(NewsNation Now) — While the weather seems to be cooperating during one of the busiest travel weeks of the year, more than just Mother Nature can cause airport delays.

Delays can be caused by anything from crew shortages to unruly passengers … but even a seemingly small wait time at the airport can have big consequences throughout the rest of the day.

For example, in a single day, one American Airlines A320 plane is making up to six separate flights, carrying up to 150 passengers on each leg.

If there is even a 15-minute delay early on, it will snowball to the point where the last flight of the day could be delayed by as much as two hours because of crew issues or missing takeoff slots.

Another factor that could cause flight delays is TSA checkpoints. If people can’t get to their gate, the plane is not going to leave on time. Travelers can use the myTSA app to check minute-to-minute delays at airports around the country.

Thanksgiving week is typically the busiest travel week of the year, with 2.2 million people being screened at security checkpoints across the country on Friday alone, according to the TSA.

So while it may be clear skies and smooth flights once you’re at 30,000 feet this week, getting to that point requires a lot of work on the ground and sometimes a little luck.