This is one of those sections that is vague for a reason. It's to our advantage to not define these things in hard terms.

With FSB, you are not required to make any specific push times, nor is it defined where you will be at the airport or by what methodology they must be able to contact you. Common sense tells me that the employee parking lot is part of the airport and that my cell phone works as a means to contact me. If my phone isn't working, then I'll keep an ear out for a PA. If I hear it, I'll check it out.

Personally, I don't like to give an inch when it comes to interpreting the contract. If it's vague, I'll make my own interpretation and if the company doesn't agree, we can discuss it.