As you level up in online gameplay for Grand Theft Auto 5, certain vehicles become inaccessible—no longer spawning as they regularly would. One such vehicle is the Cargobob helicopter, otherwise known as the largest and heaviest helicopter in the game.
If you're no longer able to spawn a Cargobob in GTA 5 and want one for your own, you can purchase one with a little help from YouTube user omgurheadsgone.
From your cell phone, head over to your internet and go to Travel and Transport. Visit the Warstock Cache & Carry website and click on any vehicle available so that the specific page pops up.
From that page, go up to the top left corner, press the home icon and then hover over the URL and either press A + B (Xbox) or O + X (PlayStation). Once you do that, you'll be able to change the URL and enter whatever you like. At the end of the URL, there should be a number. Erase whatever number you see and replace it with 5, then press Enter.
Once you press enter, you'll be taken to another page where you will now be able to purchase the Cargobob for $185,000.
It will now be added to the Pegasus list of vehicles that can be delivered to you, so you no longer have to worry about waiting for it to spawn.