It sounds like you're suggesting that God might be sending you a personal message using a recurring number to warn you not to take a flight.
I vividly remember as a kid noticing the digital clock hitting 11:11 and getting excited because it's the only time that has four digits all the same (on a 12 hour clock of course). Guess what? I noticed the clock hitting that time more and more often as some part of my brain assigned some special importance to it, and subconsciously paid attention to the time. It was like magic, it would feel like I hadn't looked at the clock all day and then I would just happen to glance up right at 11:11. Our brains are truly a marvel and we understand so little of their capabilities.
I tend to think God speaks to us using a plethora of methods, but I am also wary of becoming trapped in one of The Sifters snares. It sounds like you have a growing feeling of physical threat without real evidence of such. Whose voice does that sound like?
Your question really has me thinking though, Rose. You could make a fear-based decision and stay home and be killed by your house collapsing, or you could ignore that persistent feeling and take the flight and meet a kindred spirit sitting next to you, or it could crash, or you could be the one to save the life of a choking child. Or all kinds of conclusions. I think everyone here gets that it's already determined and whether you live or die it's all according to His will and for His glory. But God does use "coincidences" to influence us into our choices, and I think you're wondering if this is an opportunity to prove your faith by cancelling the flight and then when the plane goes down in flames you'll praise him for His protection. Or is it Satan poisoning your mind with needless fear.
Maybe we should look back through the bible and see how often we are warned in the NT of any physical threats, and how often God makes a point of warning against spiritual threats.
My off the cuff thoughts? Go on the flight. If God doesn't want you on it you're taxi will break down or the flight will be cancelled or something, you won't be on it. It seems a lot more likely that His personal message to you will be about YOU, you're journey with Him, your spiritual growth.
Sorry this is so much philosophizing instead of scripturizing. Ya ya, autocorrect, I know that's not a word! I am not as good at pulling related scriptures out as some others around here are. I should probably work on that!
I hope this helps! -Vicki