Submarine-launched reconnaissance seaplanes were used to observe American progress in salvaging and repairing losses suffered at Pearl Harbor. Yokosuka E14Y1 aircraft, known as Glens to the Americans, were small biplanes with folding wings. They carried two men at a speed of 133 knots and were not armed. The first of these flights, from I-7, was undertaken on 17 December and a second, from I-19, on the night of 6-7 January. A third, from I-9, took place in February and was the prelude to Operation K, a second attack on Pearl Harbor.