system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If airline pilots can "make up" for delays by altering the route or the altitude, why not just do that in the first place?

I just landed in Philidelphia from Chicago, 10 mins after scheduled. However, we took off 35 mins late. The pilot mentioned that he will "fly slightly higher to make up for the lost time". If this shortens the path or speeds up the journey, why would this not be the default flight?
gpt
It may have cost a fair bit more in fuel - but the airline decided it was better to spend that and catch up so the plane would be in the right place for it's next trip in time and so the customers were happier.