The Messerschmitt Me 262 Schwalbe ("Swallow") was the world's first operational jet-powered fighter aircraft. Design work started before World War II began but engine problems prevented the aircraft from attaining operational status with the Luftwaffe until mid-1944. Compared with Allied fighters of its day, including the jet-powered Gloster Meteor, it was much faster and better armed. One of the most advanced aviation designs in operational use during World War II, the Me 262 was used in a variety of roles, including light bomber, reconnaissance and even experimental night fighter versions. Me 262 pilots claimed a total of 542 Allied kills (although higher claims are sometimes made) against the loss of about 100 Me 262s. The Allies countered its potential effectiveness in the air by relentlessly attacking the aircraft on the ground and while they were taking off or landing. Maintenance problems and a lack of fuel during the deteriorating late-war situation also reduced the effectiveness of the aircraft as a fighting force. In the end, the Me 262 had a negligible impact on the course of the war due to its late introduction and the small numbers that were deployed in operational service.