S92, northeast of Aberdeen UK, 2018
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|On 23 August 2018, a low experience Sikorsky S92 First Officer undergoing line training made a visual transit between two North Sea offshore platforms but completed an approach to the wrong one. The platform radio operator alerted the crew to their error and the helicopter then flew to the correct platform. The Investigation attributed the error primarily to the inadequate performance of both pilots on what should have been a straightforward short visual flight but particularly highlighted the apparent failure of the Training Captain to fully recognise the challenges of the flight involved when training and acting as Pilot Monitoring.|
|Actual or Potential
|Human Factors, Runway Incursion|
|Type of Flight||Public Transport (Non Revenue)|
|Take off Commenced||Yes|
|Flight Phase||Missed Approach|
|Approx.||on approach to Brae Bravo platform|
|Tag(s)||Flight Crew Training,|
Approach to Wrong Airport,
Procedural non compliance,
Ineffective Monitoring - SIC as PF
|Damage or injury||No|
|Causal Factor Group(s)|
On 23 August 2018, a Sikorsky S92A (G-CKXL) being operated by Bristow Helicopters on a passenger flight between the East Brae platform and the nearby Brae Alpha platform in day VMC and with pilot line training in progress inadvertently made an approach to the Brae Bravo platform where the radio operator advised the crew of their error. The flight was then continued to the correct destination without further event.
An Investigation was carried out by the Aircraft Accident Investigation Branch (UK) (AAIB). It was established that the flight involved had been the third sector of a four sector sequence flown by the same crew beginning and ending at Aberdeen and involving successive stops at the three platforms of the Brae field in the northern North Sea, approximately 150nm northeast of Aberdeen in the sequence Brae Bravo, East Brae and Brae Alpha. The illustration below is annotated with the distances and bearings between the three platforms.
It was noted that the 56 year-old Captain, who had been PM for the flight involved, had a total of 10,968 flying hours of which 2,453 hours were on type and was experienced in offshore operations. The ab-initio First Officer had recently obtained his S92 type rating and was on his first day of line training.
It was established that a detailed brief had preceded the departure from Aberdeen which included consulting the Helideck Directory (HD) in respect of all three offshore destinations. The HD is the standard reference for UK North Sea operations and includes full information on all offshore platform helidecks and the approaches to them supported by pictorial representations of each platform and its helideck.
The pilots reported having assessed that “all three landings required a similar approach path, routing around the flare-stacks on the northern side of the platforms and turning left to land on the helideck in a southerly direction, whilst accepting light cross-winds”. This meant that all helideck landings would have to flown from the left seat and the Training Captain decided that he would act as PM for all sectors. Prior to taxiing at Aberdeen, the crew entered the complete route into the FMS routing. The flight to Brae Bravo was uneventful but on the second inter-platform sector between Brae Bravo and East Brae, the Captain had taken over took as PF when the First Officer experienced handling difficulties in the hover over the destination helideck.
During the turnround, the Captain debriefed the arrival and the routing to the next destination “and noted that the needles slaved to the FMS were pointing in the expected direction”. As the First Officer turned right after a southerly takeoff, the Captain reported that he “saw the platform as expected” and noted that “the FMS needles pointed in the expected direction” and mentally noted “there’s the rig and the flare-stack to fly around”, as had been discussed during pre-flight planning. However, he had actually visually acquired the Brae Bravo platform which was about half the distance from East Brae to the intended destination Brae Alpha. The First Officer continued the flight manually and briefed the approach. The Captain reported having used the available time to coach the First Officer on the handling of the approach and carrying out the ‘Final Checks’ applicable to short inter-platform flights with the exception of the final two - arming the floats and confirming the deck name - so as to minimise interruption during the final stages of the approach.
The First Officer flew around the single flare-stack (see the HD plate below for Brae Bravo) to the north, turned left onto the approach and flew to the hover over the helideck. Although the floats were armed during the final stages of the approach, the Captain, who was unable to see the helideck throughout the final stages of the approach, did not read the deck name or prompt the First Officer to confirm it. On being advised by the platform radio operator that they had made an approach to Brae Bravo, the crew acknowledged, obtained confirmation that they could proceed and set off for Brae Alpha and subsequently arrived there without further problems.
The Investigation noted that the HD information was supplemented in electronic form by an EFB (iPad mini) loaded with proprietary offshore platform information equivalent to that contained in the hard copy HD which, at the time of the investigated event, was also available in hard copy form.
A comparison of the summary charts for Brae Bravo and Brae Alpha, reproduced side by side below, shows that, although they have similar helideck locations on the south-southwest corner of the platform, there are a number of differences, two of which should be immediately obvious. The Brae Alpha platform has two flare-stacks which rise diagonally from the northwest and northeast corners whereas the Brae Bravo platform has a single flare stack protruding horizontally from the lower northwestern side. Also, the Brae Alpha platform has two vertical derricks on the same side of the platform as its flare-stacks whereas the Brae Bravo platform has only a single vertical derrick.
Operator SOPs were found to address the known risk of ‘Wrong Deck Landings’ (WDL) and it was clear that much of this guidance had been ignored prior to and during the flight from East Brae to the ‘Wrong Deck Approach’ (WDA) to Brae Bravo.
The Investigation noted that a number of the controls aimed at both prevention and subsequent detection of a WDL or WDA had been ineffective:
- A shared appreciation of the potential for incorrect platform selection during pre-flight planning by using the HD plates to establish key identifying features and differences between platforms.
- Neither pilot maintained adequate situational awareness whilst within the Brae Field and neither made appropriate use of the GPS navigation display which could have alerted them to the incorrect selection of the destination platform. In particular, no reference was made to the FMS displays of range to the platform or the routing to it, the radar remained in standby and no use was made of the ‘Navblue’ charts available on flight deck EFB during the pre departure brief at East Brae.
- The helideck crew on Brae Alpha were unable to detect the WDA being made to Brae Bravo at the time ‘deck availability’ was requested and approved.
- Neither pilot detected and recognised the WDA by reading the platform name as required by SOPs.
It was noted that all that had prevented the WDA from becoming a WDL was the vigilance of the Brae Bravo radio operator - the platform helideck crew would have completed their duties with the earlier departure of the helicopter and the radio operator’s role was primarily to monitor radio calls not to visually identify helicopter traffic.
A number of factors which led to the various prevention controls being ineffective were identified and included the following:
- Platform Alignment - the alignment of the Brae Bravo and Brae Alpha platforms relative to the routing from East Brae was broadly similar with the nearest platform being the most obvious and may also have contributed to Brae Alpha being obscured by Brae Bravo.
- Platform Characteristics - the three platforms in the Brae field shared “an overall visual similarity in configuration and infrastructure” which resulted in the Brae Bravo platform displaying ‘decoy characteristics’. Although each platform does have distinctive differences, when approached from certain directions, these differences are unlikely to be sufficiently obvious to override the existence of any expectation and confirmation bias during a high workload environment.
- The Helicopter Directory (HD) - the content of the HD is only reviewed every two years and the photographs used are not routinely updated and may therefore present a visual image that is many years old and the direction from which photographs are taken varies.
- The Operator EFB - although the EFB plates did “not differ in quality or in visual imagery” from those in the HD, their use in flight to corroborate correct identification of the platform would have been inappropriate.
- Familiarity – The Captain’s perceived sense of familiarity with the Brae Field platforms were considered “likely to have overridden a more detailed scrutiny” of the HD Plates during briefing which could have led to the highlighting of the distinctively different features of the platforms.
- Use of FMS - The pilots ignored the track distance available from the FMS display, which could have alerted them to the incorrect selection of Brae Bravo as the destination.
- Expectation and Confirmation Bias - The Captain’s expectation that the destination platform would be sighted during the initial right turn from the southerly departure set up the conditions for confirmation bias to take hold
- Workload - both the successive short sectors and the fact that this was the inexperienced First Officer’s first day of line training combined to create a high workload for the Captain which was considered to have “led to reduced scrutiny by him when selecting the (incorrect platform) as the destination” and to a focus thereafter on “the more immediate priority of the safe handling of the helicopter to the detriment of other sortie management priorities”.
- Multi-crew environment - during early stage line training with an ab-initio pilot, many of the defences that are derived from operating in a multi-crew environment were undermined or effectively removed.
The Cause of the event was determined to have been “the pilots initially misidentifying and selecting the Brae Bravo platform, instead of the Brae Alpha platform, as the destination and subsequently not detecting this incorrect selection” and noted that “several prevention controls that should have alerted the pilots to the incorrect platform selection and subsequently aided them in identifying (their error had) proved ineffective”.
A number of Contributory Factors were also identified including:
- the inadequate identification by the pilots of the key features and differences of the platforms in the Brae field.
- the decision to fly the short sector manually and to navigate visually, which whilst appropriate for the good in-flight visibility and the stage reached during line training, led to an increased workload for the PM Captain and reduced the attention given to the electronic cues that existed in the flight deck.
- the short sector which provided a very small window of time for the pilots to identify, select and confirm the destination platform with little subsequent opportunity to review.
- the inherent nature of early-stage line training which increased and effectively nullified the protections normally afforded by two-pilot operations.
- the high workload which combined with the overriding influences of expectation and confirmation biases.
Overall, it was concluded that “this event highlights the challenges that exist while flying off-shore, even during benign conditions, during a typical sortie flown in the early stages of line training” and that many of the contributory factors found in the Investigation “have previously been identified as typical factors that contribute to wrong-deck landings”.
Safety Action identified by the aircraft operator as “to be carried out” in relation to ‘shuttle’ operations was noted to have consisted of the following:
- Training to highlight complex requirements of shuttling and need to concentrate on all aspects of SOPs.
- Highlighting the importance of following checklists at appropriate times.
- A review of checklist use during ‘shuttle’ flights.
- Highlighting task management during the pre flight brief for a ‘shuttle’ flight made during line training.
The Final Report of the Investigation was published on 8 August 2019. No Safety Recommendations were made.