The RB-47 electronic intelligence case file centers on a July 17, 1957 Air Force reconnaissance-training flight whose evidence chain later passed through Air Defense Command, Air Technical Intelligence Center, Project Blue Book, the University of Colorado UFO Project, James E. McDonald's AIAA reconstruction, and subsequent archival scans.1234567
File Provenance
The National Archives identifies Project Blue Book as the declassified U.S. Air Force UFO investigation record set, with chronological case files available through 94 rolls of 35mm microfilm and supporting finding aids indexed by sighting date and location.1
The Black Vault's RB-47 Project Blue Book entry publishes a 57-page scan of the case-file material and describes the incident as a July 17, 1957 RB-47H encounter during a 55th Strategic Reconnaissance Wing training mission from Forbes Air Force Base.23
The scan preserves the Project 10073 record-card layer, Air Defense Command correspondence, the Airborne Observer's Data Sheet path, and the later Blue Book closure material that made the file traceable after the original 1957 handling became difficult to reconstruct.3457
McDonald's AIAA article states that the surviving file components included a three-page TWX from the 745th ACWRON at Duncanville, Texas, a four-page summary by E. T. Piwetz of the 55th Strategic Reconnaissance Wing, and a 12-page Airborne Observer's Data Sheet prepared by Major Lewis D. Chase on September 10, 1957.45
McDonald further states that the ADC-to-Blue Book forwarding on November 17, 1957 was evidently Project Blue Book's first notification of the case, while his article also notes that the University of Colorado study initially failed to locate the case files because the date had been misindexed or misread.456
Flight and Observers
The event originated during a composite RB-47 mission involving gunnery exercises over the Texas-Gulf area, navigation over the Gulf of Mexico, and electronic-countermeasures work on the return across the south-central United States.45
The crew named in McDonald's reconstruction was Lewis D. Chase as pilot, James H. McCoid as co-pilot, Thomas H. Hanley as navigator, John J. Provenzano as No. 1 monitor, Frank B. McClure as No. 2 monitor, and Walter A. Tuchscherer as No. 3 monitor.45
The most important instrumentation distinction is that the RB-47's direction-finding receivers were passive ELINT receivers rather than radar transmitters, so their relevant role was receiving and bearing-analyzing external radar-like signals rather than painting an object by reflection.458
McDonald's account identifies McClure's No. 2 system as an ALA-6 direction-finding receiver feeding APR-9 and ALA-5 equipment, while Provenzano's No. 1 position used an APD-4 direction-finding system and Tuchscherer's lower-frequency No. 3 monitor did not become a central signal channel.45
Multi-Sensor Chain
The first reported ELINT anomaly occurred shortly after the aircraft crossed the Mississippi coast near Gulfport, when McClure's No. 2 monitor detected a radar-like signal later characterized around 2,995 to 3,000 Mc/s, two-microsecond pulse width, 600-cycle pulse repetition frequency, four-rpm sweep rate, and vertical polarity.458
The direction-finding behavior mattered because McDonald says a fixed ground radar approached from one side should move down-scope as the aircraft passes, while McClure's initially observed signal moved up-scope and then across in a way he judged inconsistent with a simple fixed ground source.45
At 1010Z near 32-00N, 91-28W, Chase and McCoid reported a very intense white or blue-white light crossing rapidly from about the 11 o'clock position to the 2:30 position before disappearing.45
After that visual passage, McClure reacquired a strong roughly 3,000 Mc/s signal from the same relative bearing where the light had disappeared, and Provenzano's No. 1 monitor also reportedly acquired a signal from that bearing after equipment checks against known ground stations.45
As the aircraft crossed Louisiana toward eastern Texas, the reported signal held or changed relative bearing in a manner the crew interpreted as keeping station with or moving relative to the RB-47 rather than behaving like ordinary ground radar geometry.458
Near the Duncanville, Texas radar-coverage area, Chase contacted the 745th ACWRON site known as Utah, and the 1957 intelligence-summary sequence records visual, ELINT, and ground-radar events in the Dallas-Fort Worth region between approximately 1039Z and 1058Z.456
The strongest internal evidentiary claim in the case file is the 55th Strategic Reconnaissance Wing intelligence judgment that the electronic direction-finding bearings coincided with Chase's visual observations numerous times, indicating that the observed object was the signal source.45
The most cited simultaneity episode occurred during Chase's pursuit and dive near Mineral Wells, Texas, when the visual light, the No. 2 ELINT signal, and Utah ground-radar contact reportedly disappeared together and then reappeared in a new phase of the encounter.456
The northbound return leg kept the case open because the intelligence-summary sequence records the No. 2 direction-finding signal off the aircraft tail until about 1140Z, when the RB-47 was approximately abeam Oklahoma City and the signal faded abruptly.45
Explanation Track
Project Blue Book's final administrative explanation identified the Dallas-Fort Worth observation as an airliner, with McDonald reporting the official file language as an American Airlines Flight 655 identification connected to a separate near-collision near Salt Flats, Texas.345
The University of Colorado Case 5 abstract separately concluded that the described B-47 encounter involved visual light, airborne radar-monitoring receivers, and ground radar, but that the phenomenon remained unidentified because the project could not locate the original records during its investigation.6
The NTIS record for the Colorado project's 1969 report identifies Scientific Study of Unidentified Flying Objects as a U.S. government-sponsored technical report produced under Air Force contract F44620-67-C-0035, placing the Condon material in an official-review chain rather than a private-only commentary stream.9
McDonald's AIAA publication revised the Colorado-era record by stating that he later located case files, corrected the date problem, interviewed crew members, and presented the case as a sample selected by the AIAA UFO Subcommittee for technical review.45
Brad Sparks' later NICAP-hosted update should be treated as subsequent analytical critique rather than original case evidence, but it is useful for flagging disputed compass-heading, Duncanville-radar, and airliner-identification issues that shape modern readings of the Blue Book closure.8
Evidentiary Value and Limits
The case is unusually strong as an evidence-chain document because it combines named military crew, passive ELINT direction finding, cockpit visual observations, ground-radar coordination, ADC reporting, Blue Book administrative closure, and later scientific-review attempts in one recoverable record family.134567
The same file is limited because the strongest surviving public record is a chain of reports, summaries, interviews, and scans rather than original raw scope film, wire recordings, or complete post-flight intelligence exploitation products.456
For this archive, the document's value is not that it proves a final object identity, but that it preserves how an ELINT-centered military case moved from an in-flight multi-sensor event to an official aircraft explanation and then into contested technical reassessment.34568