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Why GEIPAN Separates Quality From Strangeness

GEIPAN shows how separating observation quality from residual strangeness can make UFO case labels easier to judge.

On this page

  • How GEIPAN categories work
  • Why consistency and strangeness are separate tests
  • What other databases can borrow from the model
Preview for Why GEIPAN Separates Quality From Strangeness

Introduction

When comparing the reliability of UFO/UAP databases, one of the key challenges is distinguishing between how good the data is and how strange or unexplained a case remains after investigation. France’s official investigative body, the GEIPAN (Groupe d’Études et d’Informations sur les Phénomènes Aérospatiaux Non‑identifiés), offers a well‑documented classification model that illustrates this distinction in practice. Because its methodology is public and reproducible, GEIPAN’s approach is frequently cited as an example of how to separate observation quality (data reliability) from residual unexplained content (strangeness) in UFO reporting systems — a valuable lens for judging and comparing database reliability. [geipan.fr]geipan.frClassification | GEIPANClassification | GEIPAN

GEIPAN Model illustration 1

How GEIPAN Categories Work

At the heart of GEIPAN’s reliability model are two independent criteria used to classify every case: residual strangeness (E) and data consistency (C). After a report is collected and analysed, these metrics determine its final category. [geipan.fr]geipan.frMission & Geipan | GEIPANMission & Geipan | GEIPAN

Residual Strangeness (E)

This is a quantitative measure of how much of the reported phenomenon cannot be explained by known physical or perceptual hypotheses. Investigators generate and assess possible explanations grounded in current scientific knowledge — such as astronomical objects, atmospheric phenomena or known human‑made artefacts — and then evaluate how much of the witness’s description remains strange after this comparison. A higher E score indicates more unexplained content. [geipan.fr]geipan.frMission & Geipan | GEIPANMission & Geipan | GEIPAN

Data Consistency (C)

This metric reflects the quality and reliability of the information collected — the number of independent witnesses, the precision of their responses, the presence of supporting evidence such as photographs or radar, and the overall coherence of the account. GEIPAN uses a specific weighting scheme to quantify this. [geipan.fr]geipan.frL E GEIPAN: « LE BUREAU DES OVNIS » OU DES PAN?| GEIPANJune 28, 2021 — Date de publication 28 juin 2021 LE GEIPAN: « LE BUREAU DES OVNIS » OU DES PAN? Date de publication 28 juin 202…Published: June 28, 2021

These two dimensions are deliberately evaluated separately: a sighting can be highly strange but poorly supported by reliable data, or strongly consistent yet easily explained. The categories that GEIPAN assigns emerge from the interplay between these axes. [geipan.fr]geipan.frMethodology | GEIPANFAQ GEIPAN 1What is GEIPAN? * GEIPAN (Group for the Study and Information of Unidentified Aerial/Aerospace Phenomena) is a technical department of th…

70 Years of UFO-UAP Data: A Scientific Review with Robert Powell (SCU Founder)

Channel: QOOSP Lab: multidisciplinary research & dialogue · Views: 649 · Uploaded: October 2025 · Length: 1 hour 25 minutes

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Why Consistency and Strangeness Are Separate Tests

One of the strengths of GEIPAN’s model from a reliability standpoint is its conceptual separation of “can we reasonably explain this sighting?” from “how good and reliable is the evidence?”. This separation has practical implications:

  • Quality isn’t confused with mystery. A bizarre report with minimal corroborating evidence doesn’t automatically become an unexplained case; it often falls into category C (insufficient data). [geipan.fr]geipan.frUNE MÉTHODOLOGIE DE CLASSIFICATION CONSOLIDÉE SUR DES DÉCENNIES La classification du GEIPAN (A/B/C/D*) a été…
  • Strangeness alone doesn’t inflate confidence. GEIPAN requires not just high residual strangeness but also high consistency before a case is categorised as genuinely unexplained. [geipan.fr]geipan.fr1977 within the CNES: * Provides a public and official feedback to all people’s “liv…
  • Routine re‑evaluation is built in. Because both metrics are based on evidence and hypotheses, cases — especially those initially unresolved — can be revisited as new data or analysis methods become available. [geipan.fr]geipan.frdentifiés) consiste à fournir un service opérationnel basé sur des enquêtes liées aux…

In practice, GEIPAN’s categories work like this:

  • Category A: Explained with high confidence — both low strangeness and adequate consistency. [geipan.fr]geipan.frClassification | GEIPANClassification | GEIPAN
  • Category B: Probably explained — plausible hypotheses but some uncertainties remain. [geipan.fr]geipan.frMission & Geipan | GEIPANMission & Geipan | GEIPAN
  • Category C: Unresolved due to insufficient or unreliable data, regardless of strangeness. [geipan.fr]geipan.frMission & Geipan | GEIPANMission & Geipan | GEIPAN
  • Category D: Unexplained after full investigation — where strangeness is significant and data consistency is strong. Subdivisions (D1 and D2) can reflect middling versus strong consistency among unexplained cases. [geipan.fr]geipan.frL E GEIPAN: « LE BUREAU DES OVNIS » OU DES PAN?| GEIPANJune 28, 2021 — Date de publication 28 juin 2021 LE GEIPAN: « LE BUREAU DES OVNIS » OU DES PAN? Date de publication 28 juin 202…Published: June 28, 2021

This dual‑axis logic turns classification into a reliability model, where the evidential weight is explicit rather than implicit.

France's Official UFO Investigation Agency (GEIPAN)

Channel: Kryptoscipher · Views: 108 · Uploaded: February 2025 · Length: 10 minutes

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GEIPAN Model illustration 3

GEIPAN Model illustration 2

What Other Databases Can Borrow from the Model

GEIPAN’s approach offers several lessons for other UFO/UAP databases that aim to be reliable reference sources rather than simple crowd‑sourced collections:

  • Explicit criteria reduce ambiguity. Separating observational quality from unexplained content helps users understand why a case is considered identified, unresolved, or unexplained.
  • Quantifiable measures aid comparability. By modelling metrics like strangeness and consistency on numeric scales, GEIPAN makes classification less subjective, or at least more traceable.
  • Documentation supports external evaluation. Because GEIPAN publishes its methodology and many of its investigation outcomes, third‑party analysts can assess how categories are reached — a key aspect of database reliability.
  • Re‑evaluation mechanisms bolster quality over time. Systems that allow for revisiting uncertain cases as new evidence comes in help ensure that databases remain accurate and up‑to‑date.

In the broader landscape of UFO report catalogues, GEIPAN’s method stands out because it makes the reliability model itself visible rather than leaving users to infer it from opaque labels or aggregated totals. This transparency helps researchers, journalists and the public differentiate between high‑confidence explanations, data limitations, and genuinely unresolved phenomena, which in turn supports more grounded comparisons across international databases. [geipan.fr]geipan.frMethodology | GEIPANFAQ GEIPAN 1What is GEIPAN? * GEIPAN (Group for the Study and Information of Unidentified Aerial/Aerospace Phenomena) is a technical department of th…

CNES's UFO Archive!

Channel: Science Of Space · Views: 164 · Uploaded: July 2021 · Length: 2 minutes 24 seconds

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Endnotes

  1. Source: geipan.fr
    Title: Classification | GEIPAN
    Link: https://www.geipan.fr/en/node/58787

  2. Source: geipan.fr
    Title: Mission & Geipan | GEIPAN
    Link: https://geipan.fr/missions-methodes-et-resultats

  3. Source: geipan.fr
    Title: Mission & Geipan | GEIPAN
    Link: https://www.geipan.fr/en/node/58792

  4. Source: geipan.fr
    Title: L E GEIPAN: « LE BUREAU DES OVNIS » OU DES PAN?
    Link: https://geipan.fr/fr/node/58703
    Source snippet

    | GEIPANJune 28, 2021 — Date de publication 28 juin 2021 LE GEIPAN: « LE BUREAU DES OVNIS » OU DES PAN? Date de publication 28 juin 202...

    Published: June 28, 2021

  5. Source: geipan.fr
    Title: Methodology | GEIPANFAQ GEIPAN 1
    Link: https://www.geipan.fr/en/node/58788
    Source snippet

    What is GEIPAN? * GEIPAN (Group for the Study and Information of Unidentified Aerial/Aerospace Phenomena) is a technical department of th...

  6. Source: geipan.fr
    Link: https://geipan.fr/fr/node/58787
    Source snippet

    UNE MÉTHODOLOGIE DE CLASSIFICATION CONSOLIDÉE SUR DES DÉCENNIES La classification du GEIPAN (A/B/C/D*) a été...

  7. Source: geipan.fr
    Link: https://www.geipan.fr/en/node/440
    Source snippet

    1977 within the CNES: * Provides a public and official feedback to all people’s “liv...

  8. Source: geipan.fr
    Link: https://www.geipan.fr/index.php/fr/node/58792
    Source snippet

    dentifiés) consiste à fournir un service opérationnel basé sur des enquêtes liées aux...

  9. Source: cnes-geipan.fr
    Title: Geipan How does GEIPAN classify observation cases? | GEIPAN
    Link: https://www.cnes-geipan.fr/en/node/412
    Source snippet

    | GEIPANThe classification process is done according a quantitative and qualitative assessment of two parameters: the consistency (C) of...

  10. Source: cnes-geipan.fr
    Link: https://www.cnes-geipan.fr/en/node/58787
    Source snippet

    [Select] [Input] [Input] [Input] Sommaire 1. A classification methodology consolidated over decades 2. St...

  11. Source: cnes-geipan.fr
    Link: https://cnes-geipan.fr/en/node/58788
    Source snippet

    The most difficult phenomenon to explain...

Additional References

  1. Source: cnes-geipan.fr
    Title: Mission & Geipan | GEIPANSommaire 1
    Link: https://www.cnes-geipan.fr/fr/missions-methodes-et-resultats
    Source snippet

    40 ans de GEIPAN, c'est d'abord 40 ans d'émotions dans le ciel 2. L’étrangeté moderne dans le ciel s’appelle Soucoupe ou OVNI depuis 1947...

  2. Source: cnes-geipan.fr
    Title: It is based on 2 main crite
    Link: https://www.cnes-geipan.fr/en/missions-methodes-et-resultats
    Source snippet

    Mission & Geipan | GEIPANA CLASSIFICATION METHODOLOGY CONSOLIDATED OVER DECADES Image: Consistance Cas Geipan Since 2008, a more detailed...

  3. Source: youtube.com
    Title: 70 Years of UFO-UAP Data: A Scientific Review with Robert Powell (SCU Founder)
    Link: http://www.youtube.com/watch?v=0hS4OYk_rOU
    Source snippet

    I Analyzed 173,747 UFO Reports… Here’s What I Found...

  4. Source: youtube.com
    Title: CNES’s UFO Archive!
    Link: http://www.youtube.com/watch?v=jdN-BBirSA8
    Source snippet

    GEIPAN UAP UFO investigation classification GEIPAN: Everything You Need to Know About UFOs and Aerial Phenomena Science And Life...

  5. Source: youtube.com
    Title: France’s Official UFO Investigation Agency (GEIPAN)
    Link: http://www.youtube.com/watch?v=lXi5B0NTwVc
    Source snippet

    70 Years of UFO-UAP Data: A Scientific Review with Robert Powell (SCU Founder)...

  6. Source: youtube.com
    Title: GEIPAN: Everything You Need to Know About UFOs and Aerial Phenomena
    Link: http://www.youtube.com/watch?v=K-dgmfIOYBE
    Source snippet

    France's Official UFO Investigation Agency (GEIPAN)...

  7. Source: cnes-geipan.fr
    Link: https://www.cnes-geipan.fr/fr/node/25
    Source snippet

    La méthodologie de classification au GEIPAN | GEIPANFebruary 26, 2021 — Date de publication 26 Février 2021 LA MÉTHODOLOGIE DE CLASSIFICA...

    Published: February 26, 2021

  8. Source: youtube.com
    Title: I Analyzed 173,747 UFO Reports… Here’s What I Found
    Link: http://www.youtube.com/watch?v=dnQU6Rj1fD8
    Source snippet

    CNES's UFO Archive...

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