Helicopter Locations - San Andreas

Helicopters are one of the best forms of transport in the game. They are ideal for using when taking over hoods, doing the trucking missions and taking girlfriends on dates (less crashing and more choice of location).

Many of these helicopters will be locked until you have competed the mission Learning to Fly (bronze pass in all the flying school tests).  The Maverick in Easter Bay Airport is unlocked (pilots license required to open gates though).

Los Santos

1. On top of Mad Dogs Crib a Sea Sparrow can be found after the mission A Home in the Hills (often does not appear, go away and try again).
2. On top of the Los Santos Tower in Downtown Los Santos (the tallest bulding with a star on the top). Accessible from the ground later in the game. 
3. Santa Maria Beach just south of the Safe House

San Fierro 

1. Easter Bay Airport 
2. The Helipad in Downtown San Fierro 
3. The Roof of San Fierro Medical Centre (San Flora)

Las Venturas 

1. Bayside Marina Helipad (near boating school)
2. Emerald Isle Casino Roof on The Strip (far north)
3. Verdant Meadows Airstrip after Up Up and Away Mission 
4. Sherman Dam
5. Shack and dock north of Verdant Meadows Airstrip 

There are also three other helicopters located in the three islands police departments (the West one in Los Santos).