Mount Cook Airline
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Transcript of Mount Cook Airline
Mount Cook Airline
Safety Investigations & Education in an Airline
Nathan McGraw
05 June 2010
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Overview
Mount Cook Airline - our approach to safety
Tail icing investigation
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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
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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
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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)
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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)
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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)
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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)
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Our Approach to Safety
Ratio of work30% 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
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Safety Reports
Investigation
Positive Education
Trust / Buy-inMaintaining
Credibility
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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)
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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!
Prop wash at higher angles-of-attack (for illustrative purposes only).
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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
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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
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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
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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)
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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)
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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
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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
Thanks!