clothing

You'll be just fine in knee length shorts at the airport and around town. You may feel out of place in business class though.

I wore comfortable jeans for my first flight in as it would be my first time meeting a boss or co-worker and it made sense to dress ready for anything.

The standard Islamic dress code for men holds that they should wear clothing that always covers the entire area from the navel to the knee. In practice, this would mean if wearing shorts, that they should come some way below the knee when standing, since when you sit down, they always ride up a bit. Any clothing that allows a man's thighs to be seen is forbidden (haram). So shorts that are knee-length would be right on the limit of what is acceptable.

Interestingly enough, many Muslim scholars also hold that it is prohibited for a Muslim man to wear clothing that extends down below his ankles (this is known as isbaal). This is why you will notice that members of the Committee for the Promotion of Virtue and the Prevention of Vice (often referred to as the religious police) normally wear thobes that are a couple of inches above the ankle.