“All flights will depart storm area prior to sunset, regardless of the degree of completion of the mission.
“Flight altitude while boxing the storm will be a minimum of five hundred feet absolute altitude, or at such higher altitude as will permit observations of the sea surface without hazard to safety. If contact flight cannot be maintained at five hundred feet, the legs will be flown a greater distance from the eye.”
The “boxing procedure” was used a great deal by the Air Weather Service in the early years but by 1954 it had been eliminated. The seven-hundred-millibar method was revised, and as used in flights out of Bermuda in 1954 was described by Captain Ed Vrable, navigator, in part as follows: “(1) The aircraft flies down wind at right angles to the storm path to a point of lowest pressure, about twenty miles directly in front of the eye; (2) Flight is continued down wind for three minutes beyond the low point and then the heading of the aircraft is changed 135° to the left; (3) The aircraft continues on this course until the pressure begins to rise and then turns 90° to the left and into the center.”
This new Air Force plan of flying into the hurricane at seven hundred millibars (ten thousand feet, roughly) is much like the Navy’s low-level method, except that the Air Force crews enter down wind across the front of the storm, but this is nearly always an advantage for aircraft based at Bermuda. From that island their most direct approach to an oncoming storm is into the front semicircle.
The Air Force has another aid in measuring weather in a storm. It is an instrument called a “dropsonde,” a specially designed apparatus which works on the same principle as the older “radiosonde.” A marvelously ingenious instrument, the radiosonde is a unit of very small weight containing miniature instruments for measuring pressure, temperature and humidity. It also has a metering device, a battery, and a small radio transmitter. The apparatus is carried aloft by a rubber balloon filled with helium. As the balloon rises, the radio transmitter sends signals for pressure, temperature and humidity at each level reached, and the signals are copied on a register at the ground weather station.