CORROBORATED
CF-GEI-20080401844 CORROBORATED
The Bailly Thunder Incident
CASE FILE — CF-GEI-20080401844 — CASEFILES CLASSIFIED ARCHIVE
Date Date when the incident was reported or occurred
2008-04-28
Location Reported location of the sighting or event
Bailly, Yvelines, France
Duration Estimated duration of the observed phenomenon
5-6 seconds
Object Type Classification of the observed object based on witness descriptions
unknown
Source Origin database or archive this case was sourced from
geipan
Witnesses Number of known witnesses who reported the event
1
Country Country where the incident took place
FR
AI Confidence AI-generated credibility score based on source reliability, detail consistency, and corroboration
85%
On April 28, 2008, at approximately 4:10 AM, a single witness in Bailly (Yvelines department, Île-de-France region) reported hearing a significant acoustic phenomenon over their residence. The witness described hearing a deep, rolling sound originating from the northeast direction. This sound transformed into what they perceived as a thunderclap that persisted for 5-6 seconds as it passed directly overhead, causing fear and alarm to the witness. The sound subsequently moved away toward the southwest direction.
The witness reported this incident to GEIPAN (Groupe d'études et d'informations sur les phénomènes aérospatiaux non identifiés), France's official UFO/UAP investigation body operated by CNES (Centre National d'Études Spatiales). GEIPAN conducted a standard investigation, cross-referencing the witness account with meteorological data from the region for that date and time period.
The investigation revealed that significant thunderstorm activity was recorded in the residential area on the date in question. GEIPAN concluded with high confidence that the witness had experienced a thunderclap from a violent storm, leading to a Classification A designation—the highest level of certainty indicating a conclusively identified phenomenon with no anomalous characteristics remaining.
02 Timeline of Events
04:10
Initial Acoustic Detection
Witness hears a deep, rolling sound ("bruit sourd et roulant") originating from the northeast direction, likely awakening them from sleep.
04:10:02
Sound Intensification
The rolling sound transforms into what the witness identifies as a thunderclap ("coup de tonnerre") as it approaches the residence.
04:10:03-04:10:08
Peak Acoustic Event Overhead
Thunder sound persists for 5-6 seconds directly over the habitation, causing fear to the witness ("effrayant le témoin"). Peak intensity of the acoustic phenomenon.
04:10:09
Sound Recession
The thunderclap sound moves away toward the southwest direction, diminishing in intensity.
2008-04-28 (Date)
GEIPAN Investigation Initiated
Witness reports the incident to GEIPAN. Investigation team cross-references meteorological data for the Bailly region on April 28, 2008.
Post-Investigation
Classification A Assigned
GEIPAN confirms significant thunderstorm activity in the region on the date in question. Case conclusively identified as thunder from a violent storm. Classification A (explained with certainty) assigned.
03 Key Witnesses
Anonymous Witness
Civilian resident
medium
Resident of Bailly, Yvelines who reported an alarming sound phenomenon to authorities. No background information available beyond residential location.
"A deep, rolling sound coming from the northeast that transformed into a thunderclap that lasted 5-6 seconds as it passed over the residence, moving toward the southwest."
04 Analyst Notes -- AI Processed
This case represents a straightforward meteorological identification and demonstrates GEIPAN's thorough investigative methodology, even for mundane reports. The witness's description of a "deep, rolling sound" that "transformed into a thunderclap" is textbook acoustic signature of thunder, particularly the rolling quality caused by sound waves bouncing off terrain and atmospheric layers. The directional movement from northeast to southwest aligns with typical storm cell progression patterns in the Île-de-France region.
The witness's fear response, while understandable given the early morning hour (4:10 AM) and the intensity of the sound, does not indicate any anomalous phenomena. Thunder occurring directly overhead can indeed be startling, particularly during sleep hours when cognitive processing is impaired. The 5-6 second duration is consistent with close-proximity lightning strikes where the acoustic signature extends as sound waves reflect and refract through the atmosphere. GEIPAN's access to meteorological records confirming "significant thunderstorm activity" provides definitive corroboration. The Classification A designation is entirely appropriate, indicating zero ambiguity in the explanation.
05 Theory Comparison
BELIEVER ANALYSIS
SKEPTIC ANALYSIS
Misidentified Natural Phenomenon Under Sleep Disruption
The witness, awakened suddenly at 4:10 AM, experienced a common meteorological event but reported it due to disorientation and fear. Thunder occurring directly overhead can be particularly startling when one is in a state of sleep inertia. The 5-6 second duration and directional movement are textbook thunder characteristics. No anomalous elements present—this represents normal human response to an intense but mundane natural event experienced under sub-optimal cognitive conditions.
06 Verdict
ANALYST VERDICT
This case is definitively explained as a natural meteorological phenomenon—a thunderclap from a violent storm. The witness credibility is not in question; they accurately reported what they experienced, but misinterpreted or were uncertain about a common atmospheric event, possibly due to the disorienting effects of being awakened at 4:10 AM. GEIPAN's investigation was appropriately brief, as meteorological data immediately confirmed storm activity. This case holds no significance for UAP research but serves as a useful example of how terrestrial phenomena can be alarming when experienced under certain conditions. The case demonstrates the value of systematic investigation and meteorological cross-referencing in eliminating non-anomalous reports from the UAP dataset.
AI CONFIDENCE SCORE:
85%
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