Beware Last Minute Changes in Plan
Beware Last Minute Changes in Plan The US National Transportation Safety Board (NTSB) has recently reported on an EC130 helicopter accident that illustrates the dangers of last minute changes in plan that are not fully planned or risk assessed. The Wire Strike Accident The accident occurred in Colorado on 3 July 2015 to Airbus Helicopters EC130B4, N974BR of now defunct Aspen Heli Charter. The NTSB report: The pilot had flown multiple trips into and out of the ranch prior to the accident. He also had seen wires in the area and had a discussion with local fishing guides regarding the location of wires in the area. As the pilot was preparing to depart the ranch with the last load of passengers he was approached by a guide who wanted to video the helicopter for their website. The pilot agreed and after lifting off, made a pass near the ranch for the video. The pilot stated he was flying toward the mountains when he heard a “small ting” and he knew the helicopter contacted a wire. He made an uneventful off airport landing in a nearby clearing. Although the pilot stated he never saw the wire it was later determined the helicopter contacted was a small copper static wire. A postaccident inspection of the helicopter revealed two of the three main rotor blades were beyond repair, at least two of the Fenestron blades were beyond repair, and the entire Fenestron stator blade assembly needed to be replaced. Fortuitously no one was injured and the awaiting tour party, who had been on a fly-fishing trip, returned to Aspen by Jeep. Other Cases of Last Minute Changes of Plan Aerossurance has previously discussed a fatal helicopter accident where a last minute distraction at a mining camp and a recent change in work practice fatally combined: When Habits Kill – Canadian MD500 Accident and a military accident where adding passengers to a training sortie at short notice had fatal consequences ‘Procedural Drift’: Lynx CFIT in Afghanistan. A request to extend the planned mission and a last minute change of aircraft type were factors on a Japanese accident: Fatal Police Helicopter Double Engine Flameout Over City Centre. We have also discussed the lessons of an experimental aircraft accident were the full implications of a hardware change were not understood: Breaking the Chain: X-31 Lessons Learned UPDATE 11 September 2016: Another case where a last minute change of plan was partly responsible for an accident: Final Report: AS365N3 9M-IGB Fatal Accident UPDATE 25 June 2017: Similarly, during an air ambulance positioning flight: Impromptu Flypast Leads to Disaster Wire Strike Resources We have written on other wirestrikes: Sécurité Civile EC145 SAR Wirestrike Firefighting Helicopter Wire Strike Helicopter Wirestrike During Powerline Inspection Fatal MD600 Collision With Powerline During Construction Fatal Wire Strike on Take Off from Communications Site Fatal Wisconsin Wire Strike When Robinson R44 Repositions to Refuel UPDATE 26 July 2020: Impromptu Landing – Unseen Cable UPDATE 20 September 2020: Hanging on the Telephone… HEMS Wirestrike UPDATE 23 January 2021: US Air Ambulance Near Miss with Zip Wire and High ROD Impact at High Density Altitude UPDATE 5 March 2021: Wire Strike on Unfamiliar Approach Direction to a Familiar Site UPDATE 21 August 2021: Air Methods AS350B3 Night CFIT in Snow UPDATE 14 August 2022: Second Time Unlucky: Fatal Greek Wirestrike High-Wire Illusion UPDATE 3 September 2022: Garbage Pilot Becomes Electric Hooker UPDATE 4 February 2024: HEMS Air Ambulance...
read moreMisfuelling Accidents
Misfuelling Accidents Misfuelling aircraft with kerosene based Jet A-1 rather than Aviation Gasoline (AVGAS) continues to be a source of accidents. PA31 15 Sept 2015 Manitoba The Canadian Transportation Safety Board (TSB) has recently released an update on the 15 September 2015 accident involving twin engined Keystone Air Service Piper PA31-350 Navajo C-FXLO at Thompson, Manitoba. Shortly after takeoff the aircraft experienced a malfunction and the crew attempted to land back at Thompson. The aircraft impacted terrain less than 1 nautical mile from the airport. All 8 persons on board survived. The TSB say: The ongoing investigation has confirmed that the aircraft received an incorrect type of fuel in Thompson, Manitoba, prior to departing for Winnipeg. The twin piston-engine aircraft requires aviation gasoline (AvGas), but was re-fueled with turbine engine fuel (Jet A1). The aircraft was destroyed by impact with trees and terrain; however, the aircraft cabin section remained largely intact. Almost all of the fuel was dispersed throughout the crash site from ruptured fuel cells but a sufficient quantity remained to obtain samples. There was no post-impact fire. The occupants sustained varying serious injuries but were able to assist each other and exit the aircraft. UPDATE 10 November 2015: Transport Canada has now suspended the operator’s AOC (for a third time since 2002). UPDATE 8 September 2016: The TSB release their report. The refuelling technician, who had been working for the fuelling company for a just over a month, and had no prior aviation experience, had fuelled another aircraft with Jet A1 before the Keystone aircraft arrived and drove the Jet A1 truck to where the PA-31 had parked. The aircraft commander had intended to relay the fuel requirements to the technician, but the Co-Pilot, who was escorting passengers, had noticed that the fuel technician was having trouble with the fuel filler openings. The Co-Pilot assisted the technician and asked for required fuel. The Captain overhead this conversation and so did not talk to the refueller. Neither pilot noticed that the truck was a jet fuel truck. The technician did not spot the aircraft placard specifying aviation gasoline. When the technician couldn’t get the flared fuel filler nozzle to fit, he switched to a narrower nozzle, defeating a defence to prevent Jet A1 being used on a piston engined aircraft, but was sometimes required on aircraft that needed Jet A1. Prior to departure, the Captain returned to the fuel providers office to collect the fuel slip but it was unoccupied The crew then performed an abbreviated check before taking off. TSB say: The Esso fuel dealer at Thompson Airport was Mara-Tech Aviation Fuels Ltd, which operated the Imperial Oil owned facility and equipment under an aviation dealer agreement. In addition to its day-to-day operation of the facility, Mara-Tech was responsible for staffing the facility and training the employees. Training materials were supplied by Imperial and consisted of a series of CDs or VHS tapes whose content was organized into modules. Each module was accompanied by a corresponding multiple-choice quiz. Aviation dealer agreements require that fuel dealers adhere to Imperial’s operating standards and procedures. Under the aviation dealer agreement, fuel dealers have a licence to use Imperial brand trademarks, such as Esso and Esso Aviation, in marketing their businesses. The [fuel technician’s] training consisted of reading the Imperial training material, viewing the CDs, and completing the corresponding multiple-choice quizzes. Additional certifications, such as Airside Vehicle Operator’s Permit and Transportation of Dangerous Goods, were administered by the manager at Mara-Tech’s Thompson facility. The...
read moreFrench Skyscraper HESLO: Helicopter Underslung Load
French Skyscraper HESLO: Helicopter Underslung Load A stunning video, from Bouygues Construction, shows the construction of the the tower on top of the €124 million Incity building in Lyon, the third highest in France. The last two components of the tower were lifted into place by an Airbus Helicopters AS332C helicopter on Sunday 21 June 2015 as a Helicopter External Sling Load Operation (HESLO). The spire, which is 50 metres high and weights a total of 25.9 tonnes, took the building to its final height of 200 metres. Aerossurance has previously written about the replacement of a TV antenna on a 153m tower in Croydon South London by helicopter, the use of helicopter human external cargo by a power company in California and a UK lighthouse support contract. Also see our articles: What the HEC?! – Human External Cargo, Keep Your Eyes on the Hook! Underslung External Load Safety UPDATE 2 July 2020: Erickson videos: Aerossurance has extensive air safety, helicopter operations (inc HESLO) and contracting experience. For practical aviation advice you can trust, contact us at: enquiries@aerossurance.com Follow us on LinkedIn and on Twitter @Aerossurance for our latest...
read moreAerossurance Sponsors HF in Aviation Safety Conference
Aerossurance Sponsors Human Factors in Aviation Safety Conference Aerossurance is pleased to sponsor the Chartered Institute of Ergonomics & Human Factors’ (CIEHF) Human Factors in Aviation Safety Conference that takes place at the Radison Blu Hotel, East Midlands Airport, 9-10 November 2015. Aerossurance was keen to sponsor this event as it is such an excellent independent professional forum for discussion and exchanging of ideas on the very latest research, development and application of Human Factors in Aviation Safety. The 2 day event is just £199 (or £129 for one day) excluding VAT and includes a period of free membership of CIEHF. To book a place click here. The conference was doubled from 1 to 2 days after the organising committee reviewed over 50 high quality submissions. Monday November 9th Time Title Presenter 09:30 Registration 10:00 Welcome Address TBC 10:10 Developing a safety culture at EasyJet Sian Evans, Easyjet 10:30 Human Factors and Aircraft Ground Handling Loading Activities Rebecca Grant, Coventry University 10:50 Culture and Decision-Making Steve Scott, Coventry University 11:10 The assessment of just culture in civil aviation – learning from work on High Reliability Organisations Colleen Butler, Health and Safety Laboratory 11:30 Removing the error, from pilot error Donough Wilson, Coventry University Technocentre 11:50 Discussion and questions 12:10 Lunch 12:50 Understanding and mitigating rate and scale of change within the aviation industry. Jocelyn Clark, NATS 13:10 Tightening the link between safety and human factors in design Andrew Kilner, Eurocontrol 13:30 NATS Automation Principles: The Practicalities of Advanced Air Traffic Controller Assistance Tools. Lisa Aldridge, NATS 13:50 Feeding Human Performance into Design – Learning Lessons from SESAR Renee Pelchen, Eurocontrol 14:10 Discussion and questions 14:30 Break 14:50 An Appropriate Framework For The Safety Assessment of UAS Ground Systems used in UK Civil Aviation Applications Bob Bastow, BAE Systems – Defence Information 15:10 Integrating Unmanned Aircraft Systems into current and future airspace Fiona Cayzer, BAE Systems 15:30 Key Human Factors trends in UK military aviation Victoria Cutler, Royal Air Force Centre of Aviation Medicine 15:50 Human-Computer Interactions in Aviation: Pilots’ Visual Behaviour, Attention Distribution, Situation Awareness and Decision-making during Flight Operations Wen-Chin Li, Cranfield University 16:10 ‘Doing more with less’ – Single operator control of multiple UAVs Dale Richards, Coventry University 16:30 – 17:00 Discussion, questions and close 17:00 Drinks reception Tuesday November 10th Time Title Presenter 08:30 Registration 09:00 Pilot Monitoring Skills – the final safety net Jo Davies, ESE Associates Ltd 09:20 By products of commercial pressure: Human factors implications of fuel savings policies for airline operations Jorge Delgado, Independent HF Consultant and A330 Captain 09:40 A Human Factors Review of Pilot Training in UK Aviation Georgina Fletcher, Frazer-Nash Consultancy 10:00 Putting the Science Back into CRM; Promoting Distributed Cognition on the Flight Deck Don Harris, Coventry University 10:40 Break 11:00 Team and Collective Training Needs Analysis for Single Pilot Operations John Huddlestone, Coventry University 11:20 The Challenges and Opportunities for Crew Human Factors Training David Moriarty, Zeroharm Solutions 11:40 Mode Confusion; the Nemesis of Uniformity David Thompson, Wessex Human Factors Ltd 12:00 Discussion 12:20 Lunch 13:00 Using STAMP to bridge the gap between Human Reliability Analysis and Technical System Safety Peter Gibson, BAE Systems 13:20 A systematic safety work method for addressing blind spots in accident / incident investigation Jonas Lundberg, Linköping University 13:40 The Geometry of NMAC Brian Peacock, SIM University 14:20...
read moreCritical Maintenance Tasks: EASA Part-M & -145 Change
Critical Maintenance Tasks: EASA Part -M & -145 Change Commission Regulation (EU) 2015/1536 was issued on of 16 September 2015. Technically it amends Regulation (EU) No 1321/2014 “as regards alignment of rules for continuing airworthiness with the ‘Basic Regulation’ Regulation (EC) No 216/2008“. Critical Maintenance Tasks (CMTs) One of the most important parts of the amendment relates to CMTs, which are defined as: …a maintenance task that involves the assembly or any disturbance of a system or any part on an aircraft, engine or propeller that, if an error occurred during its performance, could directly endanger the flight safety. The European Aviation Safety Agency (EASA) has said that this change: …addresses a safety issue related to the risk of errors made during the performance of critical maintenance tasks and the need for maintenance organisations to implement methods to capture those errors before the certificate of release to service is issued. The change primarily enhances M.A.402 for Continuing Airworthiness Management Organisations (CAMOs). It also introduces 145.A.48 on the Performance of Maintenance for maintenance organisations (with 145.A.65(b) adjusted to be consistent with 145.A.48), which include tool control. Previously the expectation would be that the CAMO would ensure that M.A.402 defined standards were achieved by the maintenance organisation. Now effectively they are both accountable, the Part-145 to ensure the requirements are met and the Part-M to assure they are. Note: M.A.402 (a) previously referred to ‘flight safety sensitive maintenance tasks’ and 145.A.65 (b)(3) to ‘critical systems’. For background and the history of the rule making see: Terms of Reference for the Rule Making Team: Review Group ToR RMT.0222 (MDM.020) – Issue 1 Notice of Proposed Amendment: NPA 2012-04 Comment Response Document: CRD 2012-04 (193 comments were received) Opinion 06/2013 – Explanatory Note Draft amendment to Commission Regulation (EC) No 2042/2003 The NPA was in part prompted by following three safety recommendations addressed to the Agency: AIBN recommendation 12/2006, Report on the aircraft accident at Bergen Airport Flesland, Norway, on 31 January 2005 involving ATR 42-320, OY-JRJ, operated by Danish Air Transport, when control problems were experienced an elevator bolts loosened and fell out. The self-locking nuts were not tightened with the required torque. UK AAIB Safety Recommendation 2005-123 in Report 3/2005 on the serious incident to Boeing 757-236 G-CPER, operated by British Airways, on 7 September 2003. Maintenance errors that had culminated in the failure to reinstall two access panels on the right-hand outboard flap and incorrect engine oil top up. UK AAIB Safety Recommendation 2006-030 AAIB Bulletin: 11/2006 EW/C 2004/10/03 on the fatal accident to a privately operated Mooney Aircraft Corporation M20J, G-EKMW. A defect was discovered within the engine’s dual magneto, which had recently been refitted following a 500 hour inspection, affecting both ignition systems. This led to a loss of power shortly after take off and the aircraft impacting the ground while attempting to return to the airfield When discussed at the EASA Management Board, issue of whether the Type Certificate Holder was better placed to identify critical tasks. EASA clarified that this text is dealing with errors that occur during performance of maintenance, hence the responsibility is a continuing airworthiness one. The associated AMC and GM is expected to be published this autumn. However CRD 2012-04 indicates what can be expected. In particular the AMC and GM to 145.A.48 will cover implementing maintenance error capturing methods, that may include Independent Inspections and other techniques such as functional checks. Other Changes Although we...
read moreThe Missing Igniters: Fatigue & Management of Change Shortcomings
The Missing Igniters: Fatigue & Management of Change Shortcomings On 15 September 2015 the UAE General Civil Aviation Authority (GCAA) issued their investigation report into a Serious Incident that affected both engines of a Dash 8. Their report highlights the importance of Management of Change both at a macro level, when undertaking corporate restructuring (highly topical for air operators in the oil and gas sector with $50 / barrel oil) and at the micro level, when introducing new tasks. It is also the latest of a series of investigations to discuss maintenance personnel fatigue and alertness. The Incident Flight On 9 September 2012, Bombardier Dash 8 / DHC-8-315Q A6-ADB, operated by Abu Dhabi Aviation and chartered by a local oil and gas company, departed Abu Dhabi International Airport on a scheduled 35 minute passenger flight to Das Island, about 100 nm away and home to multiple oil and gas facilities. A crew of 3 and 46 oil and gas workers on board. Several minutes intro the flight, a concerned passenger informed the cabin crew member about paint blisters forming on the right hand engine inboard cowling. Although no fire warnings were generate the crew decided to return to the international airport and landed 10 minutes after take off. It was only after a safe landing that it was discovered that similar damaged had occurred on the left hand engine outboard cowling too. The engine cowlings were damaged because of: …of hot engine gases escaping through an open igniter boss on the engine casing. The hot gas was impinging on the nacelle, engine case drain line and engine support strut. The Maintenance History – Management of Change at the Micro Level The operator has suffered from unscheduled engine removals due to environmentally induced performance deterioration. Several engine wash options are available for the Pratt & Whitney Canada PW123. The operator had been conducting turbine washes since May 2009. Until December 2011, these were conducted using a task card, that contained technical instructions and was used to record the sign-off by both mechanic and certifying engineer. However to “reduce paperwork” and “improve process efficiency” these were replaced by a procedure that described the task and required a technical log entry, signed just by the certifying engineer. In July 2012 supervisors locally, without reference to management, decided to trial doing a compressor wash at the same time as a turbine wash on one engine. As the investigators note, unfortunately the trial was briefed verbally and inconsistently and conducted in an even less controlled manner than the compressor washes as: …the work was being performed based on experience alone, and without any referral documentation from the AMM [Aircraft Maintenance Manual] to perform the physical task. In addition, the work was being conducted without any sign-off by the mechanic, or the engineer, and without any updates being entered into the electronic data system of the Operator. They go on to report that: On the night prior to the Incident flight, the duty Engineer in charge of the shift had physically prepared both engines for turbine washes… He removed engine access panels 415AL and 425AL, the igniter leads and the left igniter from each engine. The removed igniters were left inside the recess of the engine compartment without placing them in protective bags. The duty Engineer returned to the ‘control office’ where he proceeded to update the electronic data system for work done inside the hangar. He allocated two mechanics to perform...
read moreB787 GEnx Fan Shaft Failure
B787 GEnx Fan Shaft Failure The very day a British Airways Boeing 777-200 G-VIIO suffered an uncontained GE GE90 engine failure and fire at Las Vegas, Nevada, the US National Transportation Safety Board (NTSB) coincidentally published the probable cause of another GE engine failure. The 2012 Failure On 28 July 2012 Boeing 787-8 Dreamliner VT-ANJ, ultimately destined for Air India, experienced a GE GEnx-1B67 contained engine failure (i.e. no debris penetrated the engine casing radially) during a taxi test by Boeing at Charleston International Airport (CHS), South Carolina. There were no injuries, the airframe received extensive minor damage (from axially ejected debris) and the airfield was temporarily shut after the failure caused a grass fire. The ~8 feet (2.4 m) Fan Mid Shaft (FMS), made in Japan by IHI, which connects the fan and Low Pressure Compressor booster stages to the Low Pressure Turbine (LPT), had failed aft of the forward retaining nut. Consequently the LPT had migrated aft resulting in extensive secondary damage, by design, as the blades contacted the stationary guide vanes (thus preventing a overpseed of the unloaded LPT). The Investigation The NTSB investigation determined that: Examination confirmed separation of the FMS adjacent to the lock nut face located at the aft most full thread root. The fracture exhibited features indicative of multiple failure modes: one progressive, and one instantaneous. About 85 percent of the fracture surface exhibited features consistent with progressive fracture. The remaining fracture surface showed signs consistent with instantaneous failure by overstress. Further examination revealed features consistent with environmentally assisted cracking (EAC) specific to GE 1014 ultrahigh strength steel. The FMS threads and the retaining nut were coated with a dry film lubricant, and grease or engine oil was used as an assembly aid. Although a lead based dry film lubricant was previously used on GE engine fan mid shafts, during development of the GEnx engine, the design was changed to incorporate a lead free dry film lubricant [Everlube 9002], and graphite grease [MolyDag 254] instead of the previously used engine oil as an assembly aid. Testing of specimens taken from the FMS, and comparison to other dry film lubricants used previously on GE 1014 ultrahigh strength steel indicated that the dry film lubricant used on the incident FMS absorbed moisture at a higher rate. Additionally, the combination of dry film lubricant and graphite assembly grease was shown to increase the corrosion rate of GE 1014. The Continued Airworthiness / Safety Action GE expeditiously introduced an Ultrasonic Inspection (UI) to scan the forward end of the FMS in the area of the threads where the fracture had occurred. A second cracked fan mid-shaft was discovered in mid-August 2012 on another GEnx-1B. The NTSB issued Safety Recommendations A-12-052 and A-12-053 to the Federal Aviation Administration (FAA) on 14 September 2012. The NTSB Recommendation Letter suggested that AirBridgeCargo 747-8 Freighter VQ-BLR might have experienced a similar FMS failure on one of its GEnx-2B67 engines, resulting in a rejected take-off in Shanghai, China on 11 September 2012. However within two weeks they had determined that a different LPT failure mode had occurred. Coincidentally Air India took delivery of their second 787 on 19 September 2012. On 21 September 2012, the FAA published Airworthiness Directive (AD) 2012-19-08. This AD required an initial ultrasonic inspection (UI) of the FMS before further flight and then a repetitive UI every 90 days. The AD applied to all GEnx- l B and GEnx-2B engines with particular part numbers of FMS...
read moreGulfstream G-IV Take Off Accident & Human Factors
Gulfstream G-IV Take Off Accident & Human Factors (N121JM) The US National Transportation Safety Board (NTSB) has highlighted a number of important human performance issues in a recent Board Meeting held to discuss a Gulfstream G-IV business aircraft accident. UPDATE 24 September 2015: The full final report is now published. The Accident On 31 May 2014, 3 crew and 4 passengers died when G-IV N121JM, registered to SK Travel LLC, and operated by Arizin Ventures LLC under Part 91 rules, was destroyed at the joint civil/military Hanscom Field (BED) in Bedford, Massachusetts, after a night-time high speed rejected takeoff and runway excursion. Aerossurance discussed the preliminary findings of the investigation in July 2014: Focus on Gust Locks After US GIV accident. The gust lock system is used to lock the elevator, ailerons and rudder when parked to protect against damage in gusting wind. Indeed, the failure to unlock the gust locks prior to commencing take off was a critical failure. This NTSB video illustrates the take off: The aircraft overran the 2,137 m (7,011 feet) runway, collided with approach lights and a localizer antenna, went through the perimeter fence and ended up in a small ravine 564 m (1,850 feet) from the end of the runway, where the post crash fire took hold. Among the dead was Lewis Katz, co-owner of the US’s third-oldest daily newspaper. the Philadelphia Inquirer. Katz died just days after agreeing a $88 million deal, with partner Jerry Lenfesto, be sole owners of the newspaper’s parent company. The flight crew were experienced. The aircraft commander had >11,000 total flight hours (with > 1,600 hours on the G-IV) and the first officer >18,000 total flight hours (with >3,000 hours on the G-IV). They had flown together for about 12 years, a fact which is worth noting when we discuss human performance matters below. The NTSB abstract on that accident is here. The NTSB determined that the probable cause of this accident was: … the flight crewmembers’ failure to perform the flight control check before takeoff, their attempt to take off with the gust lock system engaged, and their delayed execution of a rejected takeoff after they became aware that the controls were locked. Contributing to the accident were the flight crew’s habitual noncompliance with checklists, Gulfstream Aerospace Corporation’s failure to ensure that the G-IV gust lock/throttle lever interlock system would prevent an attempted takeoff with the gust lock engaged, and the Federal Aviation Administration’s failure to detect this inadequacy during the G-IV’s certification. From the NTSB abstract and presentations we observe five human performance aspects to this accident: Human Performance Aspect 1 – Omitting to Disengage Gust Locks During the engine start process, the flight crew didn’t disengage the aircraft’s gust lock sustem. This omission should not on its own be fatal as there where at other safeguards (one procedural, a status indication and a physical design feature) that should act as further risk controls. Human Performance Aspect 2 – Omitting a Flying Control Check The flight crew failed to perform a flight control check. This procedural control would have alerted them that the controls remained locked. It is noteworthy that when the NTSB reviewed flight data from the aircraft’s Quick Access Recorder (QAR), they discovered that this flight crew had failed to perform complete flight control checks before 98% of their previous 175 take offs. To the NTSB this indicated that this omission was “habitual”. The NTSB comment that: SK Travel [sic – note not Arizin Ventures] flight operations manual required...
read moreLoss of MV Derbyshire 9th September 1980
Loss of MV Derbyshire 9th September 1980 On 9th September 1980 the Bibby Line OBO (oil/bulk/ore) carrier MV Derbyshire sank during Typhoon Orchid in the South China Sea. All 44 people on board died. The Derbyshire, at 90,000 gross registered tons, remains the largest UK registered ship ever to be lost at sea. Until 1994 the location of the wreckage was not know and so the initial 1980 inquiry was relatively inconclusive. Following a survey of the wreck using the latest underwater search technology, a re-opened inquiry concluded in 2000 that a structural failure had occurred. This removed unfounded accusations of error by the Captain and crew. It also highlighted that vessels that only complied with the minimum requirements of the International Load Line Convention of 1966 posed an unacceptable risk to safety. This video describes the failure mechanism: UPDATE 9 August 2025: OceanGate Titan: Toxic Culture & Fatal Hubris Aerossurance has extensive safety management and accident analysis experience. Contact us at: enquiries@aerossurance.com Follow us on LinkedIn and Twitter @Aerossurance for our latest...
read moreHTAWS Technology: Friend or Foe?
HTAWS Technology: Friend or Foe? Technology has great potential to reduce aviation risk. The European Helicopter Safety Team (EHEST) issued a study in October 2014 on the safety value of technology. Terrain Avoidance and Warning Systems (TAWS) have proved highly effective at fixed wing Approach and Landing Accident Reduction (ALAR). On 20 February 2014, the Federal Aviation Administration (FAA) issued an extensive package of changes to Parts 91, 120 and 135 to improve Helicopter Emergency Medical Service (HEMS) safety that includes a requirement for Helicopter TAWS (HTAWS). While the adoption of HTAWS offers great potential safety benefit, its introduction, like any new technology, needs to be carefully considered. It may be tempting to simply see the introduction of such equipment as an incremental improvement in safety and simply base introductory training, for example, on the avionic manufactures’ technical publications for the equipment. However, there are wider potential impacts that need to be addressed when risk assessing the unintended consequences of introducing new technology. For example reducing the risk of one accident type may heighten the risk of another unless additional mitigations are in place. One example of this phenomena has been the introduction of flight deck automation, the subject of a July 2014 the Royal Aeronautical Society Rotorcraft Group conference, Technology: Friend or Foe? which we discussed in a previous article. A US HEMS accident in 2013 highlights an unintended consequence of HTAWS introduction. The Hospital Wing Accident On 22 October 2013, Airbus Helicopters AS350B3e (H125) helicopter N353HW, operated by the Memphis Medical Center Air Ambulance Service (doing business as Hospital Wing) was 18 minutes into positioning flight to collect a patient for an inter-hospital transfer, when it crashed near Somerville, Tennessee at 06:05 local time. There was a post crash fire (a subject Aerossurance has discussed recently). All three persons on board died. Two calls had been turned down during the night due to poor weather. At an airport about 2 miles from the accident site, a few clouds were observed at 800 feet agl, and a broken ceiling existed at 1,200 feet agl. As well as Garmin GNS530W TAWS the helicopter was equipped with Night Vision Goggles (NVGs) but was not equipped for operation under Instrument Flight Rules (IFR). In there final report the US National Transportation Safety Board (NTSB) state: …the helicopter was observed in a climb and in a right turn away from the observed course. The last data point indicated that the helicopter was on a course of 146 degrees and at 98 knots ground speed and at an altitude of 1,560 feet above mean sea level (msl) or about 1,116 feet above ground level (agl). A review of the helicopter’s ground track revealed two obstacles in the immediate vicinity, an unlit, nonoperational cellular tower, 140-feet tall, and a water tower, about 115-feet tall. Although recorded HTAWS data was not available, research and flight testing revealed that the pilot may have received an in-flight obstacle alert, prompting a climb. Considering the low clouds and night conditions that probably existed along the last segment of the flight’s track, it is likely that the pilot initiated a climb and inadvertently entered instrument meteorological conditions, where a loss of helicopter control occurred. The NTSB probable cause was: The pilot’s inadvertent encounter with night, instrument meteorological conditions while responding to an obstacle alert, resulting in an in-flight loss of helicopter control. The pilot was described by colleagues as “good pilot”, “well-liked” and “conscientious”. He flew...
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