Night Mountain Rescue Hoist Training Fatal CFIT

Posted by on Dec 28, 2022 in Accidents & Incidents, Helicopters, Human Factors / Performance, Regulation, Safety Management, Special Mission Aircraft | 0 comments

Night Mountain Rescue Hoist Training Fatal CFIT (SAF Hélicoptères Airbus EC135T1 F-HJAF)

On 8 December 2020 Airbus EC135T1 F-HJAF of SAF Hélicoptères suffered a Controlled Flight into Terrain (CFIT) at c 5,900 ft altitude in mountainous terrain in the French Alps during mountain rescue training.  The helicopter was destroyed, 5 occupants died and the pilot was rescued with serious injuries.

SAF Hélicoptères Airbus EC135T1 F-HJAF CFIT: Wreckage (Credit: BEA)

The Accident Flight

The Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile (BEA) explain in their 109-page safety investigation report, issued 14 December 2022, that six training flights were planned, namely two morning, two afternoon and two night flights.

These were conducted under an EASA Part-SPA.HHO specific approval for hoist operations.  The operator’s SPA.HHO training approval had been issued by regulator the previous Friday, 4 December 2020. The operator had however previously been conducting rescue hoisting under a national approval and the trainees therefore had prior mountain hoisting experience.  The exercises followed a day of classroom training on Monday 7 December 2020 and were…

…designed for the trainees to obtain the SPA.HHO “Initial” and “Advanced Mountain” approvals taking into account their [prior] experience.

The instructor pilot (who was also the NPCT [Nominated Person for Crew Training, appointed just 4 months earlier]) and the instructor hoist operator (who was also the NPFO [Nominated Person for Flight Ops]) were the only two people trained to deliver the training they had set up.

There was a potential time pressure as the mountain rescue season was set to start on 12 December 2020 and two trained crews were contractually required.

At the end of the afternoon, the two crews held a briefing before the two night flights. The review of the weather forecast had revealed that there would be a disturbance bringing snow in the evening.

For the night flights, the crew was to consist an instructor pilot [the NPCT], a pilot under instruction, an instructor hoist operator [the NPFO), a hoist operator under instruction and two rescuers who were to be hoisted.  After the first night flight a second pair of trainees were to replace the first.

Given the arrival of this [weather] disturbance, the very short exercise programme (three hoist operations) and the proximity of the exercise site (situated 3.2 NM SE [of Albertville aerodrome] at an altitude of 6,000 ft), all the persons concerned took the decision to carry out the two flights one after the other and to switch crews with the rotor turning at the end of the first night flight.’

It was a moonless night.

The aeronautical night (30 min after sunset) started at 16:22 at [near-by] Chambéry.

The second night flight commenced at 17:00. 

The instructor pilot had 6,200 hours experience, 1,513 on type.  The pilot under instruction had 5,493 hours experience, 663 on type. 

EC135T1 F-HJAF, manufactured in 1998, was equipped with traditional analogue avionics and didn’t have an autopilot.  It did have a HELIMAP moving map display connected to a Trimble GNSS.

On the way to the site, the instructor [pilot] identified fog banks on the northern slope of the
mountain located to the north-east of the exercise site.

On arrival the same three approaches and hoist exercises as conducted during the first night flight were repeated. 

Although the town lights in the distance were visible, they were only sufficient for choosing a heading or determining a position with respect to remote reference points. The dark, moonless night would have made it difficult for nearby terrain to be discerned. The helicopter lights, while manoeuvring at low speed or in near-hover were needed to distinguish and avoid obstacles close to hand.

In addition, in the previous days, snowfalls had completely covered the ground and vegetation in this area making it particularly difficult to distinguish potential cloud banks and to assess their proximity.

Upon completion of the exercises:

The recorded flight path showed that the pilot flying [the pilot under instruction] then flew out of the hover. He headed northwest, gained speed and then made a left-hand turn by around 180° while staying in level flight.

It was at this point that the instructor [pilot, the pilot monitoring] turned to the other four occupants located at the rear of the helicopter. According to the instructor, the flight path was stabilised and there was no obvious risk before he turned around.

However:

The helicopter headed towards the mountainside.

SAF Hélicoptères Airbus EC135T1 F-HJAF CFIT: Accident Location (Credit: BEA)

The main rotor blades hit the top of a first row of conifers. The airframe of the helicopter then collided head-on with a second row of trees, then with the snow-covered ground.

SAF Hélicoptères Airbus EC135T1 F-HJAF CFIT: Accident Site (Credit: BEA)

During this second collision, the instructor pilot in the front left seat was ejected from the helicopter and fell into the snow. Although severely injured, he managed to telephone the SAF Hélicoptères operations department and inform them of the accident.

According to the injured pilot the accident site became enveloped in cloud within 30 minutes.  A mountain rescue team reached the pilot on foot at 20:48 after two SAR helicopters were foiled by the weather.

The BEA Safety Investigation

The BEA were only able to reach the accident site two days later due to the adverse weather conditions, courtesy of a Gendarmerie helicopter.  The wreckage could not be recovered until 21-22 April 2021 when a HESLO AS332 was used.

SAF Hélicoptères Airbus EC135T1 F-HJAF CFIT: Wreckage Removal by AS332 HESLO (Credit: BEA)

No pre-impact defects were identified with the aircraft.

In a workshop with various mountain rescue and hoist operations stakeholders in June 2021, industry practices were discussed:

…it appeared that simultaneous training of the pilot and the hoist operator was not common practice.

Although not allowed for in the operator’s Operations Manual (OM):

The decision to provide the “Initial” and “Advanced Mountain” training courses simultaneously for daytime flights was understandable given the experience already acquired by the trainees.

The BEA say same logic could not be applied to the night training.  The BEA note that:

At the time of the accident flight, the pilot in training, given his seniority within the company, probably had good daytime knowledge of the area and surrounding references. However, he had little experience of night flight. Moreover, it is probable that the night experience he had acquired was principally based on air ambulance or ferry flights.  [T]he software used by the operator did not record the number of night hoist operations carried out…

As a consequence, the pilot was probably acquainted with the light references corresponding to the conventional routes and surroundings of the aerodrome. It is likely that he was less at ease identifying or keeping track of them outside these known environments, in particular, near the terrain.

[N]ight flight, especially in the mountains, is more exposed than day flight to certain risk factors such as a reduction in visual performance, visual aberrations or spatial disorientation.

The instructor [pilot] may have overestimated the pertinence of the night flight experience of the pilot in training with respect to the intended training flight, which presented particular difficulties (flying close to mountainous terrain in moonless night conditions).

However, the operator explained to BEA that they had not in fact intended to actually conduct hoisting at night but had requested day night approval so that flights could transit back and land after dark.  Arguably there was therefore no need for the night hoisting exercises at all.

The objective of the two night flights, including the accident flight, could not be clearly defined during the investigation. Indeed, although these flights had been recorded in the SPA.HHO training flight schedule and the flights were carried out according to this schedule, the statements gathered from the instructor as well as from the pilot and the hoist operator of the first night flight do not completely corroborate with each other as to the objective…

The BEA say the “lack of precision concerning the operational context…raises the question as to the basis on which SAF Hélicoptères”:

  • Carried out the safety impact assessment for the SPA.HHO approval.
  • Defined the associated training and determined that the pilots in training had enough experience – in particular night flight experience – for them to follow this training

The safety impact assessment (only includes in the report in French):

  • Was not taken as an opportunity to explore the risk factors specific to both night and mountain operations.
  • Focused almost exclusively on the hoist operation phase which characterises SPA.HHO operations, without explicitly addressing the arrival at and departure phases from the mission site, which involves forward flight close to the terrain.
  • Did not include a section specific to training flights undertaken as part of this SPA.HHO approval.

On the last point, ‘lack of training and recent experience’ was actually a hazard in its own right in the operator’s risk assessment.

Crew experience was proposed as a barrier to address three of the identified risks, and crew training as a barrier to address six of them.

BEA also noted that that the NPFO and the NPCT positions “consistently have a high workload and that a lack of deputies can be critical, especially when new operations, new training courses or new aircraft are introduced”.

The company’s management was probably unable to identify or appreciate the pressure induced by the contractual commitments, and the pressure which its managers, and in particular the NPCT and NPFO put on themselves. This pressure may have led to them deviating from the conformity requirements which they normally guarantee and may have compromised their ability to effectively manage certain risks.

In particular, it is probable that they overestimated the night experience of the pilot in training…

In relation to the weather that night…

…it appears that the meteorological conditions at the time of the accident flight were better than those indicated by the forecast…

Nevertheless, ahead of the disturbance, due to lower temperatures and higher humidity, it is possible that local phenomena may have developed on the mountainsides, such as mist or fog banks or fractus cloud banks close to the terrain.

The BEA note that HELIMAP, while useful for HEMS night transit flights…

…tends not to be used during mountain rescue flights. The map library installed only offers one 1:500,000-scale base map with relatively few details compared to the navigational precision required…

However (emphasis added):

If a night helicopter hoist operation is performed in a mountainous area below the terrain ridges, in the absence of conventional radio-navigation means and easy-to-identify visual references, a positioning system such as HELIMAP can be an additional aid for the pilot to locate himself in relation to the surrounding terrain and obstacles and to define a safe route to follow.

Crucially though…

…the map base used needs to be appropriate for the operations. [I]f the pilot had used HELIMAP, the proximity to obstacles and terrain would have been difficult to detect given the level of detail shown on the available map (ICAO VFR map to a scale of 1:500,000).

Based on reconstructing the flight paths:

…the difference between the two night flights revealed two different manoeuvring decisions: during the second flight, the times (almost identical to those of the first flight) indicated that the pilot flew in a smaller perimeter at lower speeds and with larger bank angles during the turns, which, at night and with few visual references, could lead to a feeling of “discomfort” and a more “bumpy” flight. In addition, it appeared that the racetrack patterns performed left little margin in the event of technical failures (e.g. engine failure).

On survivability:

The instructor’s survival can be explained by the fact that he was ejected from the helicopter during the last collision with the trees, the very low height at which this occurred and the thickness of the snow cover on the ground, which cushioned the fall.

SAF Hélicoptères Airbus EC135T1 F-HJAF CFIT: Wreckage (Credit: BEA)

BEA Conclusions

After a flight described by the instructor as an assessment flight as part of the night helicopter hoist operation training, the pilot left the site and made a left-hand turn of approximately 180° while remaining in level flight. The flight appeared to be controlled until the collision with the trees. It was not possible to determine the reasons why the pilot initiated this turn. It cannot be ruled out that this turn was initiated to avoid clouds and fog banks which had appeared near the exercise site.

It was not possible to determine the exact reasons why the pilot continued the left-hand turn until the collision with the trees and then the ground. This could be explained by the pilot losing situational awareness regarding the position of the helicopter in relation to the terrain.

The BEA identify the following factors that may have contributed to the pilot’s possible loss of situational awareness of the position of the helicopter in relation to the terrain:

  • The partial or total disappearance of the distant reference points formed by the town lights in the valley due to the deterioration of the weather conditions.
  • The loss of external visual references in the final phase of the flight path due to reduced light conditions on a dark, moonless night, which did not allow the pilot to make out obstacles and the surrounding terrain.
  • The instructor temporarily suspending his monitoring of the flight path in a context where the pilot had limited recent and total night flight experience with respect to the specific difficulties of this flight phase, in immediate proximity with the terrain in dark night conditions in which it was not possible to distinguish close obstacles. As they moved away from the hoist operation site, the instructor considered the path initiated to be consistent with a safe return to the aerodrome, and turned around to exchange with the other occupants of the helicopter.

They also note that:

It cannot be ruled out that a sensory illusion phenomenon during a dark night may have contributed to the pilot possibly losing situational awareness of the position of the helicopter in relation to the terrain.

The BEA identify the following factors that may have contributed to the the decision to undertake an instruction flight with reduced safety margins in a hostile environment (mountain, dark night, deteriorating weather conditions forecast):

  • Insufficient consideration given to the pilot’s little recent and total night flight experience in a mountainous environment in immediate proximity with the terrain.
  • Underestimation of the flight risks potentially caused by the time constraint to complete the training. This constraint could be explained by the desire to have qualified crews available to meet the requirements for mountain rescue operations the following week. This may have led the instructor/NPCT to propose a shortened training programme that was supposed to enable the trainees to obtain all the SPA.HHO approvals, although this situation was not provided for in the OM. While SAF Hélicoptères may have considered that the pilot’s experience in daytime mountain flying allowed for this shortened programme, this reasoning does not seem to be transposable to night training flights.

The BEA identify the following factors that may have contributed to self-imposed pressure on the management team:

  • The company’s management (including the instructor hoist operator responsible for flight operations and the instructor pilot responsible for crew training) insufficiently taking into account the time necessary to include SPA.HHO procedures in the OM and for the civil aviation authorities to give its approval of these operations, given the planned contractual dates for setting up these operations.
  • The work overload generated by the setting up of SPA.HHO operations and the associated training.

The BEA do not comment on whether the regulators review of the SPA.HHO application had the unintended consequence of adding pressure or indeed if was adequate.  Nor do they comment on the value of Night Vision Imaging Systems (NVIS) that were not in use.

SAF Hélicoptères Airbus EC135T1 F-HJAF CFIT: Accident Site (Credit: BEA)

Safety Actions Taken

The day after the accident, the regulator suspended the operator’s SPA.HHO approval (granted just days before).  On 5 January 2021, having made modifications to their SPA.HHO training programme, the operator requested that suspension be lifted.  That occurred on 26 January 2021, for daytime operations only.

Since the accident, the operator increased their resourcing, in particular:

  • the appointment of deputies to the different nominated persons;
  • the appointment of a flight safety officer for certain specific activities (EMS, lifting operations [HESLO]  and rescue operations); 
  • increasing the number of people in charge of safety and conformity [i.e. compliance];
  • creation of a design office [sic] whose tasks include improving documentation, operational studies and safety analyses.

BEA also raised two safety recommendation to the operator in relation to safety management and risk assessment.

Our Safety Observations

As well as another reminder of the hazards involved in night training, this accident is also a good reminder on the need to actively use your Safety Management System (SMS) as part of a comprehensive Management of Change (MOC) and not simply file a risk assessment that changes ‘reds and yellows’ to ‘yellows and greens’.

The safety actions taken, all involving adding people, belie the idea that an SMS (or a management System) more generally is readily scalable.  Smaller organisations, with lower levels of organisational redundancy and fewer independent checks and balances, are both disproportionately vulnerable to commercial pressure and less capable of fully exploiting an SMS.

Safety Resources

The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn.  You may also find these Aerossurance articles of interest:

See also:

Aerossurance has extensive air safety, operations, SAR, HEMS, HHO, airworthiness, human factors, aviation regulation and safety analysis experience.  For practical aviation advice you can trust, contact us at: enquiries@aerossurance.com

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