Threat and Error Management

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Threat and Error Management Normal Operations
Safety Survey The Perspective of ICAO

• Captain Dan Maurino
• Flight Safety and Human Factors ICAO
• Second ICAO Global Symposium on TEM NOSS in ATC
• Washington, DC
• 7 8 February 2007

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Learning from Failure Success
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Capturing the Drift

• Reactive systems
• Accident investigation
• Incident investigation

• Predictive systems
• Electronic safety data acquisition systems
• Direct observation safety data acquisition
  systems

• Proactive systems
• Mandatory reporting systems
• Voluntary self-reporting systems
• Confidential reporting systems

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Safety Data Systems and Levels of Intervention
Safety management levels
Desirable management level
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NOSS TEM Predictive Safety Management

• NOSS Tool How we collect what we look for

• TEM Framework What we look for

• Hazards in operational contexts Threats
• Potential risk (s) Operational Errors
• Result (s) of hazards and risk (s) Undesired
  States

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A Day at the Office

• To achieve companys both safety and production
  goals, air traffic controllers daily must

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Threats
Events or errors that occur beyond the influence
of the ATCO, increase operational complexity, and
which must be managed to maintain the margins of
safety
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Errors
Actions or inactions by the ATCO that lead to
deviations from organizational or ATCO
expectations

• Equipment handling errors incorrect
  interactions with the equipment
• e.g. selecting an inappropriate radar source
  making incorrect inputs to an automated system
• Procedural errors deficiencies in execution
• e.g. wrong separation minima applied leaving the
  position before replacement is ready to take over
• Communication errors deficiencies in the
  exchange of operational information
• e.g. missed calls misinterpretation of a request

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Undesired States
Operational conditions where an unintended
traffic situation results in a reduction of
safety margins

• Aircraft climbing to a wrong altitude
• Aircraft turning in the wrong direction
• Aircraft enters a wrong taxiway
• Aircraft missing a crossing restriction

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TEM A Scenario

• B737 C550 (on non-standard route) on reciprocal
  tracks at FL 310, rate of closure in excess of
  800 knots
• When separated by 22 NM, ATCO (working two
  combined sectors) instructed both crews to alter
  heading and flight level
• Horizontal radar separation standard of 5 NM was
  never infringed
• Short-term conflict alert (STCA) activated
• Vertical separation was established 25 seconds
  prior to the aircraft passing

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TEM Analysis

• Threats
• C550 on non-standard route
• Use of non-standard levels
• ATCO managing two combined sectors

• Errors
• ATCOs timing in recognising a potential conflict

• Undesired State
• From 095655 till 095955 the B737 the C550
  were
• on opposite tracks at FL310 without separation
  provision

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Undesired State Management

• The controller was spending a significant period
  of coordination with another sector controller.
  At 095955, he activated the individual quick
  look function for the flight plan tracks of both
  aircraft. He immediately commenced action to
  ensure a separation standard was maintained. He
  instructed the 737 to expedite descent to FL290
  and instructed the Citation to turn right 30
  degrees. At 100015, he further instructed the
  737 to turn right 20 degrees. He broadcast
  essential traffic information to the 737 about
  the position of the Citation. During that
  transmission, the STCA activated at 100028. At
  100034, the controller told the pilot of the
  Citation to climb to FL320. At 100057, a 2,000
  ft vertical separation standard was established
  when the aircraft were approximately 9 NM apart.

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TEM NOSS ATC SMS Tools