Twenty Years Later How Does Post 911 Air Travel Compare: https://www.bts.gov/data-spotlight/twenty-years-later-how-does-post-911-air-travel-compare-disruptions-covid-19#:~:text=All%20air%20service%20in%20the,to%20the%20August%202001%20level.

4. Timeline for the day of 9/11 attacks from Wikipedia: https://en.wikipedia.org/wiki/Timeline_for_the_day_of_the_September_11_attacks#:~:text=9%3A45%3A%20United%20States%20airspace,not%20permitted%20into%20the%20airspace..