B737, Gran Canaria Spain, 2016
B737, Gran Canaria Spain, 2016
On 7 January 2016, a Boeing 737-700 was inadvertently cleared by ATC to take off on a closed runway. The take-off was commenced with a vehicle visible ahead at the runway edge. When ATC realised the situation, a 'stop' instruction was issued and the aircraft did so after travelling approximately 740 metres. Investigation attributed the controller error to lost situational awareness. It also noted prior pilot and controller awareness that the runway used was closed and that the pilots had, on the basis of the take-off clearance crossed a lit red stop bar to enter the runway without explicit permission.
On 7 January 2016, a Boeing 737-700 (D-ABLB) being operated by Germania on a passenger flight (GMI 6129) from Gran Canaria to Friedrichshafen in normal day visibility began take-off from runway 03R in accordance with an ATC clearance but the take-off was subsequently rejected from approximately 60 knots on ATC instructions, the controller having realised that an object was present on the runway. Prior to the event unfolding, both the controller involved and the pilots "knew that runway 03R was closed".
After an unspecified delay in the reporting of the event to the Spanish Commission for the Investigation of Civil Aviation Accidents and Incidents (CIAIAC), an Investigation was commenced. Recorded data from the CVR and FDR were no longer available due to this delay but the aircraft Operator provided relevant data from the QAR and a recording of pertinent ATC communications with the aircraft was available. The Investigation had requested a copy of relevant security camera footage of runway 03R "in order to ascertain the conditions in which the vehicle was working, its position and the movement of the aircraft" but the Airport Operator had "stated that such footage was not available". Weather conditions were not relevant to the occurrence - light winds and good visibility prevailed.
The 36 year-old Captain was a German national who had accumulated a total of 6,550 flying hours which included 1,550 as Captain. Most of his experience - 6,030 hours - had been on the Boeing 737. The 26 year-old First Officer was a Dutch national who had accumulated a total of 1,000 flying hours which included 650 hours on type. Which pilot was acting as PF at the time of the event was not identified. The 38 year-old Controller involved had been a TWR controller since 2008 and at Gran Canaria since 2010. He was also both a supervisor and a supervisory instructor. He had just begun his afternoon shift as TWR Controller and had received a comprehensive position handover from the off-going controller which included the fact that runway 03R was closed.
It was established that the TWR controller had, after clearing the previous departing aircraft to take off from runway 03L, cleared the 737 to "cross 03L and line up and wait on runway 03R". In the absence of a response from the aircraft which the crew reported had been a direct consequence of their "confusion" on hearing that their departure would unexpectedly now be from runway 03R, the controller repeated the instruction which was then acknowledged. About a minute later, the 737 crew observed a lit red stop bar ahead at the runway 03R holding point and queried this with the controller whilst briefly stopping the aircraft. Although responsible for the TWR frequency, the controller was also monitoring the Departure frequency in respect of the recovery of a helicopter using newly modified procedures and a transmission on Departure from the previously-departed aircraft overlapped the beginning of the query made by the 737 so that he only "heard part of the message" they transmitted. He subsequently stated that "he assumed that the crew had made the typical report that they were ready for departure". He therefore "re-authorised the crew to line up and wait on runway 03R" and, two minutes later issued take-off clearance. The 737 crew taxied into position across the lit stop bar and awaited take-off clearance. They reported having been aware of a vehicle ahead and on the right hand edge of the 45 metre-wide runway and stated that it did not have any flashing lights on. When they received take-off clearance two minutes after the (repeated) clearance to line up and wait, the vehicle was still there but "thought there was no collision danger" so they began the take-off. It was noted that since the vehicle concerned was not on the TWR frequency, the crew "did not know the vehicle’s intentions”.
The controller, who had previously not seen the vehicle and had forgotten, despite the prescribed indications of its status being present at his position, that runway 03R was closed and therefore the responsibility of the GND controller, reported subsequently that he "became aware...of the presence of an object on the runway strip at the same time as his colleague in the ground position (and) immediately cancelled the take-off clearance”. At this point, the aircraft was about to pass the vehicle. FDR data showed that when the crew promptly responded to this instruction, the aircraft had a reached groundspeed of just over 60 knots and had travelled approximately 270 metres along the 3,100 metre-long runway. It came to a complete stop 40 seconds later after travelling 740 metres. QAR data were used to make an approximate reconstruction of the path followed by the aircraft during the ultimately rejected take-off (see the illustration below).
It was noted that the closure of runway 03R had been included on the ATIS broadcasts (hence the crew awareness of this) and was promulgated by NOTAM as the case throughout the day.
The Investigation noted that local investigations into the occurrence had been carried out by both the ANSP (ENAIRE) and the airport operator (AENA) and the findings advised. The AENA Report was found to state that "the vehicle had flashing lights and that they were on during the work" in accordance with its regulations, but given that the security camera footage which would have supported this assertion had been stated to the Investigation as "unavailable", it was unclear how this had been demonstrated. ENAIRE stated to the Investigation a Checklist for controller position handover "had been in place since 2015, though its use was not obligatory" and that "on the day of the incident there was no updated copy of the Checklist at the controller positions in use, as it had likely been misplaced".
It was also noted that specific procedures documented in the ENAIRE Operations Manual under 'Specific Unit Procedures' included the following controller actions in respect of closed runways:
- Indicate that the runway is occupied by an obstacle, aircraft or vehicle by placing a strip on the strip holder that specifies the nature of the obstacle. In addition, the strip holder is to be placed across the bay.
- Pay special attention to crew acknowledgments regarding the runway on which they are cleared to operate.
- Visually check, and verify using radar if needed, that the cleared aircraft is proceeding to the runway in use.
- A closed runway shall remain under the control of GND, meaning its use does not have to be coordinated with TWR.
The TWR Supervisor noted that a new procedure for recovering helicopters required to maintain regulatory compliance which had taken effect on the day of the occurrence was more "complex" than the previous procedure and that although the unit had a training simulator, familiarisation with this new procedure had been achieved through a classroom session, the simulator only being used for emergency and contingency plan change training.
The role of the Local Runway Safety Committee (LRSC) in relation to the occurrence was considered. It was found that under a specific Technical Safety Instruction issued by the National Aviation Safety Agency (AESA), the LRSC had "responsibilities" which included "identifying potential safety problems on runways" and "ensuring that the recommendations included in the EAPPRI are implemented". This Technical Instruction also stated that "when the timeline or the urgency does not allow waiting until the next regular meeting", relevant matters will require that additional "extraordinary" meetings shall be held to address them. It also states that the proceedings of all meetings "is to be reflected in the minutes, which must be sent to the interested parties within two weeks" who will have "at least a further two weeks to make comments or request changes".
With this in mind, it was noted that:
- The survey work which would involve regular closure of runway 03R was not discussed at the regular LRSC meeting held on 1 December 2015. However, this meeting did decide, according to the minutes, that the introduction of lighted cones at the thresholds of temporarily closed runways would help to avoid runway incursions and that this measure "would be immediately implemented". The minutes of this meeting were approved on 15 January 2016, eight days after the investigated event had occurred.
- A meeting to discuss the work which would involve regular closure of runway 03R was held on 21 December 2015 but this was not an LRSC meeting and was not open to all members of the LRSC. The plan to place cones temporarily whilst a runway was closed as agreed during the LRSC meeting held on 1 December was "not discussed".
In respect of regulatory guidance on the subject of lit red stop bars across taxiways, it was noted that although ICAO (Annex 2, Doc 4444 and Doc 9870), European SERA ATS procedures and the EAPPRI all state that aircraft should not be taxied across such stop bars unless "contingency procedures" are in place, there is no definition of the what such procedures might be, only a single example, the use of a follow-me vehicle. No reference was made to any corresponding aircraft operating documentation. It was considered that the Investigation had "revealed a lack of common procedures or phraseology that allow crews to clearly identify if said measures are in effect" which "could have created doubts in the crew of the Germania aircraft, since after informing ATC that there was an illuminated stop bar and being cleared once more to line up on the runway, they might have assumed that said contingency measures were in place".
The existence at the time of completion of the Investigation of a relevant EASA Notice of Proposed Amendment (NPA) was noted, which although "subject to change until it goes into effect" provided the following guidelines in respect of "contingency measures to be used when the lights on a stop bar cannot be turned off":
- Disconnect the power supply from the affected stop bar.
- Dim the lights on the affected stop bar.
- Provide a vehicle to drive the aircraft across the stop bar.
The Cause of the event was formally stated as "the controller’s loss of situational awareness, as he instructed the crew of (the Boeing 737) to enter and then take off from runway 03R, despite (them) knowing that it was closed".
Five Contributing Factors were identified as:
- The controller did not detect his mistake despite the presence of visual aids in the Tower indicating that the runway was closed. He also did not see the car in the runway 03R strip, though this may have been caused, as per the statement from the crew and the controller, by the fact that the car did not have its flashing lights on.
- The controller only partially heard a report from the crew notifying that the stop bar was illuminated, but he did not ask for the message to be repeated and again instructed the crew to line up and wait.
- The crew crossed an illuminated stop bar without having information regarding contingency measures in place to specifically allow this. Contributing to this was the fact that the regulation on stop bars and the applicable manuals were not clear or specific.
- The aircraft’s crew started the take-off run despite being in visual contact with the vehicle that was stopped on the runway strip.
- The mitigation measure of placing cones at the threshold of the temporarily closed runway was not in effect because the minutes of the Local Runway Safety Committee meeting, where this measure had been proposed, had not yet been approved.
Safety Action by the ANSP ENAIRE as a result of the event and known to the Investigation was noted as including the following:
- Their internal occurrence investigation had recommended that "if a controller monitoring another frequency became aware of another traffic calling, they should request that the message be repeated to avoid misunderstanding or mistakes". Confirmation of implementation of the recommendation and the means of implementation was not recorded.
- In respect of the alerting of controllers to the fact that a runway is closed, it was decided that an additional strip would be placed on the wind velocity indicator whenever a runway is occupied so that "when a controller clears an aircraft to take off/land, they would look at the wind reading and see that the runway is closed".
Two Safety Recommendations were made as a result of the Investigation as follows:
- that ICAO develop a common procedure or phraseology for the application of contingency measures in the event that a stop bar cannot be turned off such that crews can clearly identify when said contingency measures are in place. [REC 31/2016]
- that ENAIRE should include practical simulator training sessions for its controllers when new procedures are expected to go into effect that involve large operational changes or that greatly increase the workload of controllers. [REC 32/2016]
The Final Report was approved on 31 May 2016 and subsequently made available in English translation.