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BN2P / B763, vicinity Kagoshima Japan, 2015

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Summary
On 10 October 2015, a Britten-Norman BN2 instructed to join final behind a Boeing 767 instead joined in front of it which obliged the 767 crew to make a go around. The Investigation was unable to establish why the BN2 pilot failed to follow their conditional clearance but noted that the 'follow' clearance given onto final approach had not been accompanied by a sequence number, and when giving the aircraft type to be followed so that its sighting could be reported, the controller had not challenged the incomplete readback or repeated the aircraft type when subsequently issuing the clearance.
Event Details
When October 2015
Actual or Potential
Event Type
Air-Ground Communication, Human Factors, Loss of Separation
Day/Night Day
Flight Conditions VMC
Flight Details
Aircraft BRITTEN-NORMAN BN-2 Islander
Operator New Japan Aviation
Domicile
Type of Flight Not Recorded
Take off Commenced Yes
Flight Airborne Yes
Flight Completed Yes
Flight Phase Descent
ENR / APR
Flight Details
Aircraft BOEING 767-300ER
Operator japan Airlines
Domicile Japan
Type of Flight Public Transport (Passenger)
Origin Tokyo Haneda International Airport
Intended Destination Kagoshima
Take off Commenced Yes
Flight Airborne Yes
Flight Completed Yes
Flight Phase Descent
ENR / APR
Location - Airport
Airport vicinity Kagoshima
AGC
Tag(s) Phraseology
LOS
Tag(s) Accepted ATC Clearance not followed,
Required Separation not maintained
Outcome
Damage or injury No
Causal Factor Group(s)
Group(s) Aircraft Operation,
Air Traffic Management
Safety Recommendation(s)
Group(s) None Made
Investigation Type
Type Independent

Description

On 10 October 2015, a Boeing 767-300 (JA8364) being operated by Japan Airlines on a scheduled domestic passenger flight from Tokyo Haneda to Kagoshima as JA8364 and on approach at its destination came into close proximity in day VMC to a Britten-Norman BN-2B-20 (JA80CT) being operated by New Japan Aviation which was flying a single left hand circuit and which was flown to the final approach ahead of it. A risk of collision was avoided by the 767 abandoning its approach and making a go around as ATC directed the BN2 to turn away from final approach and remain level.

Investigation

An Investigation was carried out by the Japan Transport Safety Board. Relevant recorded data was available from the 767 FDR and ATC radar. It was noted that although an altitude encoding transponder was installed on the BN2, it was not providing altitude information. It was noted that the 767 First Officer had been PF and that the locally-based BN2 was being flown by a single pilot accompanied by an engineer as passenger. The weather conditions were benign and the reported visibility was more than 10km.

It was established that the controller's planned landing sequence was a DHC8, the 767, the BN2 holding on the left hand downwind leg (which had been told to expect about 10 minutes there) and finally a Robinson R22 helicopter which was holding near the end of the right hand downwind leg as illustrated in the diagram below.

The relative positions of the 767 (aircraft A) and the BN2 (aircraft B) when the BN2 reported "Final Traffic in sight" to ATC. [Reproduced from the Official Report]

Three minutes after its take-off on a one-circuit flight, the BN2 was instructed to hold on the (left) downwind leg and after a further three minutes was advised that about 10 minutes holding could be expected and that traffic to be followed on final was a 767 with 13nm to run. The 767 was then given clearance to land after the DHC8 and the BN2 was advised that the traffic to be followed was now at 9nm and to report it in sight. No sequence number was given. Less than 40 seconds later, the BN2 pilot "sighted a DHC-8 flying on the final approach path about 1 nm from the threshold of Runway 34, assumed it to be the relevant preceding aircraft, and reported 'Final traffic in sight." On hearing this, the controller assumed that the pilot had sighted the 767 and instructed the BN2 to “follow the traffic”, which the pilot read back and then proceeded to final approach without being noticed by the 767 crew.

Soon afterwards, another controller also in the TWR control cabin noticed the BN2 on base leg and about to turn onto final and asked whether it might turn in front of the 767 but as the duty controller assumed that the BN2 was following the 767 as instructed, he turned his attention first to an R22 helicopter which he planned to bring on after the BN2 and by the time he looked out at final approach he saw that the BN2 "had entered the final approach" and was about to tell it to go around when the 767 called saying they had traffic ahead. The controller then instructed the BN2 to turn left and maintain altitude.

The 767 Captain reported that he had first observed the BN2 as a TCAS proximate traffic target with no altitude information and had subsequently located it visually "near the beginning of the base leg" and informed his First Officer. Further down the approach, the crew saw the BN2, which had not seen the 767, cut in front and the Captain made his call to ATC. As he was considering how to respond to the situation having heard the instruction to the BN2 to remain level and turn left away from final approach, he reported having concluded that it was necessary to perform a go around and as he instructed the First Officer to do so the First Officer came to the same conclusion and called accordingly and commenced it. Sight of the BN2 was temporarily lost but the crew were reassured by the knowledge that it would be turning left and continued with a standard go around track straight ahead. As the 767 climbed, the BN2 pilot noticed it for the first time to his right.

The Investigation discovered that a number of TWR controllers at Kagoshima had previous experience of using conditional clearances for aircraft to take their place in a sequence on final approach where the aircraft had joined ahead of the position it had been given despite the controller using the prescribed 'follow' instructions which had clearly identified the aircraft type to be followed.

It was concluded that since there is little similarity between a DHC8 and a 767, it must be presumed that the BN2 pilot "misunderstood" the sighted DHC-8 to be the aircraft he was to follow because "he did not correctly understand the information on the type and location of the notified preceding aircraft provided" by the controller. It was considered possible that a number of factors may have contributed to this:

  • based on his past experience, the BN2 Pilot was convinced that, when instructed to “FOLLOW”, there would only be one preceding aircraft
  • he was not provided with information on the landing sequence number
  • he continued to hold without any strong awareness because he had been informed of the holding time of about 10 minutes, and while assuming that the next instruction and others would not come for a while, he received information on the relevant aircraft about three minutes after the holding instruction, and moreover at a significant distance of 13 miles
  • an event that had occurred in the morning of that day had impacted his attentiveness and obstructed his concentration on the flight.

. The Investigation determined that the Probable Cause of the Serious Incident was that "the BN2 Pilot mistook the DHC-8 that was flying in front of the 767 as the relevant preceding aircraft and as a result proceeded to final approach after the DHC-8 and came into proximity with the 767". It was further considered probable that the BN2 Pilot had mis-identified the relevant preceding aircraft because they "did not correctly understand the traffic information on the type and location of the relevant preceding aircraft provided by the Tower".

It was also concluded that a Contributory Factor may have been "the fact that the Controller did not inform the BN2 of the landing sequence when issuing the conditional clearance to join finals and used only the qualification “FOLLOW”.

On the basis of FDR data from the 767 and ATC radar recordings, it was considered that the closest proximity between the two aircraft was approximately 10 metres laterally and 250 feet vertically. Given the action taken following the detection of a collision risk, the Investigation considered that the appropriate ICAO AIRPROX risk classification for the conflict was 'B' - Safety Not Assured.

Safety Action taken as a result of the occurrence and known to the Investigation included increased emphasis on the need for Kagoshima controllers to ensure clarity in conditional clearances and to seek to monitor clearance compliance as much as possible and for pilots of New Japan Aviation to communicate clearly and unambiguously with ATC in respect of visual acquisition of other relevant traffic.

The Final Report was adopted on 2 December 2016 and published on 15 December 2016. No Safety Recommendations were made.

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