Good luck, clever scripting, and the fact that one of the lead Flight Attendants was in cahoots.
DB - I'll respectfully disagree on the "clever scripting" verdict. Aside from the fact that the FLIGHTPLAN script was pretty bad, the most unforgivable aspect for something of this sort is that they CHEATED. In other words, there was no logic to it. No way, I repeat, no way would everyone have denied the existence of the child. Passengers saw her come onboard. The children sitting near her were staring at her.
So - two bits of HUGE illogic. 1. That they would deny seeing her when the did see her. And 2. That the villains would assume that nobody would see her. Quite the assumption! I get really angry at that kind of sloppy plotting. In the days when I used to write mysteries, we'd spend hours, days, making sure that it all added up when you looked back after the solution. I once did two backdoor mystery pilots (each a TV-movie) with the legendary Fred Silverman. It was a difficult but rewarding process. "And why would she do this when she could do that? But why would he take that car when this one was nearer? How would he figure this out when obviously"....etc. It wasn't enough to answer that the plot needed it! And trust me, by the time we were done there was not a hole in the plot. It all made perfect sense. Actually, the same thing with Aaron Spelling and his longtime associate, Duke Vincent. In that outing, we plotted about ten episodes of a mystery series we were pitching. Like putting together a puzzle. Hard work, but enormous fun. And what a learning experience!
Anyway, back to FLIGHTPLAN - who knows what happened to the script. Maybe what was originally there made perfect sense. So I won't condemn the writer.
End of rant. And speaking of writing - I must do some. Laters!
Speaking of "Laters!" - DR Uncle Jose - CONGRATULATIONS!!