CAMP PENDLETON, Calif. - About a dozen Marine aircraft will make a commemorative fly-over during a graduation ceremony for the final class of CH-46E Sea Knight helicopter crew chiefs Wednesday at Camp Pendleton's Air Station, Marine officials said.

The venerable Sea Knights have two sets of rotors -- forward and back -- and have been a familiar sight in San Diego skies since the Vietnam War era. But they soon will be gone from the skies.

They are being replaced phased out and replaced by the MV-22 Osprey, which has rotors on wing-like supports. Those blades rotate from helicopter-like orientations to airplane-style configurations while in flight.

Despite some publicized crashes, Popular Mechanics magazine calls the Osprey the safest Marine attack helicopter in combat operations.    At Wednesday's ceremony, Marine Medium Helicopter Squadron 164 will graduate the final class of personnel trained to operate the old choppers, according to the 3rd Marine Aircraft Wing's Public Affairs Office.

That squadron deployed the first squadron of CH-46E Sea Knights in Vietnam in 1968, and the helicopters have been flown since, earning a reputation as a workhorse, officials with the 3rd Marine Aircraft Wing  Public Affairs Office said.