Summary

A USAF RB-47H reconnaissance bomber, tail number 53-4290, departed Forbes AFB, Kansas on a routine ECM (electronic countermeasures) training mission over the Gulf Coast. The crew of six — pilot Maj. Lewis D. Chase, co-pilot Maj. James H. McCoid, navigator Maj. Frank McClure, and three ECM operators — encountered an unknown object that was simultaneously detected by airborne radar, visually observed from the cockpit, and recorded as an active S-band signal source by the on-board ECM equipment. The pursuit lasted approximately 90 minutes across Mississippi, Louisiana, Texas, and Oklahoma — 700+ nautical miles. Ground radar at Duncanville, Texas confirmed independent tracking. The case was selected for inclusion in the “best evidence” submission to the 1968 Symposium on Unidentified Flying Objects before the U.S. House Committee on Science and Astronautics. USAF Project Blue Book closed it as “natural electromagnetic phenomena and a misidentified airliner.”

Consensus Narrative vs. Documentary Record

Clues Often Missed

1. Three independent detection systems fired simultaneously. Airborne radar (APS-23), ECM equipment (S-band), and human visual observation. No conventional explanation accounts for all three coinciding without a discrete physical source. Atmospheric refraction does not cause visual cockpit observation. Bird artifacts do not produce S-band returns at 2,800 MHz.
2. 2,800 MHz is Soviet ground-radar territory. The S-band signal was detected at 2,800 MHz — a frequency used by Soviet Mainstream search radar of the period, NOT by any American or commercial aviation system. American Airlines DC-6s did not transmit S-band. The signal source identification is incompatible with the official “DC-6” misidentification hypothesis.
3. Commercial aircraft do not pursue military bombers for 700 miles. The pursuit covered 700+ nautical miles across four states. American Airlines DC-6s of the period operated scheduled passenger routes, not 700-mile pursuits behind military aircraft. The hypothetical DC-6 does not appear in any flight log produced for the case.
4. The pilot never amended his account. Maj. Lewis Chase — the pilot — spoke on record about the encounter for years afterward. He never amended his account. He was a professional combat pilot, not a UFO advocate. The same is true for ECM operator Maj. Frank McClure.
5. Dr. James McDonald rejected the official conclusion on physics grounds. Dr. James E. McDonald’s 1969 reinvestigation, based on the original ECM tape recordings, radar logs, and crew interviews, found multiple irreconcilable problems with the Blue Book conclusion. McDonald was an atmospheric physicist with no UFOlogy background. He was lead author on three Senate statements on UAP.
6. The Condon Committee classified the case unknown. The Condon Committee (Univ. of Colorado, 1968) selected the case for inclusion in their “best evidence” presentation, classified it as “unknown” in their internal analysis, and then publicly downplayed it in the released summary. The internal/external discrepancy is consistent with the same pattern observed in Lubbock Lights (Battelle “unknown” vs Blue Book “moths”).
7. The ECM tape recordings still exist. Physical evidence of the S-band signal — the actual ECM tape recordings made aboard 53-4290 on July 17, 1957 — has been the subject of multiple FOIA requests and is reportedly still in archival storage at the National Archives. They have never been publicly released.

Open Threads

• The ECM tape recordings made aboard RB-47H 53-4290 on July 17, 1957 — physical evidence of the S-band signal — have never been publicly released.
• The Duncanville ground radar logs remain partially classified.
• The full Maj. Frank McClure debrief regarding S-band identification has not been released.
• The 1968 Condon Committee internal correspondence regarding the case classification is partially redacted at the University of Colorado archives.

Primary Sources

• Project Blue Book File: RB-47 (July 17, 1957)Declassified, NARA Record Group 341.
• Dr. James E. McDonald — RB-47 Reinvestigation (1969)Univ. of Arizona Atmospheric Sciences. Peer-reviewed critique of Blue Book conclusion.
• Condon Committee Report — Scientific Study of Unidentified Flying Objects (1968)Univ. of Colorado. Internal classification: unknown.
• 1968 Symposium on UFOs, U.S. House Committee on Science and AstronauticsCongressional record. Case included in best-evidence submission.
• Maj. Lewis D. Chase interviews and depositionsNICAP and CUFOS archives, multi-decade record.
• Capt. Edward J. Ruppelt — The Report on Unidentified Flying Objects (1956)Institutional context for the post-Blue Book investigation pattern.