Final report dell'incidente
On Jun 19th 2015 South Africa's Civil Aviation Authority (SACAA) released their final report concluding the probable cause of the accident was:
The loss of situational awareness caused the crew to taxi straight ahead on the wrong path, crossing the intersection/junction of Bravo and Mike instead of following Bravo where it turns off to the right and leads to the Category 2 holding point. Following aircraft stand taxilane Mike; they collided with a building on the right-hand side of Mike.
Contributory Factors:
The crew did not conduct a briefing to discuss the cleared route, nor did they refer to the correct taxiway information in chart 10-6. In combination with the ground movement visual aids, this created confusion and loss of situational awareness when taxiing on taxiway Bravo.
The SACAA reported that the crew had expected to taxi to runway 03L via taxiway E and A. However, after having pushed back and requesting taxi, the crew was cleared: "Speedbird 34, taxi Bravo to Cat 2 holding point, Runway 03L." The first officer (51, ATPL, 5,700 hours total, 1,400 hours on type) was handling pilot, the captain (57, ATPL, 20,050 hours total, 12,500 hours on type) pilot monitoring.
The SACAA summarized captain's testimony: "The aircraft remained on what was perceived to be still taxiway Bravo. The taxiway edge lights illuminated in a continuous straight line with no signage indicating the change of the two taxiways Bravo & Mike. Also, some of the green centreline lights on taxiway Bravo were not illuminated in sequence thus leading to a false perception that the aircraft is still on taxiway Bravo. However, during the taxi while going through the before take-off procedure and checklist, after we entered the taxiway Mike, the Co-pilot voiced a concern about the width of the taxiway Mike and proximity of the building on the right side of the taxiway. The Co-pilot could not judge the proximity of the aircraft from the building because of the strong apron background glare."
The SACAA reported, that the bend of taxiway B had been fitted with 15 green taxiway center line lights showing the bend, however, the SACAA stated: "It is important to note that 2 centreline lights installed on the curve/bend of Bravo toward the Category 2 holding point were found unserviceable (not illuminating)."
The SACAA analysed that ATC followed procedures and requirements.
The SACAA analysed: "The CVR download information helped a great deal in drawing up a mental picture of what happened. The information showed that during the flight preparation phase the crew had a briefing in the cockpit which included discussion on pre-flight, taxi and take-off. It is important to note that they talked about the expected taxi route. The crew was expecting to be cleared to “push out tail south, taxiing down taxiway Alfa”. They planned to “turn into taxiway Alfa for a full length taxi and keep going the extra 200 m straight up to the end of Runway 03”. The briefing discussion lasted for ± 7 minutes. During the briefing the crew pointed out the high risk areas (e.g. potential dangers and hazards) which they identified. When reaching the high risk areas, caution was required to avoid the risk of collisions. Throughout the briefing discussion the crew’s mind was set on the expected route using taxiway Alfa. The evidence of this fact can be seen in the Captain asking: “Am I looking at the right thing here, Oh! Alfa is the full length just there” and the Co-pilot’s response was “yes, it morphs into Bravo”."
The SACAA continued analysis stating that the crew had correctly understood the instruction to taxi via taxiway B. However: "After having received the taxi clearance, they did not alter their expectation and review the new route. If they had, they might have foreseen the conditions on taxiway Bravo. They might have discussed the information on the bend (“curve”) to the left near the intersection/junction with Mike. Also, they would have been prepared to look for cues to indicate that they were approaching the bend."
The SACAA analysed that ground surveillance radar confirmed the aircraft joined taxiway B, the taxi speed increased on taxiway B, passing a total of 4 green center line lights on the way towards the bend/intersection with taxiway M. The SACAA analysed that a total of 7 green center line lights did not illuminate, amongst them the two directly at the bend and stated:
The taxiway green centreline lights issue did not just stop there.
More anomalies with the lighting and signage on Bravo were identified in the investigation.
The investigation determined that a total of 7 (distance ± 235 metres) of green centreline lights were not illuminating. From the apron after the curve leading to taxiway Bravo, 5 lights (distance ±180 metres) were not illuminating.
On the curve leading to the Cat 2 holding point, two more lights were out (distance ±45 metres).
Over a distance of ±300 metres to the holding point, no lights were installed.
The total distance not illuminated was ±535 metres.
The total length of Bravo is ±1425 metres, of which ±535 metres was not illuminated – approximately 36.84%.
The investigation determined that the direction information sign on the left side of Bravo (±60 metres from the intersection of taxiway Bravo and taxilane Mike) was not illuminated. This sign consists of a black inscription on a yellow background which is supposed to glowing brightly in the direction of approach to the intersection. It is possible that because it was not illuminated and visible to the crew, they may have not seen it, which means that the sign did not serve its design purpose.
Note: The crew did not do a briefing using both Charts 10-2 and 10-6 together to obtain or familiarise themselves with relevant published information about the expected conditions on taxiway Bravo. They would have been prepared or alerted to look out for the centreline lights on taxiway Bravo and for the direction information sign on the left side indicating the bend of taxiway Bravo. Also, they were not fully prepared for or aware of the conditions of taxiway Bravo, which is why they lost situational awareness later during the taxi.
The SACAA analysed: "According to ICAO requirements, there shall not be 2 adjacent taxiway centre line lights unserviceable. This requirement is also set in the applicable regulations. Therefore ACSA contravened the applicable regulations. The issue of the unserviceable lights was investigated with ACSA and ATNS."
The SACAA analysed:
In the light of the above information about Mike, Mike’s contribution to the confusing situation was identified as the following:
- the name “taxilane”;
- Installation of blue taxiway edge lights;
- blue edge lights switched on (illuminating) at night, even when the “taxilane” was not in use;
- its smaller width compared with taxiway Bravo, but blue edge lights on the right side identifying edge line carries straight on from Bravo to Mike;
- no information signage in vicinity of the intersection of taxiway Bravo and Mike to identify the starting point of Mike;
- the intermediate taxi-holding position marking across Mike just opposite the Bid Air Service building;
- poor visibility of the obstacle (Bid Air Services building) during night-time (no appropriate red or white flashing lights)
The SACAA analysed, that the first officer immediately after crossing the intersection taxiways B and M and missing the bend "asked: “Is it me or does this taxiway feel very narrow?” The assumption is that he was alerted by the taxiway width becoming less (12 metres narrower). Though not supported by evidence, it would appear that the Co-pilot was looking at the position of the blue edge lights (indicating the edge line of the taxiway) on Mike, which helped him gauge the width of the “taxilane” from the cockpit. Despite his concern, the Co-pilot continued straight on."
http://avherald.com/h?article=46d6e18c&opt=0
On Jun 19th 2015 South Africa's Civil Aviation Authority (SACAA) released their final report concluding the probable cause of the accident was:
The loss of situational awareness caused the crew to taxi straight ahead on the wrong path, crossing the intersection/junction of Bravo and Mike instead of following Bravo where it turns off to the right and leads to the Category 2 holding point. Following aircraft stand taxilane Mike; they collided with a building on the right-hand side of Mike.
Contributory Factors:
The crew did not conduct a briefing to discuss the cleared route, nor did they refer to the correct taxiway information in chart 10-6. In combination with the ground movement visual aids, this created confusion and loss of situational awareness when taxiing on taxiway Bravo.
The SACAA reported that the crew had expected to taxi to runway 03L via taxiway E and A. However, after having pushed back and requesting taxi, the crew was cleared: "Speedbird 34, taxi Bravo to Cat 2 holding point, Runway 03L." The first officer (51, ATPL, 5,700 hours total, 1,400 hours on type) was handling pilot, the captain (57, ATPL, 20,050 hours total, 12,500 hours on type) pilot monitoring.
The SACAA summarized captain's testimony: "The aircraft remained on what was perceived to be still taxiway Bravo. The taxiway edge lights illuminated in a continuous straight line with no signage indicating the change of the two taxiways Bravo & Mike. Also, some of the green centreline lights on taxiway Bravo were not illuminated in sequence thus leading to a false perception that the aircraft is still on taxiway Bravo. However, during the taxi while going through the before take-off procedure and checklist, after we entered the taxiway Mike, the Co-pilot voiced a concern about the width of the taxiway Mike and proximity of the building on the right side of the taxiway. The Co-pilot could not judge the proximity of the aircraft from the building because of the strong apron background glare."
The SACAA reported, that the bend of taxiway B had been fitted with 15 green taxiway center line lights showing the bend, however, the SACAA stated: "It is important to note that 2 centreline lights installed on the curve/bend of Bravo toward the Category 2 holding point were found unserviceable (not illuminating)."
The SACAA analysed that ATC followed procedures and requirements.
The SACAA analysed: "The CVR download information helped a great deal in drawing up a mental picture of what happened. The information showed that during the flight preparation phase the crew had a briefing in the cockpit which included discussion on pre-flight, taxi and take-off. It is important to note that they talked about the expected taxi route. The crew was expecting to be cleared to “push out tail south, taxiing down taxiway Alfa”. They planned to “turn into taxiway Alfa for a full length taxi and keep going the extra 200 m straight up to the end of Runway 03”. The briefing discussion lasted for ± 7 minutes. During the briefing the crew pointed out the high risk areas (e.g. potential dangers and hazards) which they identified. When reaching the high risk areas, caution was required to avoid the risk of collisions. Throughout the briefing discussion the crew’s mind was set on the expected route using taxiway Alfa. The evidence of this fact can be seen in the Captain asking: “Am I looking at the right thing here, Oh! Alfa is the full length just there” and the Co-pilot’s response was “yes, it morphs into Bravo”."
The SACAA continued analysis stating that the crew had correctly understood the instruction to taxi via taxiway B. However: "After having received the taxi clearance, they did not alter their expectation and review the new route. If they had, they might have foreseen the conditions on taxiway Bravo. They might have discussed the information on the bend (“curve”) to the left near the intersection/junction with Mike. Also, they would have been prepared to look for cues to indicate that they were approaching the bend."
The SACAA analysed that ground surveillance radar confirmed the aircraft joined taxiway B, the taxi speed increased on taxiway B, passing a total of 4 green center line lights on the way towards the bend/intersection with taxiway M. The SACAA analysed that a total of 7 green center line lights did not illuminate, amongst them the two directly at the bend and stated:
The taxiway green centreline lights issue did not just stop there.
More anomalies with the lighting and signage on Bravo were identified in the investigation.
The investigation determined that a total of 7 (distance ± 235 metres) of green centreline lights were not illuminating. From the apron after the curve leading to taxiway Bravo, 5 lights (distance ±180 metres) were not illuminating.
On the curve leading to the Cat 2 holding point, two more lights were out (distance ±45 metres).
Over a distance of ±300 metres to the holding point, no lights were installed.
The total distance not illuminated was ±535 metres.
The total length of Bravo is ±1425 metres, of which ±535 metres was not illuminated – approximately 36.84%.
The investigation determined that the direction information sign on the left side of Bravo (±60 metres from the intersection of taxiway Bravo and taxilane Mike) was not illuminated. This sign consists of a black inscription on a yellow background which is supposed to glowing brightly in the direction of approach to the intersection. It is possible that because it was not illuminated and visible to the crew, they may have not seen it, which means that the sign did not serve its design purpose.
Note: The crew did not do a briefing using both Charts 10-2 and 10-6 together to obtain or familiarise themselves with relevant published information about the expected conditions on taxiway Bravo. They would have been prepared or alerted to look out for the centreline lights on taxiway Bravo and for the direction information sign on the left side indicating the bend of taxiway Bravo. Also, they were not fully prepared for or aware of the conditions of taxiway Bravo, which is why they lost situational awareness later during the taxi.
The SACAA analysed: "According to ICAO requirements, there shall not be 2 adjacent taxiway centre line lights unserviceable. This requirement is also set in the applicable regulations. Therefore ACSA contravened the applicable regulations. The issue of the unserviceable lights was investigated with ACSA and ATNS."
The SACAA analysed:
In the light of the above information about Mike, Mike’s contribution to the confusing situation was identified as the following:
- the name “taxilane”;
- Installation of blue taxiway edge lights;
- blue edge lights switched on (illuminating) at night, even when the “taxilane” was not in use;
- its smaller width compared with taxiway Bravo, but blue edge lights on the right side identifying edge line carries straight on from Bravo to Mike;
- no information signage in vicinity of the intersection of taxiway Bravo and Mike to identify the starting point of Mike;
- the intermediate taxi-holding position marking across Mike just opposite the Bid Air Service building;
- poor visibility of the obstacle (Bid Air Services building) during night-time (no appropriate red or white flashing lights)
The SACAA analysed, that the first officer immediately after crossing the intersection taxiways B and M and missing the bend "asked: “Is it me or does this taxiway feel very narrow?” The assumption is that he was alerted by the taxiway width becoming less (12 metres narrower). Though not supported by evidence, it would appear that the Co-pilot was looking at the position of the blue edge lights (indicating the edge line of the taxiway) on Mike, which helped him gauge the width of the “taxilane” from the cockpit. Despite his concern, the Co-pilot continued straight on."
http://avherald.com/h?article=46d6e18c&opt=0