> Interesting that there is a maximum rate.

Besides the other excellent reasons given, these sorts of clauses sometimes exist to protect the company. If the union has control over who works, as is often the case, they could choose to allow excessive overtime and make the airlines pay out for it regardless of whether circumstances really demanded it.

They don't usually do this because it's not in the favor of the union to keep people out of work. But there are always extraneous circumstances that could result in such outcomes, for example a national emergency that causes a shortage of pilots and those who stick around are contractually able to pull in ridiculous overtime while at the same time AA is restricted from changin flight schedules based on labor costs alone, etc.