THE DOCUMENT
(Unchanged: two documents from PURSUE Release 01. DOW-UAP-D48, a Research Triangle Institute final report titled “Modeling Unlikely Space-Booster Failures in Risk Calculations”, prepared for the US Air Force and dated September 1996. DOW-UAP-D49, the “Vandenberg AFB Launch Summary 1958 to 2000”, compiled by the 30th Space Wing Office of History. Both published by the U.S. Department of War at war.gov/ufo.)
Why this one is worth your time
Every document briefed in this series so far has been, in some sense, about an unidentified object. These two are not. D48 and D49 are not UAP encounter reports. They contain no sightings, no aircrew descriptions, no sensor footage. D48 is a technical risk-analysis study about how rockets fail. D49 is an administrative register of rocket launches. They were both, however, placed inside an official UAP release: a release that, alongside its encounter reports, carries substantial material describing entirely conventional aerospace activity, the kind of material that helps explain some sightings away. This briefing is about what each document is, and where it sits in the release.
What the documents say
Both files are authentic and official, and neither contains any UAP content. Here is what each one is.
DOW-UAP-D48, the booster-failure study. D48 is a 1996 final report from the Research Triangle Institute, an established American research organisation, prepared under contract for the US Air Force, specifically the safety offices of the 30th Space Wing at Vandenberg and the 45th Space Wing at Patrick. Its title is “Modeling Unlikely Space-Booster Failures in Risk Calculations.” The subject is narrow and technical. When a launch vehicle fails catastrophically, most of its debris falls close to the intended flight path. The report’s own introduction lists the usual causes: “premature thrust termination, stage ignition failure, tank rupture or explosion, or rapid out-of-control tumble.” But the report is interested in a rarer outcome. It calls these “Mode-5 failure responses”: cases where a malfunction causes the vehicle “to execute a sustained turn away from the flight line”, for example “control failures that cause the rocket engine to lock in a fixed position”, or “erroneous orientation of the guidance platform.” A booster failing in this way does not just fall straight down. It can fly a curving path well off course before it breaks up or impacts.
The report builds a mathematical model for where the debris from such failures would land, inside a risk-analysis program the report calls DAMP, and tunes the model against simulated and real failure data. Its appendices contain “a listing and brief narrative failure history of the Atlas, Delta, and Titan missile and space-vehicle launches” from the beginning of each programme through August 1996, classifying each flight by how, if at all, it went wrong. A document like this is a catalogue of the ways a rocket can behave abnormally in the sky: turning, tumbling, breaking up, scattering burning debris on an unexpected path. Those behaviours, seen from the ground or from a cockpit by someone who does not know a launch failure is underway, are the kind of thing that gets reported as a strange, manoeuvring, fragmenting object.
It is worth being precise about what D48 is not. It is not a UAP study. It does not mention unidentified phenomena. It is an engineering risk document, and the description that it points toward conventional explanations is an inference about why it was included, not a claim the document makes about itself.
DOW-UAP-D49, the Vandenberg launch summary. D49 is even plainer. It is the “Vandenberg AFB Launch Summary 1958 to 2000”, compiled by the 30th Space Wing History Office. Its own foreword describes it as “the official registry of all major launch operations conducted from Vandenberg Air Force Base, California”, presented “in chronological order beginning with the first launch on 16 December 1958.” The bulk of the document is exactly that: a launch-by-launch table, running to well over a thousand numbered entries, each giving a date, a nickname, a launch facility, a vehicle type, a programme and a running count. Thor, Atlas, Titan, Minuteman, Delta, Pegasus, Scout, Peacekeeper. It includes summary matrices of launches by year and by command, a glossary of acronyms, and a guide to the launch facilities themselves.
Like D48, D49 contains no UAP content of any kind. It is a historical and administrative record. Vandenberg sits on the California coast and launches south over the Pacific, and its rockets and their re-entering or de-orbiting hardware have, for decades, been a documented and recurring source of “strange lights” reports along the western United States. A complete, dated register of every launch from a major spaceport is a tool: given a sighting date and location, a launch can be checked as a possible account of it. D49 belongs in the same category as D48. It is not a sighting; it is reference material.
What the documents do not say
Anything about UAP directly. D48 and D49 contain no sightings and no anomalies, and nothing in them is evidence either for or against the phenomenon.
That booster failures or rocket launches explain any specific case in the rest of the release. These documents are general reference material. Applying them to an individual sighting would require matching dates, locations and trajectories, which is a separate exercise.
The intent behind including these two files. The documents do not state their own purpose. That they were included as candidate conventional-explanation material is the reading that matches how the project’s own inventory work characterised them, but the files themselves do not say so. What the files do say, plainly, is that the release contains substantial, official, non-anomalous reference material.
From the record
“Premature thrust termination, stage ignition failure, tank rupture or explosion, or rapid out-of-control tumble.” D48, listing the usual causes of catastrophic launch failure
“To execute a sustained turn away from the flight line.” D48, describing a “Mode-5 failure response”
“A listing and brief narrative failure history of the Atlas, Delta, and Titan missile and space-vehicle launches.” D48, describing its own appendices
“The official registry of all major launch operations conducted from Vandenberg Air Force Base, California.” D49, foreword, describing itself
Where the case connects
This is the same broad-archive question Briefing 1 set out, and it sits alongside the deliberately sceptical NASA briefing (Briefing 8) as another instance of the release carrying its own conventional material. Read next to the encounter reports elsewhere in the release, D48 and D49 are the part of the file that describes how rockets fail and a complete record of when they launched.
The files leave one loose end stated as a neutral fact. We do not know with certainty why these two specific files were placed in the release. The documents do not state their own purpose, and the inventory characterisation is the project’s reading rather than the documents’ own words. Any later note that records the selection rationale would land in this series when it does.
Read it yourself
DOW-UAP-D48 and DOW-UAP-D49 are hosted at war.gov in PURSUE Release 01.
Read the file. Decide for yourself.
References and further reading
- DOW-UAP-D48, Research Triangle Institute, “Modeling Unlikely Space-Booster Failures in Risk Calculations”, final report for the US Air Force, September 1996, hosted at war.gov
- DOW-UAP-D49, “Vandenberg AFB Launch Summary 1958 to 2000”, 30th Space Wing Office of History, hosted at war.gov
- Presidential Unsealing and Reporting System for UAP Encounters, U.S. Department of War, war.gov/ufo
- AARO UAP Records, All-domain Anomaly Resolution Office, aaro.mil/UAP-Records
- Briefing 1 in this series, on how to read PURSUE Release 01 and the evidence-tier system
- Briefing 8 in this series, the deliberately sceptical NASA briefing, on the same honest-framing principle