WestJet and Kids

A mother and her young son were flying WestJet from Halifax to Calgary.  The son turned to his mother and asked, "If big dogs have baby dogs and big cats have baby cats, why don't big planes have baby planes?
     
The mother, who couldn't think of an answer that wouldn't lead to things she was not prepared to discuss with her young son, told him to ask the stewardess.
     
So the boy asked the stewardess, "If big dogs have baby dogs and big cats have baby cats, why don't big planes have baby planes?"
     
The  stewardess responded, "Did your mother tell you to ask me?"
     
The boy admitted that this was the case.
     
Well, then, tell your mother that there are no baby planes because WestJet always pulls out on time. Your mother can explain that to you."