Drift into Danger: AW109SP Night HLS Accident (G-RAYN, North Wales)
On 1 November 2022, a Leonardo AW109SP, G-RAYN, struck trees and crashed during a nighttime departure from an unlit landing site, in a field at Nantclwyd Lodge, near Llanelidan, Denbighshire.
AW109SP G-RAYN Accident Site (Credit: AAIB)
The UK Air Accidents Investigation Branch (AAIB) issued their safety investigation report on 18 April 2024.
History of the Day’s Operations
The pilot (who had 3,815 hours in total, of which 1,565 were on type) flew G-RAYN from Biggin Hill, Kent on the morning of 1 November 2022, to transport passengers to North Wales for a day’s game shooting.
The helicopter was owned by the lead passenger, but maintained and routinely operated commercially for third-parties by an approved air operator. When used privately by the owner, the flights were conducted as NCO flights (‘non-commercial air operations with other-than complex motor-powered aircraft’), using a pilot approved by the operator. This pilot had at that point worked for the operator for 5 years but was contracted directly by the owner for an NCO flight.
The pilot arrived at Biggin Hill at approximately 0645 hrs. His scheduled duty check-in time was 0700 hrs, 30 minutes before takeoff. While he had arrived early, much of that extra time was taken up with an unanticipated supportive conversation with a very recently bereaved colleague. The pilot self-briefed the weather, refuelled G-RAYN to approximately 600 kg of fuel and completed the prescribed pre-flight walk round check of the helicopter before taking off at 0727 hrs.
The helicopter landed at the owner’s private landing site at Lisvane, near Cardiff, at 0830 hrs to collect the passengers.
Because the flight was in support of the helicopter owner, who was a frequent flyer, the pilot did not consider that a refresher pre-flight safety briefing was required. He was not aware that some of the passengers had not flown in that model of helicopter before.
The flight to North Wales was uneventful and the helicopter landed near Llanelidan at 0920 hrs at a site listed in the operator’s Company Landing Site Directory (CLSD) as ‘LEA2’. The site was a flat area of grass adjacent to a row of trees and a shooting lodge.
AW109SP G-RAYN: LEA2 helicopter landing site, near Llanelidan, North Wales (Credit: via AAIB)
The ground sloped down and away toward several isolated trees to the north west, as indicated by the chevrons above.
The pilot departed to Hawarden aerodrome to refuel.
The return flight had originally been scheduled as a day departure at 1630 hrs. The takeoff became delayed until after just after nightfall (that occurred at 1718 hrs).
The pilot’s recollection was of having approximately 340 kg of fuel on board the helicopter before the flight and that he “took his time” after engine start to burn off additional fuel because he knew the helicopter would be close to its maximum takeoff weight (MTOW).
The landing site was unlit but the pilot was satisfied there were sufficient visual references available for him to safely conduct a vertical departure. The helicopter’s external lights were illuminating the area immediately around the helicopter and he could see what he described as a “vague horizon” ahead. The pilot judged that lights from the shooting lodge’s windows to his right would be an adequate lateral marker for the departure climb.
During take off from the unlit ad hoc landing site, at a height of approximately 40 ft agl, the main rotor blades struck trees. The helicopter hit the ground, rolling onto its right hand side.
AW109SP G-RAYN Accident Site (Credit: AAIB)
The fuel tanks maintained their integrity and there was no fire. The pilot shut down both engines and, with the assistance of onlookers, helped the five passengers to egress from the cabin. At least four had not fastened their seatbelts prior to departure. One of the passengers was seriously injured, and the other four escaped with only minor injuries.
The AAIB Safety Investigation: The Take Off, Night Training, Weight & Balance and Survivability
The investigators found that the helicopter had come…
…to rest at the base of a tree approximately 30 m from the shooting lodge. The main fuselage of the helicopter was intact but the tail boom had separated and been thrown forward of the point of ground impact.
AW109SP G-RAYN Position Before Take Off (Credit: via AAIB)
The AAIB identified no pre-impact issues with the helicopter and noted that upon impact the crashworthiness features of the AW109SP “appeared to function well”.
Investigators found that the accident resulted from the unintended rearward movement of the helicopter into trees during the intended vertical departure.
While night had fallen when he took off, the pilot assessed that he had sufficient visual references to safely conduct the intended departure manoeuvre. He described using light from the lodge’s windows as his lateral marker and establishing a forward visual reference with the aid of the controllable searchlight.
As the helicopter lifted into the hover, the lodge’s windows would have been in the helicopter’s approximate 3 o’clock position, in line with the pilot’s shoulders. Having turned into wind, the chosen lateral markers would have become more difficult to see, the pilot needing to look back over his shoulder to see the lights, approximately 30° behind his shoulder line.
AW109SP G-RAYN: Representation of pilot’s sightline to lodge windows during departure (Credit: via AAIB)
The lights’ change in relative position would have made it harder to discriminate between real and apparent drift, degrading their usefulness as markers. As the helicopter translated rearwards the lights would have appeared to move closer to their original orientation in the pilot’s 3 o’clock position.
During the time from lift-off until the pilot committed to the climb, the helicopter’s attitude rose to 6° nose-up and then stabilized at approximately 7° nose-up. This unintended nose-up attitude was higher than intended and not fully appreciated by the pilot. The rearward drift was consistent with performance modeling based on the recorded nose-up attitude and CG. AAIB considered that the pilot’s twisting to look at the lodge lights, may have inadvertently resulted in applying rearward pressure on the cyclic too (albeit AAIB call it a “control column”!).
Directing the searchlight beam straight ahead of the helicopter made it difficult to assess rearward movement by reference to the sightline shift from a close-in marker. Redirecting the searchlight 30-60° to the right could have helped detect longitudinal drift say AAIB.
The pilot could not recall having been trained or checked as proficient to operate from an unlit HLS at night during his employment with the operator.
ORO.FC.202(b) ‘Single-pilot operations under IFR or at night’ requires that pilot recurrent checks be conducted “in an environment representative of the operation”. AAIB say the UK CAA‘s interpretation is that operators undertaking night operations would therefore include night flying in their checks. This was not the operator’s interpretation, perhaps not unreasonably because ORO.FC.202(e) for helicopters, unlike (c) and (d) for aeroplanes, goes on to makes reference only to IFR, not night, requirements.
Although not a causal factor, AAIB note that the helicopter was above the Flight Manual MTOW of 3,175 kg when it took off on the accident flight (being at an estimated 3,237 kg) and indeed on departure from Lisvane that morning (3,221 kg). Using the pilot’s tablet-based Weight & Balance application or completing the sector record page load sheet would have been a barrier to prevent this (though they found errors in other sector record page calculations). The AAIB found the software had not been accessed and load sheets were not completed (an omission they found for other NCO flights).
A review conducted by the operator, of actual vs assumed fuel consumption rates for the AW109SP, revealed that the assumed figure of 240 kg/hr for planning purposes was overly pessimistic and that 220 kg/hr was more representative. They considered that this pessimistic planning consumption rate would have contributed, in part, to the helicopter arriving at destinations with more fuel than anticipated.
This shows how conservatism to minimise one risk (fuel exhaustion) can worsen another.
On survivability:
Of the five passengers on board, four remembered not fastening their seatbelts prior to departure, it was not conclusively determined whether the fifth passenger had fastened theirs. One passenger ascribed the reason for not wearing their seatbelt to the dim lighting in the rear cabin making it difficult to locate ‘the correct belts with the necessary attachments.’ Another passenger did not fasten their seatbelt because others had not been wearing theirs on the morning flight so he chose not to for the return journey.
The absence of a passenger safety briefing clearly did not help, especially as AAIB emphasise:
In helicopters with seating and cabin configurations like G-RAYN’s, once pilots are in their seats, it is not possible for them to visually check the security of their passengers’ seatbelts/harnesses.
The AAIB Safety Investigation – The Tasking, The Helicopter Landing Site Directory & CAT vs NCO Procedures
G-RAYN’s tasking for the 1 November series of flights was generated in response to the helicopter owner’s request for return flights for five passengers between Lisvane and LEA2.
The operator’s ground operations staff followed their normal processes, using their planning tool to validate task feasibility before accepting the request. The OMA [Ops Manual Part A – General] required planners to consider day/night implications and the suitability of landing sites “during the quotation process”.
The operator’s CLSD lists pre-approved Helicopter Landing Sites (HLSs).
A standard CLSD entry would include site details, such as contact and navigational information, as well as mapping and imagery of the landing area. The final page of a CLSD entry is titled “Area Survey (If Applicable)” and includes a table on which the nature, location and height of relevant surveyed obstacles can be listed.
Sites are classified as ‘Surveyed’, ‘Measured’ or ‘Estimated’ in this CLSD. The OMA directs that HLS “should” be surveyed where “time permits”. AAIB notes too that the OMA explains that “the Company has a duty of care to both the crew and the passengers to pre-survey sites prior to use whenever operationally possible”. Measured and Estimated entries exist to allow a degree of operational flexibility, however the categories have different operating restrictions:
Surveyed sites can be used at night subject to certain caveats, but Measured and Estimated HLS ‘may be used by Day only.’
Both LEA2 and Lisvane were Estimated HLSs and therefore, night operations were by default not permitted. However, the CLSD incorrectly showed Lisvane as approved day & night. It also noted the site had lights (but they were noted as “untested”).
A possible reason for the erroneous classification is that had been surveyed for night operations in January 2017 (though the AAIB do not discuss the results of the survey). However, the Lisvane site is smaller than the 4D size (110 m x 60 m) required by the OMA for night operation of an AW109SP anyway.
The departure from LEA2 was scheduled for 1630 hrs, 15 minutes before sunset. A departure from LEA2 before 1715 hrs would have been classed as a daytime takeoff, and thereby compliant with the OMA day-only restriction on Estimated HLSs.
However:
The evening arrival and departure at Lisvane were planned to occur at night.
The helicopter’s owner did inform the pilot that he had turned on the lights at Lisvane remotely.
The tasking documentation generated for the pilot did not include sunset times, neither did it outline any contingency planning considerations for a delayed departure from LEA2.
While the pilot was aware of the sunset time at LEA2, he was under the misapprehension that the OMA allowed him to depart from LEA2 at night because he was operating a nonrevenue, private flight. The OMA specifically stated that no deviation from CAT criteria could be applied to night HLS operations, regardless of flight category.
The investigation heard that, culturally within the industry, NCO operations for helicopter owners in their own aircraft were often referred to as ‘private’ flights; a description used before the category NCO was adopted by regulators to encompass such activity.
This legacy terminology contributed to the pilot’s misunderstanding that, being a ‘private’ flight, he could choose to apply commander’s discretion regarding all additional limitations contained within the OMA, provided he complied with the higher-level regulations of 965/2012.
Believing he could waive the day-only restriction, as the scheduled 1630 hrs departure time approached, the pilot saw no need to hurry the passengers. They did not apply pressure on him to delay the flight.
The AAIB Safety Investigation – Threat and Error Management (TEM) & Safety Management System (SMS)
AMC2 ORO.FC.115 sets out the application of Crew Resource Management (CRM) training to single pilot operations. TEM is included within the ‘general principles’ of the training.
The pilot identified weather and delays as holistic threats for the flight from LEA2 to Lisvane. However, AAIB concluded that how TEM could be used to best effect “was not fully appreciated across the organisation”. Specifically the principle of TEM being a “flight phase by flight phase, tactical strategy, focused on anticipating potential immediate threats to safe operation”.
For the accident flight takeoff, significant threats were the degraded visual environment coupled with a lack of HLS lighting, the presence of trees behind and relatively close to the helicopter, and the westerly wind blowing toward the trees. These combined threats gave rise to the potential error of an inaccurate hover leading to reduced separation from the treeline. The investigation considered that had the pilot been habituated to employing TEM in a more focused way he might have been more effective in identifying and proactively mitigating the takeoff threats.
AAIB explain (with our emphasis added):
The risk of night off-airfield landings had been identified as one of the operator’s top risks in their SMS [Safety Management System]. There was no explicit mention of the risks associated with night off-airfield takeoffs but in many regards the risks could be directly read across.
AAIB Conclusions
Among the highlights of the AAIB conclusions where that:
The accident resulted from the undetected rearward transition of the helicopter into a stand of trees during a planned vertical departure at night from an unlit HLS.
….several barriers that were either breached or not present which might have prevented this accident.
Contradictory and potentially confusing [landing site directory] entries and differing requirements for CAT and non-revenue flights, combined with colloquial legacy terminology, offered an opportunity for misinterpretation over the applicability of the OMA restrictions at the HLSs being used on the day.
Opportunities were also missed during the planning process to anticipate and develop proactive mitigation strategies for delays to the published flight schedule.
The pilot’s focus on delivering the expected service to the clients, despite the challenges posed by a night departure from an unlit site, was indicative of an insidious acclimatisation to risk engendered by long term exposure to the nature of commercial and corporate charter operations.
Acclimatisation to risk is not the sole purview of pilots. For owners and frequent flyer passengers, or those focused on time pressures, it is tempting to see safety briefings and seatbelts as an unnecessary encumbrance. A shared understanding…is key to expectation management in this regard.
Effective TEM could have provided an additional safety barrier for the accident flight.
Safety Actions
The AAIB report that the operator took the following safety actions:
- Amended their Operations Manual, flight documentation, and aircraft technical log sector record pages, to provide greater clarity on who, operator or owner, holds the duty of care and regulatory compliance oversight responsibility for the flight, or series of flights, being undertaken.
- Issued additional instructions to their pilots regarding the process for updating company landing site directory entries and are working with the planning tool developer to align the directory management protocols and templates to their requirements.
- Reminded pilots that, irrespective of a passenger’s previous flying experience or status, safety briefings and a check of seatbelt/harness security must be carried out for every flight.
- Issued an internal Flying Staff Instruction to remind all pilots that the load sheet section of the technical log sector record page must be completed for every sector on all flights.
- They also amended the default weight and balance configuration in the pilot’s software planning application and undertook a review of representative fuel burn rates to be used for flight planning purposes.
- Developed a new Integrated Management System to improve operator processes for the management of hazards. This included a new risk assessment for off-airfield night operations that explicitly covered both night landings and night takeoffs.
- Issued a Flying Staff Instruction in November 2022 to re-iterate the requirements for night off-airfield operations.
- Procured deployable lighting sets for use on flights where there was an identifiable risk of an unscheduled night takeoff resulting from a delay to the planned programme.
- Instigated an annual night flying training programme for all its onshore charter pilots (employees and contractors). The programme’s syllabus specifies theoretical training on night procedures and site surveys as well as a flying element to include night takeoffs and landings using a NATO-T lighting array. The first iteration of this training programme was conducted in November 2022.
- Added landing site risk as an additional criterion in the OM pre-flight risk assessment tool, with night off-airfield operations attracting the highest risk factor loading.
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:
- NTSB Investigation into AW139 Bahamas Night Take Off Accident
- HEMS Black Hole Accident: “Organisational, Regulatory and Oversight Deficiencies”
- Fatal Night-time UK AW139 Accident Highlights Business Aviation Safety Lessons
- Fatal Helicopter / Crane Collision – London Jan 2013
- Grey Charter in French Guiana: IIMC and LOC-I
- A Short Flight to Disaster: A109 Mountain CFIT in Marginal Weather
- HEMS AW109S Collided With Radio Mast During Night Flight
- Visual Illusions, a Non Standard Approach and Cockpit Gradient: Business Jet Accident at Aarhus
- Italian HEMS AW139 Inadvertent IMC Accident
- A Try and See Catastrophe: R44 Accident in Norway in Bad Weather
- Plan Continuation Bias & IIMC in Kenyan Police AW119 Accident
- Regulator Missed the Chance to Intervene Before Fatal Tour Accident say TAIC
- CFIT Gangnam Style – Korean S-76C++ and Decision Making
- Regulatory oversight of New Zealand helicopter operators was challenged after a 2015 accident
- Execuflight Hawker 700 N237WR Akron Accident: Casual Compliance
- Erratic Flight in Marginal Visibility over New York Ends in Tragedy
- Black Hawk Scud Running in Tennessee: IIMC & CFIT
- North Sea Helicopter Struck Sea After Loss of Control on Approach During Night Shuttling (S-76A G-BHYB 1983)
- Blinded by Light, Spanish Customs AS365 Crashed During Night-time Hot Pursuit
See also: EHEST Leaflet HE 3 Helicopter Off Airfield Landing Sites Operations
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