nevels columbia challenger

7/30/2019 Nevels Columbia Challenger

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Fundamental CanonsEngineers, in theperformance of their duties, shall:

1. Hold paramount the safety, health and

welfare of the public....2. Perform services only in the areas of

their competence.

3. Issue public statements only in anobjective and truthful manner.

NSPE Code of Ethics for Engineers


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NSPE Code of Ethics for Engineers

NSPE Canons continued

4. Actfor each employer or client as faithfulagents or trustees.

5. Avoid deceptive acts in the solicitation ofprofessional employment.

6. Conduct themselves honorably, responsibly,ethically, and lawfully so as to enhance the

honor, reputation and usefulness of theprofession.


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The loss of theChal lenger

28 Jan. 198673 sec after liftoffaltitude>35,000 ftairspeed>Mach 1.5
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failure in the joint

between the two lowersegments of the right SolidRocket Motor.

The specific failure wasthe destruction of theseals that are intended toprevent hot gasses fromleaking through the joint

during the propellant burnof the rocket motor.

(Rogers Commission Report)

Challenger - The Physical Cause


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Challenger

Liquid hydrogen tank explodes, ruptures liquidoxygen tank

Resulting massive explosion destroys the shuttle


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The Challenger Investigation

The Rogers Commission,whichinvestigated the incident, determined:

The SBR joint failed when jet flames

burned through the o-rings in the joint

NASA had long know about recurrentdamage to the o-rings

Increasing levels of o-ring damage hadbeen tolerated over time

Tolerated based on the rational thatnothing bad had happened yet


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The Investigation continued

The Commission also determined that:

SRB experts had expressed concerns about thesafety of the Challenger launch

NASAs culture prevented these concerns from

reaching top decision-makers Past successes had created an environment of

over-confidence within NASA

Extreme pressures to maintain launch schedulesmay have prompted flawed decision-making


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FEB 1, 2003 8:59 EST

All 7 astronauts are killed

$4 billion spacecraft isdestroyed

Debris scattered over2000 sq-miles of Texas

NASA grounds shuttlefleet for 2-1/2 years

Space shuttle Columbia,re-entering Earthsatmosphere at 10,000mph, disintegrates


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Insulating foam separatesfrom external tank 21seconds after lift-off

Foam strikes underside

of left wing, breachesthermal protectionsystem tiles.

Superheated air enters

wing during re-entry,melting aluminum struts

Aerodynamic stressesdestroy weakened wing

Columbia - The Physical Cause


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Columbia Investigation

Foam strike detected inlaunch videos on Day 2

Engineers requestedinspection by crew or

remote photo imageryto check for damage

Mission managersdiscounted foam strikesignificance

No actions were taken toconfirm shuttle integrity orprepare contingency plans


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Columbia- The Organizational Causes

In our view, the NASA organizational

culture had as much to do with thisaccident as the foam.

CAI B Report, Vol. 1, p. 97

NASA had received painfullessons about its culture fromthe Challenger incident

Columbia AccidentInvestigation Board (CAIB)

found disturbing parallelsremaining at the time of theColumbia incident


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Challenger

1.Why did NASAcontinue to fly withknown O-ring

erosion problems inthe years before theaccident?

2. Why did NASAmanagers on the eveof the launch decide

that launching themission in such coldtemperatures was anacceptable risk,despite the concernsof their engineers?

Columbia

1.Why did NASAcontinue to fly withknown foam

shedding/impactproblems in the yearsproceeding theaccident?

2. Why did themanagers concludethe observed foamstrike 81.9 secondsinto flight was not athreat to the mission,despite concerns ofengineers?

Similarities in the Challengerand Columbiacases


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Be wary of incrementally increasing risks bynorm al izat ion o f deviance.

Learn to differentiate between Proper EngineeringDecisions (PED) and Proper Management Decisions(PMD)

Engineering processes (the decision-makingprocess to arrive at the launch decision) needcontinuous review.

Be watchful for indications of group-think Learn to recognize when external pressures or

conflicting interests (profits, prestige,) causedeviations from usual engineering processes.

Lessons


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Columbia near-misses were regarded as successes of a robustsystemrather thannear-failures. No disasters had resulted fromprior foam strikes, so strikes were no longer a safety-of-flight issueChallenger parallel failure of the primary o-ring demonstrated the

adequacy of the secondary o-ring to seal the joint

Throughout the Columbia risk assessment process, NASA 6 person

Shuttle Program Management Boardwere influenced by their belief

that nothing could be done even if damage was detected. This affectedtheir stance on investigation urgency, thoroughness and possible

contingency actions.

Risk Assessment


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The shuttle management board Chair squelched requests for external

photos to be taken after the requests had been sent by two individual

departments at NASA.... Ref. Comm Check by William Harwood and

Michael Cabbage

Based on computer modeling later proven inadequate, the boards

mistakenbelief was that the damage was not serious

The computer model was an essential part of the decision not to act!!!

Risk management

Flight risk managementFlight risk management


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Power Point Deception

Edward A Tuttle, Power Pointdoes Rocket Science


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Normalization of deviance

The acceptance of events that are notexpected to happen has been described

by soc iologis t Diane Vaughan as thenormalization of deviance.

Flight risk management


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After 113 shuttle missions, foam shedding, debris impacts, and TPS tiledamage came to be regarded as only a routine maintenance concern

Startingtwo days after the Columbia launch, after reviewing filmdetecting the foam impact on the left wing, NASA

Engineering made three separate requests for Department ofDefense imaging of the shuttle in orbit to more preciselydetermine damage. The capability existed for imaging ofsufficient resolution to provide meaningful examination.

The shuttle program managers declined the engineers' request toimage the shuttle's wing before reentry.

g g

Deviance and Response


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Maintaining a Sense of Vulnerability

Near-misses were regarded as successes of a robustsystem rather than near-failures

No disasters had resulted from prior foam strikes,so strikes were no longer a safety-of-flight issue

Challenger parallel failure of the primary o-ringdemonstrated the adequacy of the secondary o-ringto seal the joint

A weak sense of vulnerability can lead to taking future

success for granted and to taking greater risks



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Power Point Deception

Edward A Tuttle, Power Pointdoes Rocket Science


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While the shuttle was in flight former Flight Director Wayne Hale

worked outside of proper NASA channels in an effort to get DoD

imaging of the damage, even though the board Chairoverruled his

request.

In the aftermath

Hale was promoted to Space Shuttle

ProgramManager and then on to NASAHeadquarters.

After the Columbia Investigation


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Combating Normalization of Deviance

This history portrays an incrementaldescent into poor judgment.

Diane Vaughan,

The Challenger Launch Decision

Each successful mission reinforced the perception thatfoam shedding was unavoidableeither unlikely tojeopardize safety or an acceptable risk

Foam shedding, which violated the shuttle design basis,

had been normalized

Challenger parallel tolerance of damage to the primaryo-ring led to tolerance of failure of the primary o-ring which led to the tolerance of damage to the

secondary o-ring which led to disaster


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Ensure Open and Frank Communications

I must emphasize (again) that severe enough

damage could present potentially grave hazardsRemember the NASA safety posters everywhere

around stating, If its not safe, say so? Yes, its that

serious.

Memo that was composed but never sent

Management adopted a uniform mindset that foamstrikes were not a concern and was not open tocontrary opinions.

The organizational culture Did not encourage bad news Encouraged 100% consensus Emphasized only chain of command communications Allowed rank and status to trump expertise


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An Epilog

During launch, a large piece of foam separated from theexternal fuel tank, but fortunately did not strike theshuttle, which landed safely 14 days later

The shuttle fleet was once again grounded, pendingresolution of the problem with the external fuel tankinsulating foam

nevels columbia challenger

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