Critical Decision Method Case Study: B747 Disclaimer: Knowledge, Skills & Ability must known to the SME correct as at 17 Jul 08

Sweep 1: Identifying and selecting incidents Sweep 2: Timeline verification and decision point identification  Location: Korea  Weather: Winter  Time: Dec 2007 morning  Event: During push-back, B-747 flight back to Singapore, engine unable to start.  Cause of Defects: Starter unable to rotate  Decision Point 1: 30 mins to departure -  Option 1: Technical Flight delay (involving 400 pax, 3-hr down-time, spares may not be available)  Option 2: Use 1xair-blower to melt the ice (adopted)  Decision Point 2: 20 mins to departure –  Realized ice was melting slowing:  Option 3: Revert to Option 1 - Technical Flight delay (involving 400 pax, 3-hr down-time, spares may not be available)  Option 4: Use hammer to break the ice (adopted)  Decision Point 3: 15 mins to departure –  Observation: Bits of ice were “dropping off” : Hopeful…  Option 5: Blew ground air unit to maximum speed to drive the rotor  Observation: Starter unit came to live  Outcomes: Able to start the engine & departure as per schedule  Option 6: Call for immediate Technical Flight delay Critical Decision Method:B747

Sweep 3: Progressive Deepening (the story behind the story)  Perceptions:  If delay: SME “kena” – passengers complained, supervisors demanded explanation/report, admin loading to the ground crew, …  No logistic spares  Nature Instinct: Make good/rectify faults as the engine just need to start  Expectations:  Must NOT cause any damage to the rotor  To start the engine without causing flight delays  Judgements: Safety NOT an issue -  Usage of Air Blower – SME observed that the ice was catching the rotor and there was no point to change the rotor  Usage of Hammer – SME opined that hammer will create the vibrations with calibrated knocks to loosen the ice. Knocking must be near to the rotor (approximately 2” from the rotor blade)  Goals:  Start the engine by all means: no flight delays  Uncertainties:  Usage of Air Blower & Hammer – Not proven methodology & Not in the Manuals  Concerns:  Answerable to Stakeholders (Branding: Top Airlines in the World) Critical Decision Method: B747

Sweep 4: “What if?”: – Case 1: Ice not breaking up Continued blowing hot air to increase temperature to melt the ice – Case 2: Hammer calibrated wrongly & broke rotor Activated Technical Flight Delay – Case 3: If novice was in charge, how? Refer to Manual & delay flight – Case 4: If the time has been different, how? Longer Time – Monitor & wait for the ice to melt – Use Air Blower to blow longer – Will NOT use hammer Shorter Time – If Ice is melting, will increase temperature and delay the flight slightly – If Ice is NOT melting, will declare Technical Flight Delay – Case 5: What training will have to offer an advantage? Basic principles of working components – Case 6: What knowledge, information or tools could have helped? Availability of spares Know where to pull items from other operators Critical Decision Method: B747