Three airplanes, the NC-1, 3 and 4, used in this flight were designed and built through the joint efforts of the Navy and the Curtiss Aeroplane Company. These four-engined seaplanes, the largest built up to that time, exceeded the present-day Douglas DC-3 airplane in size and weight. Although sufficient fuel could be carried for a sixteen-hour flight, cruising airspeed was but eighty miles an hour. During the winter months of 1918 to 1919, plans were made by the Navy, in co-operation with the Weather Bureau, for securing as complete and widely distributed weather reports as possible for the Atlantic area immediately prior to and during the flight. Through international co-operation, observations were available from Iceland, Western Europe, Canada, and Bermuda. From this network of reports, it was possible to draw fairly complete weather maps and to follow in detail the various weather changes which might affect the flight. There were several special features that required consideration. For example, because of the heavy gasoline loads aboard the planes, it was necessary that the wind at Trepassey Bay be within certain rather narrow limits, strong enough to enable them to get off the water, but not so vigorous as to damage the hulls or cause them to upset. Similarly, the planes would need the help of a moderate westerly wind in order to reach the Azores on the first leg of the flight, but an excessive wind would cause rough seas, making an emergency landing extremely hazardous. Thus the problem was to select a day on which reasonably favorable conditions would be encountered, and to get the planes away as early as possible, to minimize the cost of maintaining the fleet at their positions. After four days of careful analysis and waiting, the Weather Bureau representative at Trepassey issued the following weather outlook on the afternoon of May 16, 1919: “Reports received indicate good conditions for flight over the western part of the course as far as Destroyer No. 12 (about six hundred miles out). Winds will be nearly parallel to the course and will yield actual assistance of about twenty miles per hour at flying levels. Over the course east of Destroyer No. 12 the winds, under the influence of the Azores high, recently developed, will be light, but mostly from a southwesterly direction. They will not yield any material assistance. “Weather will be clear and fine from Trepassey to Destroyer No. 8 (about four hundred miles out); partly cloudy thence to the Azores, with the likelihood of occasional showers. Such showers, however, if they occur, will be from clouds at low altitudes, and it should be possible to fly above them. “All in all, the conditions are as nearly favorable as they are likely to be for some time.”