In the context of the Local airport's current situation, where it serves $15,000$ passengers daily, employs $150$ full$-$time and $128$ part$-$time employees, and has several IT system components, including Passenger, Airlines$/$Flights$,$ and employee databases, as well as Processing$/$Computing and Long$-$term data storage. Assume you have been tasked with performing penetration testing to identify potential vulnerabilities before hackers can exploit them.

Please explain which penetration testing approach, among White Box Testing, Black Box Testing, and Grey Box Testing, would be best suited for this airport's case. Provide a detailed explanation of your choice, considering the specific characteristics and requirements of the airport's IT environment