This question has come up frequently. Here are some answers I have posted before.
A new pilot figure created by our own Doug Cohen. It will come with a couple different head/arm options to make a Vietnam era pilot with SPH-5 helmet standing with an arm propped against his helo.
Trumpeter CH-47D crew. Set of crewmen and a couple of Soldiers for their CH-47D. The aircrew are wearing the current HGU-56 helmet as worn by the USAF and US Army crewmen. The Soldiers look like they could be used in any OIF scene as well. It also includes a display base and a cockpit for use in making a diorama.
Vietnam CH-47 Crew. Another set from Trumpeter.
It includes 2 seated pilots, a standing Crew Chief, and a standing ground crewman.
DML has a pretty nice Vietnam era crew. It comes in and out of production as DML sees a need for them (or something like that). They can be found from time to time on eBay as well, but can go for a high price there. They are now included in the Dragon (ex-Panda) UH-1D Huey kit as well.
Nemrod has a modern UH-60 crew and a couple of guys that look like a crew chief and a AF PJ:
UH-60 crew. A set of three crewmen and a few GIBs (Guys in Back) listed for UH-60s, but the pilots and crew chiefs have Vietnam era "Chicken Plate" armored vests. I have seen them advertised as a UH-1 crew as well. The soldiers look from about ODS era (late '80s to early '90s):
Same CMK set as a Vietnam era UH-1D/H crew, which they are more suited for due to their "Chicken Plate" body armor.
Vietnam UH Door Gunners. They look promising, sort of. The M60 gunner would be fitting for a UH-1B/C or an OH-6A as a free M60 door gunner. The other figure is a grunt with an M16A1 wearing an M1 helmet, not a door gunner at all.
Seated Vietnam Pilots.
US Helicopter Pilots, Standing
Verlinden made/makes a standing US Cobra pilot as well. Pretty good figure w/ flight suit and survival vest. It is closer to 1/32 (54mm) though, or he is a really tall pilot.
Coree (sometimes under the Dynasty or Legend names as well) has a set of 2 resin figures called UH-60 Helicopter Crew: 1 helmeted male w/ M4 carbine; 1 female wearing cavalry hat. It is kinda hokey, female is in image of Barbie, she doesn't look too realistic. Male is wearing nomex ABDUs (Aviator BDUs) though.
Kirin from China also had a couple sets, but both are long OOP. One was a set of Cobra pilots from ODS. The second was a set of crew chiefs loading ordinance.
ADV/Azimut has a set of Helo pilots listed as US Helicopter Crew for Huey, Cobra, Apache. They come with both the older, standard SPH-4 helmet and the IHADSS (Integrated Helmet and Display Sight System) for the AH-64 Apache. The set includes one seated and one standing pilot. They look pretty nice.
Evolution Miniatures out of Russia have recently released a figure listed as an American Helicopter Pilot, Vietnam as the first figure in a “Fight at Damaged Helicopter” series. Hopefully we will see more from them.
DToys out of Korea has a new USMC AH-1W Heli Crew out. They look pretty nice. The standing female pilot looks a little stiff though.
Also, some kits come with good crews.
UH-1C kits, you get a pretty good 4-man crew from Vietnam era.
OH-58D kits come with a good modern 2-man crew, probably the best modern ones out there. They also come with molded on seat belts as well. Very nice.
H-13 / Bell-47s come with good Korean war era pilot in leather jacket and patrol cap as well.
OH-6A comes with two guys form the DML Vietnam helo crew set too. The pilot with "WAR" on his helmet (Hugh Mills, actual pilot of Miss Claude IV) and the seated gunner.
LAPD MD-500 comes with a pilot and sniper in the back as well.
Bell-47 comes with a decent Korean-war ear pilot in leather jacket and ball cap-style hat.
UH-1B/C models also come with a decent 4-man Vietnam era crew as well. Not as nice as the DML or Academy ones, but still very usable.
There are also a few sets to fill up your Russian MI-24, MI-8, or MI-4 as well.
Russian Modern Heli. Pilots Standing, F35168
Russian modern Heli. Pilots Sitting, F35169
Modern Russian Helicopter Pilot, 35054F