05 Juin 2018

Large decrease in D cases over the last decade

Large decrease in D cases over the last decade: an opportunity to focus on the GEIPAN development over this period.


Statistics on GEIPAN classification (A, B, C, D) can be performed by everyone using the online free-access GEIPAN database. Search in the database can be performed by case, by year (from 1937 to today) or by sighting location. When, despite the consistency and the quality of data and evidences, no explanation of the sighting was possible, cases are classified D by the GEIPAN. They truly are “Unidentified Aerial Phenomena” (UAPs). Up to now, the GEIPAN has chosen to show the different categories in cumulative statistics expressed as percentage of published cases: for the period 1975-2014, the percentage of D cases is around 10% of the total of cases (A, B, C and D) of this period*.

This percentage of D cases, calculated over the last decade, has now dropped to 2%. This decrease has been consolidated  over time and is now understood enough to be highlighted. This progression could be due to 3 factors:

  • 1. A 3-fold increase of investigated and published D cases*
    For the most part, this large increase consists in simple or trivial cases, false contemporary strangeness (Chinese lanterns , photo abnormalities…) and unexploitable cases. It is a pool of cases that anyhow could not be classified D and that were not sent to the GEIPAN before. The real number of cases D would have remained constant meanwhile the percentage of D cases would be mechanically divided by 3.

So, to better describe this progression, the absolute annual number of D cases is becoming more relevant than the percentage. From 1975 to 2004, there was an average of 6.8 cases per year that were classified D. Since 2005, the mean is 2.5 cases/year. The two others factors that contributed to this drop were:

  • 2. A more strict and detailed definition of the D category *
  • 3. More extensive investigations on all reported sightings*

It would be risky to give an opinion on the progression of the celestial “strangeness” only on the basis of the number of cases classified D by the GEIPAN. Indeed, the absolute number of D cases is influenced by some factors defined by the GEIPAN (as described above) and no one fully knows how to evaluate the progression of the proportion of the “very strange” which is never reported to the GEIPAN.


Overall, since 2005 when the actual working objectives were set-up, the GEIPAN is handling an annual flow three times larger than before, whereas the annual rate of unexplained cases (D) dropped by a 2.5 factor. Human resources specifically dedicated to investigations are quite stable. In fact, the GEIPAN has largely improved its investigation methods, first by widely opening them to recent numeric and web-based tools, but also by improving the processing and the analysis of human testimony. Decreasing the average processing time of the cases is, among the current objectives of the GEIPAN, one of the most important one. This will be done by a better and earlier identification of cases with very low “strangeness” level, that will not need to be investigated. This will allow to use the available resources for re-investigating D old cases in order to increase the homogeneity of unexplained cases and to facilitate the scientific exploration of the “unexplained”.



the document below is detailing these different elements



Additional information


STATISTICS ON D CASES: he statistics published on the GEIPAN website concern the overall sighting cases from 1937 up to now.

  • For these statistics, a « consolidated » calculation method was used, which includes only years having an investigation rate of 70% and above. We use here the “dynamic” mode which includes all years, regardless the progress in case processing (see February 2016 news explaining both calculation methods and their low discrepancies).
  • From 01/01/1975 to 12/30/2014, 227 cases were classified D out of 2292 published cases (around 10% of the cases). The mean number of D cases is 6.8 per year.
  • From 01/01/2005 to 12/30/2014, 24 cases were classified D out of 1159 published cases (around 2% of the cases). The mean number of D cases is 2.4 per year.
  • In addition, one can observe that the percentage of explained cases (corresponding to A + B categories) largely increased to 70% versus 40% for the previous decades. 


LARGE INCREASE IN THE NUMBER OF CASES: 3-fold increase, there are more cases in 10 years (1159) than in the previous 30 years (1133).

  • NOTA: in average, 2 or 3 witnesses or testimonies are included in a GEIPAN case. 
    When the OBSERVATION is considered to be banal, a feedback is provided by the GEIPAN to the witnesses without starting an investigation, meaning that only 50% of the sightings will lead to a record, an investigation and a publication as a GEIPAN case. Globally, the number of witnesses having such a feedback from the GEIPAN is 3 times more important than the number of treated and published cases, with feedback to around 500 witnesses per year.

There are several reasons for this huge increase of cases:

  • In march 2007, the GEIPAN database became freely accessible on the GEIPAN website. This open access includes the database of sighting testimonies, the investigation conclusions and, additionally, allows the on-line declaration  of new sighting.  It raises public’s awareness about the GEIPAN and it complements the local “Gendarmerie” network for the collection of testimonies. It fullfills the assignments of the GEIPAN decided in 2005, with objectives of public information and free access to the historical database.
  • The ever-growing capabilities of smartphones and digital cameras that has facilitated the easy access to numeric photographs (no analysis of the photographs will be done anymore by the GEIPAN if the witness has not made a direct visual OBSERVATION of the UAP) (see February 2011 news).
  • The increasing presence in the sky of easily identifiable objects such as chinese lanterns, light balloons or others types of objects used during various celebrations.

Despite the recent UAP identification guide available on-line since september 2011, incomplete or poorly reliable (unclear or too old dates, directions of the sighting too vague, inconsistencies, no possible overlap ...) testimonies are increasing, leading to an increase in C (unexploitable) cases. 



In 2008, the GEIPAN defined or refined 3 main criteria to classify the sighting cases: the strangeness level, the considered probability of each possible hypothesis  and the consistency. These criteria improved the definition of the different categories and allowed to divide the D category in 2 distinct parts: D1 and D2. 

  • classified UAPs: sighting that is fully explained without any doubt

  • B classified UAP: GEIPAN hypothesis for this sighting being considered very probable

  • C classified UAP: full analysis of the sighting not performed due to the lack of information

  • D classified UAP: unexplained sighting despite the available information. The D category can be divided in 2 categories:

    • D1: UAPs corresponding to strange phenomena with a moderate consistency; for example, case with a single testimony, without any photographic or video evidences

    • D2: UAPs corresponding to very strange phenomena with a strong consistency; several independent testimonies of the same phenomenon and/or photographic or video evidences and/or marks on the ground.  

The main goal is to obtain a more objective and more transparent classification that reflects as much as possible the real knowledge about the case obtained at the end of the investigations (see “UAP classification procedure” in news of December 10th, 2008). Except for A cases, the classification cannot be considered definitive as long as the real explanation, whatever it is, has not been identified and validated. Therefore, D1 and D2 cases can switch to another category at all time, as function of additional information, evidences or new investigations.




Since 2008 and with more extensive investigations, the GEIPAN classification has moved to A/B/C/D1/D2. By a specific standardized questionnaire, the GEIPAN website allows to collect all possible details of each testimony. This questionnaire can complement the “Gendarmerie” (i.e. police ) official proceedings. Remote investigations are then conducted and if necessary, completed by a “field” investigation including a meeting with the witness (in 10% of the cases). The use of numeric and web-based tools has deeply changed the investigation process, especially in the initial and remote step. Unexplained cases are classified D1 or D2 according to their strangeness level and their consistency. For these, a field investigation (for a reconstitution of the sighting) and a cognitive interview of the eyewitness are systematically performed. The cognitive interview allows to increase the gathered information by putting the witness back in the context of its sighting. The D1 and D2 cases are always published with their investigation report. Investigations of the most complex cases can be long, often lasting more than a year. Final conclusions on these particular investigations are approved by a group of experts.


Previously and because of the limited tools available, it was not easy to extend the investigations beyond those performed by the local “Gendarmerie”. So, for most of the cases (D included), the “Gendarmerie” proceedings were the main evidences used (and published) by the GEIPAN to study and classify the case. Nevertheless, extensive field investigations were conducted for the oddest cases before any classification and reports or technical notes are available on those cases. Simultaneously to the processing of new cases, new investigations on old D cases are conducted by the GEIPAN (around 20 cases were reanalysed and 100 cases are in progress, among them some very old like those of 1954, see news “progress in publication of cases from 1954”).