Helicopters are an icon of Los Angeles. The city's large size, bad traffic and sometimes rough terrain make helicopters a practical way to get around the city quickly for public safety, news and medical personnel.
Police
Most, but not all, of the police helicopters in the area have a registration number that ends with "PD" or "LA". The Eurocopter AS350 is the most popular model among police agencies, with the occasional Bell 206 and MD500 showing up as well.
LAPD
LAPD Eurocopter AS350 
LAPD Bell 206. Photo by Christopher Ebdon,
LAPD alone has almost 20 helicopters, making its Air Support Division the largest municipal airborne law enforcement operation in the world, and there are almost always at least two, and sometimes three, police helicopters on patrol at any given time. Most of LAPD's choppers are Eurocopter AS350s but there are also a few Bell 206 models in the fleet. LAPD uses two different paint schemes: A two-tone, dark blue and silver, or a newer scheme reflecting the traditional black and white patrol car.
Most of LAPD's aircraft are based out of the Hooper Heliport.
Burbank/Glendale
Joint Air Support MD520. Photo by nickdryz,
The Burbank and Glendale police have a joint Air Support unit that flies 3 MD520 helicopters, which often fly over the northeastern parts of LA, like Eagle Rock. Their helicopters have a distinctive look and sound due to their lack of tail rotor blades.
Los Angeles County Sheriff
LA County Sikorsky UH-3H Sea King. Photo by Jeff. 
A Eurocopter AS332 Super Puma. Photo by Jerry Gunner.
LA County Eurocopter AS350. Photo by Steven Straiton.
The LA County sheriff has more than a dozen helicopters, mostly Eurocopter AS350s. They also have a Sikorsky UH-3H Sea King and a Eurocopter AS332 Super Puma that are suitable for rescue use. The sheriff's aircraft have a green and gold color scheme, with a lime green and yellow stripe.
LAFD
LAFD AugustaWestland AW139. Photo by Chris Yarzab.
LAFD Bell 206. Photo by B Garrett.
The Los Angeles Fire Department has at least a half dozen helicopters they use for rescue and firefighting. They use the Bell 206 and the AugustaWestland AW139 in a red and white color scheme. Many of their helicopters have registration numbers that end in "FD", including N301FD, N302FD, N303FD, N305FD and N306FD.
Children's Hospital Los Angeles
A Sikorsky S-76. Photo by ykanazawa1999.
Children's Hospital Los Angeles, near the intersection of Sunset Blvd and Hollywood Blvd, sees hundreds of helicopters taking off and landing from its rooftop heliport every year. The hospital has two dedicated helicopters, N615D and N323CH, which are both Sikorsky S-76's with a Children's Hospital logo on the side.
See also
"Why Is That LAPD Helicopter Circling Overhead?", LA Weekly 2/21/2014.
