I've been having some trouble evading the police when they start calling the helicopters out to spot me. Two stars and below it's pretty easy to flee in a car and either avoid the cops altogether or duck into some alleyway until they lose you.
Helicopters however, always seem to spot me when there's something (a building, a container, etc) between me and the helicopter. Sneaking or going into cover doesn't seem to help.
So what's my best bet for evading the all-seeing helicopter at higher wanted levels?
Best Answer
Head immediately for the nearest train track then find the nearest tunnel.
They show on the map as light grey lines. Tunnels show as a darker grey.
The helicopters can't find you in tunnels and in most cases if you get a good run down the tracks you'll have lost the cars too. On the off chance a cop car does make it into the tunnel with you it shouldn't be too hard to dispatch them as they can't surround you any more.
After that it's just a case of making sure you don't get hit by a train. They're very loud when approaching so that shouldn't be too hard either and then you're home free.
This is my tried and trusted method that has worked successfully right up to 5 stars.