There appears to be very little information available on this but most people would agree that the easiest way to find out, and go about this is to collect all of the hidden packages on the game. This should unlock the helicopter for you but if it fails then just try and get more information on it, and you never know, on your way to trying to get all of the hidden packages in the game you may be able to unlock the helicopter by chance, another way.
Now of course it's annoying when you've tried to do something on a game to get a certain result and you don't get that result, but you must be aware that the information you obtain on the Internet in regards to how to do things in games is not always completely true. This is why there are a number of things true gamers should do if they want the best and most reliable information.
The first thing to do is subscribe to official magazines. There are magazines out there that cover different games and different consoles, and these magazines will generally include feature sections that talk about how to do different things in games and how to achieve different things in games. From these magazines, too, you'll receive information that is mostly correct. Magazines after all do not risk publishing lies so you can be sure that you won't be wasting your time when you take the advice of magazines.
You can also use forums on the Internet. These have hundreds and sometimes even thousands of members, and whilst the information may not always be correct, you will have plenty of people to discuss options and give you ideas that come from their own experience on games.
Now of course it's annoying when you've tried to do something on a game to get a certain result and you don't get that result, but you must be aware that the information you obtain on the Internet in regards to how to do things in games is not always completely true. This is why there are a number of things true gamers should do if they want the best and most reliable information.
The first thing to do is subscribe to official magazines. There are magazines out there that cover different games and different consoles, and these magazines will generally include feature sections that talk about how to do different things in games and how to achieve different things in games. From these magazines, too, you'll receive information that is mostly correct. Magazines after all do not risk publishing lies so you can be sure that you won't be wasting your time when you take the advice of magazines.
You can also use forums on the Internet. These have hundreds and sometimes even thousands of members, and whilst the information may not always be correct, you will have plenty of people to discuss options and give you ideas that come from their own experience on games.