Description

On 10 April 2018, in night normal visibility conditions, a Boeing 737-800 being operated by Gol on a scheduled domestic passenger flight from Brasilia to São Luís with 160 persons on board began takeoff from runway 11L in accordance with its clearance, but as it approached rotation, the crew saw another aircraft - an Embraer 110 being operated by the Brazilian Air Force on a non-scheduled passenger flight from Santa Cruz to Brasilia - that had just landed on the same runway ahead and were only just able to overfly it.

Investigation

A Serious Incident Investigation was carried out by the Aeronautical Accident Investigation and Prevention Centre (CENIPA - Centro de Investigação e Prevenção de Acidentes Aeronáuticos).

It was noted that the Boeing 737-800 Captain had a total of 19,700 hours flying experience of which 7,734 hours were on type and its First Officer had a total of 9,100 hours flying experience of which 7,655 hours were on type. The Captain of the Embraer 110, who was acting as PF for the sector had a total of 479 hours flying experience of which 347 hours were on type and its First Officer had a total of 367 hours flying experience of which 228 hours were on type. The TWR Controller in position at the time of the conflict had six years’ experience and was also a qualified On-the-Job-Training Instructor (OJTI) although he was not acting in that capacity at the time of the investigated event. The GND Controller in position at the time of the conflict had four years’ experience in that role.

It was established that the Embraer flight had proceeded normally and prior to beginning descent, the Captain had given his approach and landing briefing which included the information that after the touchdown on runway 11L, he intended to clear the runway via the (RET) taxiway ‘F’. After touchdown following an uneventful flight, he was able to slow the aircraft sufficiently quickly to be able to clear the runway at an earlier exit which was intended primarily as an RET for aircraft landing on the runway in the opposite (29R) direction and had begun to steer the aircraft to the right to prepare to use it. He stated that having looked quickly to the right and seen a sign which he believed identified this exit as taxiway ‘C’ (see the illustration below), he had asked his First Officer to request this exit from TWR but the response to her call to that effect was an instruction to “clear onto Taxiway ‘G’ and call GND”.

The Captain stated that he had therefore decided to continue as per this instruction and the First Officer changed to the GND frequency and made her initial call there whilst the aircraft was still on the runway reporting that they would clear the runway via ‘G’. The GND Controller acknowledged this and cleared the flight to continue to the military apron. However, the Embraer crew then saw that the next exit was signed as ‘F’ and not ‘G’ and the First Officer therefore called GND to request permission to clear at ‘F’ instead of ‘G’.

Runway 11L annotated with the exits mentioned and the position of the military apron. [Reproduced from the Official Report]

The TWR Controller had been in position for approximately 1¼ hours when the investigated event occurred and stated that he had not been expecting a call from the aircraft after landing and when he received one, he considered that the transmission was made rather quickly which had made it difficult to understand. He noted that after a landing at a controlled aerodrome such as Brasilia, the first radio contact is normally initiated by TWR rather than an aircraft which has just landed. He stated that based on his experience, the message he received was a "ground controlled" matter and so he had continued with his plan to have the aircraft leave the runway on taxiway ‘G’) and call the GND frequency. He had then turned his attention to the 737 awaiting takeoff and, having “made a brief visual scan without seeing the just-landed aircraft, he concluded that it had cleared the runway, since it had already been very close to taxiway ‘G’”. He remarked when he had issued takeoff clearance to the 737, the identification of aircraft on the runway was, as usual at night, hampered by the number of lights on the aerodrome and that this difficulty was aggravated in the case of aircraft which, like the Embraer involved, were camouflaged and without strobe lights.

The GND Controller commented that based on routine practice, a military transport aircraft such as an Embraer 110 would clear runway 11L on taxiway ‘G’ and then take taxiway H’ to reach the military apron. As he had expected this to happen, he had turned his attention to the control of other aircraft. Only when contacted by the Embraer crew requesting to clear onto taxiway ‘F’, did he realise that it was not on the military apron as he had expected and he had then approved the request.

As the Embraer continued towards taxiway ‘F’, its occupants reported they “suddenly perceived a very intense light coming from outside, accompanied by an extremely loud noise and a strong vibration”. As they looked out, some of the occupants reported having seen the 737 that had just passed over their aircraft whilst it was still on the main runway.

The 737 crew noted that they had been waiting for the Embraer to land before receiving their takeoff clearance and that use of 11L for their takeoff was normal for aircraft leaving the northern part of the terminal. They noted that after the Embraer had landed, TWR had instructed them to line up and wait at the runway threshold. Then, “approximately 1 minute and 15 second later” the same controller had cleared them for takeoff. Just before they reached VR, their landing lights had illuminated the Embraer ahead still on the runway and the Captain had immediately advanced the thrust levers to TO/GA and begun to rotate and had just managed to overfly the other aircraft. Once airborne, they reported the near miss to TWR.

Discussion

Based on the factual evidence, the Investigation defined seven relevant ‘Latent Conditions’ which had existed at the time of the conflict as follows:

• The Brasilia Control Tower had several "blind spots" which impeded the view of the controllers, one of which was the length of parallel taxiway ‘H’ between taxiways ‘G’ and ‘N’ where an area of trees made it impossible to see smaller aircraft.

The area of trees (arvoredo) which prevented controllers from seeing smaller aircraft on the shaded area of taxiway ‘H’. [Reproduced from the Official Report]

• The apron lighting on the aircraft parking gates along the north (and south) pier of the passenger terminal obscured the view from the Control Tower at night of the part of the runway adjacent to the trees in the illustration above.
• The Embraer had a camouflaged paint scheme which made it difficult to see at night.
• The Embraer had no strobes, only red anti-collision lights which were not readily visible except at close range.
• The runway profile did not allow an aircraft aligned on the threshold of runway 11L to view a small aircraft on the runway ahead if that aircraft was in a position close to taxiway ‘F’.
• The phraseology used by the Brasilia TWR controllers did not link the frequency change to GND for landing aircraft to being clear of the runway.
• The first two taxiway intersections after the threshold of runway 11L had very similar letter designations which could be confused visually, depending on the viewing conditions, namely ‘C’ and ‘G’.

The absence of a Surface Movement Radar which could provide aircraft position information to controllers was also noted as was the absence from the aerodrome chart of any ‘hot spot’ designation of controller visual blind spots to alert pilots to the existence of this problem. It also proved impossible to identify any regulations that clearly specified when pilots should change frequency from TWR to GND after landing.

It was considered that the evidence available indicated that neither Embraer pilot had been sufficiently familiar with the exit options for their landing runway. A lack of real-time monitoring of the aerodrome chart by the First Officer “may have contributed to an incorrect perception of the aircraft position on the ground after landing” and thereby to her lack of independently informed assistance to the Captain in respect of runway exit identification.

Actual Contributory Factors were, in summary, identified as follows:

• Attention - The TWR Controller’s working environment led him to expect that aircraft would follow instructions given even if this could not be directly monitored and the GND Controller did not seek to establish the position of the Embraer when it first made contact on his frequency.
• Communication - the TWR Controller’s failure to respond by requesting repetition when he did not understand the first call from the Embraer after landing and instead issuing a clearance which he assumed would be expected given the Embraer’s actual position. Also the GND Controller’s non-assimilation of the verbal (future) time used by the Embraer First Officer.
• Controller Physical Working Conditions - impediments to the TWR Controller’s performance at night relating to visual controlling.
• Inadequate TWR/GND controller coordination - in relation to the actual position of the Embraer after landing.
• The absence of ATS Control Ability - ATS procedures which could have identified the possibility that an aircraft was on the runway before the 737 takeoff clearance was issued were not exhausted.
• Airport Infrastructure - the unmitigated interference of airport infrastructure with the TWR Controller’s ability to perform their duties.
• Clearance Limit Exceedance by the Embraer crew - the aircraft (involuntarily) failed to follow its acknowledged runway exit clearance.
• Perception contrary to reality - the similarity between the letters ‘C’ and ‘G’ as exit identifiers aggravated by the night operations contributed to the Embraer Captain’s misidentification; the TWR controller's perception of reality was compromised by his assumption that the crew would comply with their clearance and his expectation that the runway would therefore be clear.

Potential Contributory Factors were also identified, in summary, as follows:

• The TWR controller’s non-use of an available procedure - to only change frequency to GND when clear of the runway - even though this was not a required procedure.
• The TWR controller’s insufficiently definitive use of phraseology - when instructing the Embraer crew to change to the GND frequency after landing given the existence of an exemplar wording in guidance on controller phraseology.
• The inadequate exchange of controller information - between TWR and GND about the Embraer aircraft after its touchdown.
• The Embraer First Officer’s apparent unfamiliarity - with night operations at the airport.
• The Authority Gradient on the Embraer flight deck - the First Officer’s disinclination to question the Captain’s instructions possibly because of her low experience relative to his.
• The absence of a regulatory requirement defining the position where an aircraft should change frequency from TWR to GND after landing.

Safety Action taken by the Military Authorities as a result of the investigated event was noted as the issue of instruction that all Operational Manuals must include text stating that after landing, crews may only change frequency from TWR to GND after clearing the active runway.

Nine Safety Recommendations were made as a result of the Investigation as follows:

• that the Brazil National Civil Aviation Agency (ANAC) acts, together with airport operator INFRAMERICA, in order to make sure that the airport operator adopts measures in relation to the lighting structure of the aprons (North Pier and South Pier), in order to avoid the light coming from the respective spotlights interfering negatively in the line of sight of the TWR controllers. [IG-065/CENIPA/2018 - 01]
• that the Brazil National Civil Aviation Agency (ANAC) works together with airport operator INFRAMERICA and the Air Space Control Department (DECEA) so that cameras for the exclusive use of ATC are installed in the Brasilia International Aerodrome in order to guarantee the visualisation and control of all blind spots at that aerodrome. [IG-065/CENIPA/2018 - 02]
• that the Brazil National Civil Aviation Agency (ANAC) works together with airport operator INFRAMERICA and the Air Space Control Department (DECEA), in order to evaluate the relevance of modifying one or both of the letters of the "C" (Charlie) and "G" (Golf) taxiways of the Brasilia International Aerodrome, so as to avoid confusion or misunderstanding on the part of the crews operating at that aerodrome. [IG-065/CENIPA/2018 - 03]
• that the Brazil National Civil Aviation Agency (ANAC) works together with airport operator INFRAMERICA and the Air Space Control Department (DECEA), in order to evaluate the pertinence of the inclusion of hot spots on the Brasilia International Aerodrome Chart, in order to alert the pilots operating at that aerodrome regarding the existence of blind spots in the manoeuvring area. [IG-065/CENIPA/2018 - 04]
• that the Airspace Control Department (DECEA) analyse the pertinence of establishing, with clarity and in standard, the moment or position in which, after landing, the crew of an aircraft should change frequency from the Tower Control to Ground Control. [IG-065/CENIPA/2018 - 05]
• that the Airspace Control Department (DECEA) alert Brazilian air traffic controllers about the importance of using standard phraseology contained in the applicable procedures (MCA 100-16), notably in what refers to the item (3.4.3.4) on instructions after landing, where an example of correct message is presented. [IG-065/CENIPA/2018 - 06]
• that the Airspace Control Department (DECEA) alert Brazilian air traffic controllers about the importance of using the phraseology provided in (the applicable guidance) item 6.14.6.4 of ICA 100-37/2017, which states that, when necessary or desirable, a controller may instruct a crew to report immediately once their aircraft has cleared the runway in use. [IG-065/CENIPA/2018 - 07]
• that the Airspace Control Department (DECEA) analyse the pertinence of establishing an Operational Model that clearly defines the procedures to be adopted by the air traffic controllers of the different positions of the Brasília International Aerodrome Control Tower in relation to the coordination of traffic when they are passing through the blind spots of the aerodrome. [IG-065/CENIPA/2018 - 08]
• that the Airspace Control Department (DECEA) evaluate the viability of implementing a Surface Movement Radar at Brasilia International Aerodrome, in order to mitigate the risks of runway incursion, due to the various blind spots on the aerodrome. [IG-065/CENIPA/2018 - 09]

The Final Report was completed on 18 December 2020 and published online in both an English translation and in the definitive Portuguese language on 2 January 2021.

Related Articles

• Runway Incursion
• Conflict Detection
• Controller Detection of Manoeuvring Area Conflicts – Guidance for Controllers
• Controller Detection of Manoeuvring Area Conflicts – Safety Barriers
• Runway Incursion and Airport Design
• ATC Expectation Bias
• Perception in ATC