COLUMBIA ACCIDENT INVESTIGATION BOARD REPORT

Volume I

August 2003

EXECUTIVE SUMMARY

The Columbia Accident Investigation Board's independent investigation into the February 1, 2003, 

loss of the Space Shuttle Columbia and its seven-member crew lasted nearly seven months. A staff 

of more than 120, along with some 400 NASA engineers, supported the Board's 13 members. 

Investigators examined more than 30,000 documents, conducted more than 200 formal interviews, 

heard testimony from dozens of expert witnesses, and reviewed more than 3,000 inputs from the 

general public. In addition, more than 25,000 searchers combed vast stretches of the Western 

United States to retrieve the spacecraft's debris. In the process, Columbia's tragedy was 

compounded when two debris searchers with the U.S. Forest Service perished in a helicopter 

accident.

The Board recognized early on that the accident was probably not an anomalous, random event, but 

rather likely root-ed to some degree in NASA's history and the human space flight program's 

culture. Accordingly, the Board broadened its mandate at the outset to include an investigation of a 

wide range of historical and organizational issues, including political and budgetary considerations, 

compromises, and changing priorities over the life of the Space Shuttle Program. The Board's 

conviction regarding the importance of these factors strengthened as the investigation progressed, 

with the result that this report, in its findings, conclusions, and recommendations, places as much 

weight on these causal factors as on the more easily understood and corrected physical cause of the 

accident.

The physical cause of the loss of Columbia and its crew was a breach in the Thermal Protection 

System on the leading edge of the left wing, caused by a piece of insulating foam which separated 

from the left bipod ramp section of the External Tank at 81.7 seconds after launch, and struck the 

wing in the vicinity of the lower half of Reinforced Carbon-Carbon panel number 8. During re-entry 

this breach in the Thermal Protection System allowed superheated air to penetrate through the 

leading edge insulation and progressively melt the aluminum structure of the left wing, resulting in 

a weakening of the structure until increasing aerodynamic forces caused loss of control, failure of 

the wing, and break-up of the Orbiter. This breakup occurred in a flight regime in which, given the 

current design of the Orbiter, there was no possibility for the crew to survive.

The organizational causes of this accident are rooted in the Space Shuttle Program's history and 

culture, including the original compromises that were required to gain approval for the Shuttle, 

subsequent years of resource constraints, fluctuating priorities, schedule pressures, 

mischaracterization of the Shuttle as operational rather than developmental, and lack of an agreed 

national vision for human space flight. Cultural traits and organizational practices detrimental to 

safety were allowed to develop, including: reliance on past success as a substitute for sound 

engineering practices (such as testing to understand why systems were not performing in 

accordance with requirements); organizational barriers that prevented effective communication of 

critical safety information and stifled professional differences of opinion; lack of integrated 

management across program elements; and the evolution of an informal chain of command and 

decision-making processes that operated outside the organization's rules.
This report discusses the attributes of an organization that could more safely and reliably operate 

the inherently risky Space Shuttle, but does not provide a detailed organizational prescription. 

Among those attributes are: a robust and in-dependent program technical authority that has 

complete control over specifications and requirements, and waivers to them; an independent safety 

assurance organization with line authority over all levels of safety oversight; and an organizational 

culture that reflects the best characteristics of a learning organization.

This report concludes with recommendations, some of which are specifically identified and 

prefaced as "before return to flight." These recommendations are largely related to the physical 

cause of the accident, and include preventing the loss of foam, improved imaging of the Space 

Shuttle stack from liftoff through separation of the External Tank, and on-orbit inspection and 

repair of the Thermal Protection System. The remaining recommendations, for the most part, stem 

from the Board's findings on organizational cause factors. While they are not "before return to 

flight" recommendations, they can be viewed as "continuing to fly" recommendations, as they 

capture the Board's thinking on what changes are necessary to operate the Shuttle and future 

spacecraft safely in the mid- to long-term.

These recommendations reflect both the Board's strong support for return to flight at the earliest 

date consistent with the overriding objective of safety, and the Board's conviction that operation of 

the Space Shuttle, and all human space-flight, is a developmental activity with high inherent