 Part of the subsequent NTSB investigation focused on the fact that the instrument approach at the destination airport was not legal for night landing, and the overall pressure applied on the charter company and flight crew by the charter customer to complete the flight into the original destination.According to witnesses, the charter customer, upon learning that the flight might have to be diverted to an alternate airport due to the night landing restriction, had his business assistant call Avjet management, to "let them know that the airplane was not going to be redirected".In addition, witnesses claimed that when the charter customer learned that the captain had discussed the possible diversion with some of the passengers waiting for the late arrivals, he had his assistant call Avjet to instruct the captain to "keep his comments to himself".