Designed in 1913, the Avro 504 was fairly sturdy, easy to fly and one of the best British aircraft of the period. In addition to reconnaissance duties, it was used by the Royal Naval Air Service to conduct bombing raids into German territory at the beginning of the war. The Avro 504 was the first plane to strafe troops on the ground and it was also the first British plane to be shot down by enemy ground fire. Better aircraft soon replaced the Avro 504 in combat but it remained the standard British trainer for the duration of the war.
The characteristic that made the Avro 504 biplane instantly identifiable was the skid between its wheels. The purpose of the skid was to protect the propellor if the plane landed with its tail too high.