As you know, with flights there are sometimes unforeseen circumstances that can lead to their cancellation. If you must board an aircraft, the probability of it happening is low; but not negligible. So if you travel regularly, it is inevitable that one day or another you will be entitled to this inconvenience. The disadvantage is that you will have to wait several hours, if you are not switched to another flight right away. It is therefore necessary to plan what not to be bored (book, tablet, Smartphone...). It should be noted that, contrary to what is believed, the reasons do not always involve weather or technical problems with aircraft. For American Airline, we created an algorithm nicknamed "The Cancellator". Teams of experts including meteorologists, airport managers and flight attendant supervisors regularly monitor flight variables. There are three main dimensions that are considered when cancelling a flight: customers, crew members and aircraft. Surprisingly, customers don't always come first. Why? Why? A flight may be fully optimized for customers, but the crew may not be complete (for various reasons). Often, the decision is based on profitability. If we realize that there are far fewer passengers than expected, the probability of cancellation is higher. A flight may have several stops and a cancellation of a connecting flight may result in another (if half of the passengers are missing and it is time to take off, the planned flight will be half as profitable). In addition, crew members will not be able to operate on subsequent flights. In short, we often get a flight cancellation in a chain.