of the radioactive cloud; (2) total radiation dose on the flight; (3) radiation dose accumulated in transit of the radioactive cloud; (4) length of time required to fly through the cloud; (5) radiation dose ac cumulated on the flight back to base due to contamination on the aircraft; (6) maxim dose rate in the radioactive cloud; (7) dose rate in tbe crew compartment immediately after exit from the cloud due to contamination on the aircraft; (8) the rate of decay of this contamination; and (9) conditions of flight inside the radioactive cloud, i.e., turbulence and icing. “nee of these data, except the last, were recorded automatically with the instrumentation described in Section 2.2. The items of information desired from each flight and the instruments which were used to provide them are summarized in Tables 2.1 Most of the information was available directly from the installed instrumentation, while some additional information was obtained by indirect methods as indicated in Sections 2.3.1 through 2.3.9, It should be noted that these indirect methods constituted, in every case, a duplicate method for obtaining a check on the same data obtained by one or more direct measurements, In addition, the pilot (and observer when present) made observations during the flight on the following parameters; i) dimensions of the cloud at various altitudes prior to penetration; (2) time and altitude of penetration; (3) type of penetration; (4) length of tims in the radio- active cloud; (5) maximm dose rate in the cloud; (6) dose rate in the cockpit on exit from the cloud due te contamination on the aircraft; (7) accumulated dose in the cockpit at time of exit from the cloud; end (8) degree of turbulence and icing noted during passage through the radioactive cloud. These observations were reported to the flight director in the air and were transcribed from the pilot's and director's notes during the post-flight debriefing. These observations by the pilot duplicate information recorded automatically by the instrumsntation in the aircraft in all cases except icing conditions in the cloud. 23-1 Total Radiation Dose, The total radiation dose was measured directly by the Sigmatrons, quarts-fiber dosimeters, NBS film packs, and Rad-Safe film badges. It was also obtained by integrating the area under the dose-rate-versus-time curves yielded by the P-Meter and the Bioscel mounted in the photopanel, 203.2 Iength of Tims in Cloud. The pilot flashed the marker light on the photopanel at the times which he considered to be his entry and exit from the cloud. Time in the visible cloud was then computed by observation of the clock in the photopanel pictures, Time in the radia~ tion cloud was obtained from the P-Meter and Bioscel data. These two instruments provided curves of dose rate as a function of tims, For purposes of this calculation, the entry and exit were considered to be those times at which the dose rate was 5 percent of the maximum rate observed. 203-3 Radiation Dose in Cloud. The radiation dose received in the Cloud was measured by integration of the area under the P-Meter and Bioscel curves between cloud entry and cloud exit. The Sigmatron in the 19 PY BEST AVAILABLE CO