Project Blue Book file, RB-47, July 17, 1957

Read from the scan by GLM-OCR; expect the odd misread word.

At 10:52Z, McClure 'had signal at 200 $ ^{\circ} $ relative bearing, moving up his D/F (direction finder) scope," according to the Piwetz account. For the calculated RB-47 position at that time, the bearing to Duncanville would have been $ 200^{\circ} $ , as McClure observed. And because the RB-47 was then making a left turn toward the direction of the ground radar, the bearing indication should have been moving up-scope, exactly as reported, if the S-band signal was coming from the Duncanville radar.

At 10:55Z, the Piwetz account says that the RB-47 crew notified Duncanville that the aircraft was running low on fuel and would soon have to head back to its Topeka base. [Chase now believes that this was done several minutes later than 10:55Z, but the discrepancy is not of consequence.]

At 10:57Z, the ALA-6 showed a signal with a bearing of $ 3 0 0^{\circ} $ . Based on the RB-47 position, the bearing to the Duncanville radar is estimated to be approximately $ 2 7 0^{\circ} $ . However, the airplane would have been turning at the time which would make it diffi cult for McClure to obtain a very accurate measurement.

Also at 10:57Z, the Piwetz account says that the Duncanville radar "had no scope contact" with the unidentified target. There is no further mention of ground radar contact after 10:57Z, yet the RB-47 continued to obtain its S-band signal, off-and-on, for another 40-odd minutes! THUS THE DUNCANVILLE RADAR HAD CONTACT WITH AN "UNIDENTI FIED TARGET" FOR NO MORE THAN SEVEN MINUTES -- between 10:48Z and 10:50Z, and again between 10:51Z and 10:56Z.

At 10:58Z, according to the Piwetz account, the aircraft commander "regained visual contact of object approximately 20 naut. miles northwest of Ft. Worth, estimated altitude 20,000 ft., at 2 o'clock from aircraft." [Chase has clarified the ambiguous language, explaining that it was the RB-47 that was northwest of Ft. Worth which would place the visual object south of Ft. Worth, as shown on Chase's original Airborne Observer's Report. My calculation of RB-47 position at this time, made with Chase's assistance, actually places the RB-47 west of Ft. Worth, not northwest.]

The Piwetz account contains almost no details of what happened during the next few minutes. RB-47 pilot Chase recalls that he obtained permission to dive toward the visual object (a light) and that the airplane went down to roughly 20,000 ft. Because the aircraft was maneuvering almost continuously during the next few minutes, McClure would have difficulty taking signal bearing measurements. This probably explains why there are no further S-band bearing measurements given by Piwetz until some minutes later when the aircraft gave up its chase and headed north toward Topeka.

By 10:58Z, darkness would be fast receding in the Dallas/Ft. Worth area. Accord ing to the World Almanac, official sunrise at Dallas on July 17, 1957, was 11:31Z (5:31 CST, or 6:31 CDT). The sky would be moderately light at least 30 minutes before official sunrise. The fact that the RB-47 crew abandoned their chase suggests that they did not find any unusual craft or object when they reached the area where the visual light seemed to be situated. Otherwise, we can assume they would have lingered longer and reported their sighting to Duncanville inasmuch as the RB-47 could have arranged an emergency landing for re-fueling at a nearby Air Force base.

According to the Piwetz account, the RB-47 finally took up a heading for home at 11:02Z, and by 11:40Z, the aircraft was roughly abeam of Oklahoma City. The 11:02Z time is believed to be a typographical (transposition) error, intended to be 11:20Z. This would be much more consistent with the 11:40Z time abeam of Oklahoma City and the aircraft's position at 10:50Z when it is known to have been near Dallas/Ft. Worth.