If you are talking about Chris Ramsay's Airbender:-
First off, try and post a photo of how your fingers are positioned on the card to be thrown the moment RIGHT before shooting it.
This is how mine looks (so as to execute a beautiful Airbender, humble brag)
Now yours might not look the same when you execute a good Airbender. It differs. The entire trajectory and force of the card when thrown, depends solely on the position of the fingers at this crucial moment.
(EDIT: Unless your wrist makes the wrong angle. Make sure that the card ROUGHLY points in the direction it has to be thrown. I'm assuming however, that your problem is in your finger positioning, because that's what was the problem in my case, and it's slightly more difficult to correct than the wrist angle.)
At that position:-
1) If your middle finger is very close to your index finger then the card will be flung in a very non-desirable manner. It'll likely be flung straight down, with force or weakly. But remember, that the closer the index finger and middle finger, the more DOWNWARD your trajectory is likely to be.
2) You won't be able to fling the card at all if the middle finger is very close to the ring finger. If you do however (with tremendous difficulty), then it will just flop upwards and fall.
3) If your fingers are all close together, the force will be tremenduous and you'll achieve a great throw, but have zero control over it's trajectory.
4) The farther your fingers are, the weaker the throw will be. However, you'll have a lot of control over the trajectory and when exactly you want to execute the throw.
5) Of course, you want the fingers to be at a medium distance from each other. In my case, my index finger is closer to the middle finger than my ring finger. You'll find your sweet spot only after lots, lots, LOTS of practice with the 52 pick-up move (

). Those cards will travel everywhere except your other hand. Your nose might get a few papercuts in the process. That's NORMAL (although you might want to explain to your family how on earth you're getting all those marks on your face).
6) Typically, if you make sure (with the correct wrist angle) to keep your middle finger's second joint (the first 'bend' of the finger) situated right above the inner left corner of the card-to-be-thrown (the non-pip corner. Also, when I say ''above'' I don't mean that the middle finger is on the opposite face of the card. I just mean that laterally, it's upper to the inner left corner of the card. Check my picture for more details.).
7) Again, make sure that your wrist's angle with the other hand is a correct one. The card should be aimed towards the other hand, otherwise no amount of changing the finger positions will be of any help.
Lastly, as with all cardistry moves, do know that cards dropping to the floor, hitting the face, needing to be supported with the chin sometimes, driving you so crazy that you want to smash the deck through your ears into your brain, is almost like a rite of passage before mastering a move! But then hey, when you can be called 'that cool dude with the cards', I mean, it's worth it!
I hope this helps!
Cheers!
