Mount Cook Airline

1. Mount Cook Airline Safety Investigations & Education in an Airline Nathan McGraw 05 June 2010

2. Overview • Mount Cook Airline - our approach to safety • Tail icing investigation Mount Cook Operational Safety

3. Who are we? • Part of the Air NZ Group • Wholly owned subsidiary • Independent AOC • 11 x ATR 72-500 • 2,300 sectors per month • 10 scheduled destinations Mount Cook Operational Safety

4. Our Approach to Safety • We don’t rank safety: Safety is critical • Use SMS principals (formal SMS in development) • Proactive approach (don’t wait for an incident) • Investigate events that go well • Safety education is essential Mount Cook Operational Safety

5. Our Approach to Safety • Operational Safety (not Flight Safety or OSH) • Previously an ‘investigation office’ only • Op Safety team • Two pilots (F/Os) • Two cabin crewmembers • All current line crewmembers (minimum 50% line flying) • Safety focus (no fingers in other pies) Mount Cook Operational Safety

6. Our Approach to Safety • Cabin crew are an essential part of the team • Many investigations have a cabin crew aspect • Separate area of expertise • Non-technical approach • Non-management contact for line cabin crewmembers • Line cabin crewmembers have a voice (better buy-in) Mount Cook Operational Safety

7. Our Approach to Safety • Safety Advisors, not Investigators • Both pilots have training & examining backgrounds • Both pilots are FOs and have been Captains previously • Qualified military test pilot and instructor • Trained investigators • RABQSA accredited auditor • HF training (USC, ATSB) Mount Cook Operational Safety

8. Our Approach to Safety • Essential Qualities of a Safety Advisor • Integrity • Objectivity • Moral courage • Respected by crewmembers and management • High personal standards (sets an example) • Infectious attitude towards safety (generative approach) Mount Cook Operational Safety

9. Our Approach to Safety • Ratio of work 30% monitoring (processing data, reports) 20% investigations 60% safety liaison & education ____ 110% (we work very hard) • Focus on education improves credibility and buy-in •  credibility =  report quality & quantity Mount Cook Operational Safety

10. Safety Reports Maintaining Credibility Investigation Trust / Buy-in Positive Education Mount Cook Operational Safety

11. Our Approach to Safety • Safety Reports – our morning newspaper • All about trust (hard to earn, shattered in an instant) • Absolute avoidance of punitive action • De-identification, even when not requested • Responsible to the regulator for notification; but • Greater responsibility to our fellow crewmembers • Integrity (we do what we say we’ll do) Mount Cook Operational Safety

12. Our Approach to Safety • Safety Investigations - how can we do this better? • Evidence-based approach • Huge HF emphasis • Lots of tests for ‘reasonableness’ • Substitution tests to identify systemic factors • Absolute avoidance of punitive content Mount Cook Operational Safety

13. Our Approach to Safety • Safety Education – Give people the tools to be safe! • Op Safety Report: weekly report to management • Safety Snapshot: monthly occurrence bulletin • Aoraki Safety: biannual magazine • Op Safety website: library, links, resources • Classroom: HF module during annual CRM courses • All positive material – no preachy statements Mount Cook Operational Safety

14. Our Approach to Safety • Traditional Safety Office • Get summonsed when you’ve had an incident • Only produces investigation reports • Punishment for naughty pilots Message: Safety Office is a negative place • Our Op Safety office • Positive place (even during investigations) • Churns out positive safety material (learning emphasis) • Try to make safety interesting, enjoyable, and accessible Mount Cook Operational Safety

15. Recent Investigations • TCAS TA at Queenstown • GNSS Database Validity • Engine failure after takeoff • DG fumes in-flight • Severe turbulence (yes Peter, it’s coming) • Tail icing events Mount Cook Operational Safety

16. Tail Icing Events Important • Not suggesting that the ATR is unsafe in icing conditions • ATR has produced comprehensive & detailed information for operators and pilots • ATR icing procedures are robust and appropriate • Investigation is applicable to all aircraft types • Only significant points covered in this presentation Mount Cook Operational Safety

17. Tail Icing Events • NZ Climate • Polar Maritime (cold, moist flow) • Airframe icing at altitude (especially for turboprops) • NZ pilots generally knowledgeable about airframe icing • Icing all year – both events happened in late summer Mount Cook Operational Safety

18. Tail Icing Events • First Event • Freezing rain in climb between FL160 and FL170 (Marlborough Sounds) • Significant reduction in rate-of-climb to <200 fpm • Ice detection system alert • Immediate cruise descent to FL150 • Air was 5 °C warmer and all visible ice melted quickly • Flight continued at FL150 with no visible ice accretion Mount Cook Operational Safety

19. Tail Icing Events • First Event • After 15 minutes at FL150, loud bang and severe vibration from tail area • Vibration lasted for over 30 seconds but then ceased • Pilots disconnected AP and checked for controllability – all normal • Experienced crew – never encountered vibrations so strong • Suspected ice but diverted to Palmerston North due severity of vibration • Thorough maintenance inspection – no defects or abnormalities Mount Cook Operational Safety

20. Tail Icing Events • Second Event • Ice accretion earlier in flight • “Significant icing remained on the IEP” • Cruised in VMC • IMC on descent but VMC at 7,000 ft • All visible ice melted by 4,000 ft Mount Cook Operational Safety

21. Tail Icing Events • Second Event • No visible ice and +11 °C on the ground • All ice protection systems turned off (as per SOP) • Pilots planned for and briefed a non-icing landing • ‘Fish tailing’ on final approach • Unstable in pitch and yaw – difficult to stabilise and trim • Landed uneventfully Mount Cook Operational Safety

22. Tail Icing Events • Second Event • After disembarking, pilots noted significant ice on stabiliser • Ice on pneumatic boots (protected section), • Estimated 150mm forward of leading edge Mount Cook Operational Safety

23. Tail Icing Events • Analysis • Considered defects with flight controls, trims, autopilot, ice protection • Review of maintenance records – no defects or discrepancies • Functional test of pneumatic boots – no defects • Tail icing most likely contributing factor Mount Cook Operational Safety

24. Tail Icing Events • NASA Tail Icing Research (early 1990s) • Tail icing historically poorly understood • Icing accidents between 1950 & 1980 often misdiagnosed as wing stalls • Tail surfaces accrete ice earlier and faster than wings (sharper leading edge) • Propeller aircraft are more susceptible (particularly turboprops) • Possible to have ice on stabiliser with no other ice on airframe Mount Cook Operational Safety

25. Prop wash at higher angles-of-attack (for illustrative purposes only). Tail Icing Events • Stabiliser on turboprop aircraft often sits in prop wash • Higher velocity = lower temperature • Prop wash air can be up to 5 °C cooler than ambient • Tail can be in icing conditions, even if the rest of the aircraft isn’t! Mount Cook Operational Safety

26. Tail Icing Events • Design features which support tail icing (NASA) • Un-powered and aerodynamically balanced elevators • Pnuematic de-icing boots in lieu of heated leading edges • Horizontal stabilisers with sharp leading edges • Large flap deflections (big change of relative airflow over tail) • These features are applicable to a lot of turboprops • Tail ice can be 3 – 6 times thicker than on the wings Mount Cook Operational Safety

27. Tail Icing Events • Findings – First Event • No maintenance defects or anomalies • Loud bang was likely tail ice breaking free in warmer air at FL150 • Vibration was likely airflow disruption over elevator due to ice breaking free unevenly • Gave the crew a real fright – a very unusual icing event Mount Cook Operational Safety

28. Tail Icing Events • Findings – Second Event • No maintenance defects or anomalies • Pilots followed SOPs exactly (passes substitution test) • Residual ice on the tail was very unusual • Aerodynamic instability on approach likely caused by tail icing • Pilots reported symptoms similar to an impending tailplane stall Mount Cook Operational Safety

29. Tail Icing Events • Symptoms of impending tailplane stalls (NASA) • Lightening of controls (particularly forward motion) • Difficulty trimming • Onset of pilot-induced oscillations due to change of control balance • Control buffeting (but not the airframe) Mount Cook Operational Safety

30. Tail Icing Events • Severe Icing QRH Checklist • Includes significant protections against tailplane stall (reduced flap landing) • Pilots used it only when in defined severe icing • Once clear of severe icing, pilots would resume normal ops and land with full flap (breaking the checklist) • Tail icing is possible without being in defined severe icing • Recommended that checklist be used whenever tail icing is suspected (regardless of whether icing was severe or not) Mount Cook Operational Safety

31. Tail Icing Events • Recommendations • Training module for tail icing • Icing exercise in simulator that results in a reduced flap landing • Use severe icing checklist (including reduced flap landing) if tail icing is suspected, even if airframe is visibly clear of all ice Mount Cook Operational Safety

32. Tail Icing Events • Results • Good support from ATR during investigation • Great company support, particularly Flight Ops and Training • Enthusiastic uptake from training team • Pilots now routinely report landing with reduced flaps after significant ice encounters • Investigation resulted in positive training and tangible results Mount Cook Operational Safety

33. Thanks!