What if I go on a flight and they where unsuccessful with getting my payment?

Obviously you WON'T 'go on a flight' if your ticket hasn't been paid for. This will emerge at the point where you go to check in.

What happened is the airline put a "Pending Hold" on the funds but did not submit the final charge. Because they haven't submitted the final charge your bank released the funds and made them available to you again.

Now, at some point the airline will submit the final debit and the bank will be required to deduct it again from your account. If you do not have the funds in the account you will be overdrawn at the bank and incur fees. At the very least you will incur a $30-$50 Overdraft fee for every overdrawn transaction. With most banks if you fail to take care of your overdraft balance in a few days you are charged more fees. If this goes on for a while they can close your account and put you into systems that will make it impossible to open a regular account again for several years. If you continue to fail to pay it back they may eventually sue you.

So can you get in trouble..you bet. As a result the best thing to do is just make sure the funds are available.

The computer says.....

Really does not matter what YOUR BANK says.

The agent at check in will say....

If they cannot determine the ticket is paid for you do not get on the plane.

That you want the accounts to credit debit instantly is not how it works, It can take a bit for the money to move around and be credited to your ticket/reservation.

At this point you have not PAID the Airline.They have lots of time before flight to cancel your booking.

If you have not actually paid, it is possible you will be refused travel on arrival at the airport. Best to check that your booking is still valid.

You "payed" for it? Not if you have a ticket - which I would check on.