1. Spawn an empty helicopter and get into it as a copilot
2. Take controls of the heli and start flying.
3. Press 'G' (the button to launch countermeasures), no flares will be deployed.
If you look in the top right corner, you wont see the amount of flares either.
4. Switch to a pilot seat, and see how you are able to deploy flares by pressing G and you can see how many flares are available in the top right corner.