The Harrier was attempting to land on the U.S. amphibious assault ship Nassau in the northern Persian Gulf at 7:40 p.m. local time.
The pilot, who parachuted into the water after ejecting, was listed in fair condition after being picked up by a Navy search and rescue helicopter. His name was withheld. The cause is under investigation.
The Harrier, which can take off and land vertically like a helicopter, routinely transitions into a hover before descending onto a ship's deck. The attack jet has a long history of problems. Tuesday's crash was the Marine Harrier's 144th major accident since the jump jet was acquired in 1971. It has amassed the highest accident rate of any plane flying in the U.S. military. Forty-five Marines have died in Harriers.
The Harrier also has a troubled combat record. During the 1991 Persian Gulf War, five Harriers were shot down by heat-seeking Iraqi missiles. Two pilots were killed and two others captured. The Harrier's loss rate was more than double that of the other leading U.S. attack and fighter planes.
The Marines said the Harrier was ready to play a significant role in the Iraq war, and that its problems were behind it. About 60 Harriers are on Navy ships in the region around Iraq.
At a Friday briefing, Defense Secretary Donald H. Rumsfeld aired a video of an AV-8B taking out an Iraqi tank with a missile.
British Harriers have flown hundreds of missions supporting troops and striking various Iraqi targets, according to Royal Air Force spokesmen. This has included hitting a mobile missile launcher and dropping satellite-guided bombs on a Baath Party headquarters in Basra.
The Harrier crash followed an accident earlier in the day involving a Navy S-3B Viking aircraft. The Viking veered off the flight deck of the U.S. carrier Constellation in the northern Persian Gulf shortly after landing. The two pilots ejected before the plane plunged into the sea. They suffered minor injuries.
On Monday, a Navy F-14 Tomcat fighter jet crashed due to a mechanical failure, the military disclosed late Tuesday. The two crew members were picked up by a rescue helicopter. Initial reports indicated that neither was seriously injured.
Wilkinson reported from Doha and Miller from Washington.