Your grades8.txt file refers to results of testing your Time class using our driver program. You may need to run our driver program yourself before you fully understand the grades8.txt file. Please do so before asking grading questions.
No TimeTester.java: -10 points
Every class should come with a comment about its overall function. It needn't be a long comment (see Michael's solution), but something should be there nonetheless.
Many people got bounds-checking errors when we tested canceling seat 0 or 9 on the airplane. Remember to validate input!
On the airline program, quit is a menu option. Prompting "do you want to continue?" after every choice is unnecessarily demanding on the users.