Emirates B777 Runway Impact During Attempted Go-Around, 3 August 2016, Dubai: Accident Report

Emirates B777 A6-EMW: Runway Impact During Attempted Go-Around, 3 August 2016, Dubai: Accident Report

On 6 February 2020, the Air Accident Investigation Sector (AAIS) of the UAE General Civil Aviation Authority (GCAA) released their safety investigation report into a 3 August 2016 accident.  Emirates Boeing 777-31H A6-EMW, had departed Trivandrum International Airport (VOTV), India for Dubai International Airport (OMDB), the United Arab Emirates, with 282 passengers, 2 flight and 16 cabin crew members aboard.

The Commander’s total flying experience was 7,457 flying hours, including 3,950 hours as a copilot and 1,173 hours as a commander on the B777.  The Copilot’s total flying experience was 7,957 flying hours, including 1,292 as a copilot on the B777.  Both pilots had performed go-around and missed approach exercises during their training and had performed one normal go-around as pilot flying on the B777 each within 4 months prior to this flight.

History of the Flight

AAIS explain that on arrival at Dubai the Aircraft Commander attempted to perform a within-limits tailwind manual landing during forecast moderate windshear.

During the landing on runway 12L at OMDB the Commander, who was the pilot flying, decided to fly a go-around, as he was unable to land the Aircraft within the runway touchdown zone. The go-around decision was based on the perception that the Aircraft would not land due to thermals and not due to a windshear encounter. For this reason, the Commander elected to fly a normal go-around and not the windshear escape maneuver.

The flight crew initiated the flight crew operations manual (FCOM) Go-around and Missed Approach Procedure and the Commander pushed the TO/GA switch. As designed, because the Aircraft had touched down, the TO/GA switches became inhibited and had no effect on the autothrottle (A/T).

The flight crew were not aware a 6 second touch down had occurred.

After becoming airborne during the go-around attempt, the Aircraft climbed to a height of 85 ft radio altitude above the runway surface. The flight crew did not observe that both thrust levers had remained at the idle position and that the engine thrust remained at idle.

The Aircraft quickly sank towards the runway as the airspeed was insufficient to support the climb. As the Aircraft lost height and speed, the Commander initiated the windshear escape maneuver procedure and rapidly advanced both thrust levers. This action was too late to avoid the impact with runway 12L. Eighteen seconds after the initiation of the go-around the Aircraft impacted the runway at 0837:38 UTC and slid on its lower fuselage along the runway surface for approximately 32 seconds covering a distance of approximately 800 meters before coming to rest adjacent to taxiway Mike 13.

a6emw b777 dubai accident sequence

a6emw b777 flight data

The B777 remained intact but ” several fuselage mounted components and the No.2 engine/pylon assembly separated”.

During the evacuation, several passenger door escape slides became unusable.

a6emw b777 doors

Many passengers evacuated the Aircraft taking their carry-on baggage with them.

a6emw b777 evacuation

Except for the Commander and the senior cabin crewmember…all of the other occupants evacuated via the operational escape slides in approximately 6 minutes and 40 seconds.

a6emw b777 evacuation timeline

This is considerably beyond the 90 second certification target.

Twenty-one passengers, one flight crewmember, and six cabin crewmembers sustained minor injuries. Four cabin crewmembers sustained serious injuries.

a6emw b777 fire vehicle postioning

Approximately 9 minutes and 40 seconds after the Aircraft came to rest, the center wing tank exploded…

a6emw b777 explosion

…which caused a large section of the right wing upper skin [below] to be liberated.

a6emw b777 wing panel debris

As the panel fell to the ground, it struck and fatally injured a firefighter.

a6emw b777 dubai accident sequence 2

 

The Aircraft was eventually destroyed due to the subsequent fire.

AAIS Findings

These included:

  • The post-Accident examination reports did not find any evidence of any Aircraft component or system malfunctions.
  • The Aircraft was equipped with a long landing alerting system that annunciated a ‘long landing’ alert at a distance of 1,280 m beyond the runway 12L threshold, some 92 m further along the runway than the programed alert distance.
  • A number of essential information [sic] was not communicated to [the]flight crew. These included missed approaches, the reported windshear on short final by [earlier] flight IAW123, the continued gusting and windshear conditions, and the wind shift at runway 12L threshold from headwind to tailwind starting…
  • The takeoff/go-around (TO/GA) switches were most likely serviceable when the Commander pushed the switch…
  • Not all information related to the TO/GA switches inhibit logic was available either in the FCOM or in the FCTM. No reference was contained in these manuals as to why the A/T mode will not change when the TO/GA switches become inhibited.
  • The flight crew were not made aware that the TO/GA switches become inhibited when the aircraft is below 2 ft radio altitude for a period of time greater than three seconds.
  • The TO/GA switches are [also] designed to become inhibited after touchdown when the aircraft radio altitude is less than 2 ft radio altitude, the weight-on-wheels (WOW) is valid and either the left or right gear WOW indicates that the aircraft is in ‘ground’ mode.
  • The TO/GA switches are designed to be enabled when the aircraft radio altitude is more than 2 ft.
  • With the thrust levers at the idle thrust position and the aircraft above 2 ft radio altitude with the flaps out of the ‘up’ position, when the TO/GA switch is pushed for a go-around, the A/T will automatically advance both thrust levers to the TO/GA position and TO/GA thrust will be attained in approximately eight seconds.
  • Without the use of the A/T, and provided the manual advancement of the thrust levers from the idle thrust position to the TO/GA thrust position takes two seconds, from an engine thrust setting of idle to TO/GA will take approximately six seconds.
  • The Operator’s OM-A policy required the use of the A/T for engine thrust management for all phases of flight. This policy did not consider pilot actions that would be necessary during a go-around initiated while the A/T was armed and active and the TO/GA switches were inhibited.
  • The Operator’s normal go-around training did not contain information with regards to the time it would take for the engines to achieve TO/GA thrust either by manual advancement of the thrust levers or by use of the A/T after the TO/GA switch is pushed.
  • With the A/T armed and active, after touchdown or when the TO/GA switches are inhibited, the only means of increasing engine thrust for a go-around is manual advancement of the thrust levers. This will cause the A/T to disconnect and an AUTOTHROTTLE DISC message will appear on the engine information and crew alerting system (EICAS).
  • The B777 crew alerting system was not designed to give a configuration warning for a go-around with the engine thrust levers not advancing towards the TO/GA thrust position.
  • The B777 provides an alert to the flight crew and a EICAS amber caution message AIRSPEED LOW when the airspeed has decreased 30% into the lower amber band. …this message occurred when the Aircraft speed was 128 kt indicated airspeed (IAS).
  • The predictive windshear system is inhibited from giving windshear warning/alerts below 50 ft radio altitude.
  • The enhanced ground proximity warning system (EGPWS) is inhibited from providing immediate windshear warnings/alerts below 10 ft radio altitude.
  • The EGPWS manufacturer document Product Specification ̶ Mode 7 ̶ Windshear Alerting was capable of providing a windshear caution alert for aircraft performance increasing due to increasing headwind (or decreasing tailwind) and severe updrafts. However, this feature was not available to the flight crew because it was not enabled on the Aircraft.
  • Approximately 60 minutes prior to landing, the Commander and the Copilot completed a briefing for the approach to runways 30L and 12L, which included a windshear escape maneuver brief.
  • An approach speed of 152 kt (VREF +5) was selected for a normal landing configuration, with a flaps 30 setting.
  • In the eight minutes prior to the attempted landing…two aircraft performed go-arounds from beyond the runway threshold and two aircraft landed uneventful.
  • As the Aircraft descended through 930 ft radio altitude, the autopilot was disengaged and the approach continued with the A/T engaged.
  • The Aircraft passed over the threshold at approximately 54 ft radio altitude and airspeed 159 kt.
  • The Commander started to flare the Aircraft at approximately 40 ft radio altitude, approximately 100 m beyond the threshold. The FCTM recommends initiation of the flare when the main gear is approximately 20 to 30 ft above the runway surface.
  • At 25 ft radio altitude the engines started to spool down towards idle and the A/T mode changed to ‘IDLE’. The airspeed started to decrease and reached 153 kt at 10 ft radio altitude.
  • Prior to activation of the inhibit logics [sic], neither the Aircraft weather radar predictive windshear warning system nor the EGPWS immediate windshear warning system provided any windshear warning and/or alerts as the wind conditions that existed did not meet the windshear alerting design criteria.
  • …the wind conditions that existed up to 10 ft radio altitude did not have a decreasing and/or increasing performance effect on the Aircraft.
  • Passing 7 ft radio altitude, the Aircraft floated over the runway and at 2 ft radio altitude, the IAS reached 165 kt. There was a 12 kt airspeed increase in approximately four seconds, during which time the descent rate decreased.
  • The flight crew did not notice the increase in airspeed as they were both focused outside the Aircraft.
  • Even though the Commander was not aware of the increasing airspeed, he had responded to the increasing performance and in an attempt to land, three times made small pitch attitude corrections to lower the nose of the Aircraft.
  • Ten seconds after initiation of the flare at approximately 1,090 m beyond the touchdown zone and at an airspeed of 161 kt IAS, the TO/GA switches became inhibited, in accordance with TO/GA switch design logic, when the right main landing gear contacted the runway causing the gear to ‘untilt’.
  • The Commander, who was the pilot flying decided to fly a go-around, as he was unable to land the Aircraft within the runway touchdown zone.
  • The go-around decision was based on the perception that the Aircraft would not land due to thermals and not due to a windshear encounter. For this reason, the Commander elected to fly a normal go-around and not the windshear escape maneuver.
  • When the Commander initiated the go-around, his perception was that the Aircraft was still airborne and had not touched down. The left TO/GA switch was pushed approximately 2.5 seconds after the Aircraft had touched down.
  • The flight crew did not observe that the speedbrake lever had partially deployed twice during the six seconds the Aircraft main landing gear had cycled between ‘tilt’ and ‘untilt’.
  • During the attempted go-around, the Commander said that he became focused on the go-around maneuver and described his state as “tunnel visioned”.
  • The Commander had stated that his right hand remained on the thrust levers during the attempted go-around. After pushing the left TO/GA switch, the Commander did not recognise that there was no tactile feedback of thrust lever movement.
  • The flight crew did not observe that the FMA modes did not change and that the flight director was not giving pitch guidance. They were not aware that the A/T mode had remained at ‘IDLE’.
  • Contrary to the FCOM ̶ Go-around and Missed Approach Procedure, after ‘flaps 20’, the Commander and the Copilot omitted the steps of engine thrust verification and continued to action the procedure from the ‘positive climb’ item.
  • …the timing between the Copilot’s confirmation of ‘Flaps 20’ and the Commander’s call for ‘gear up’ was 2.5 seconds.
  • No action was taken to increase engine thrust because both flight crewmembers were unaware that the engine thrust was not increasing automatically after the TO/GA switch had been pushed and neither flight crewmember checked the EPR indicators.
  • The flight crew did not observe that the airspeed was decreasing as the Aircraft climbed.
  • Four seconds after the Aircraft became airborne passing 58 ft radio altitude, ATC communicated with the flight crew just after the Commander called ‘gear up’.
  • The Copilot responded to the ATC communication after selecting the landing gear to ‘up’. The Copilot did not check that the flight director was ‘on’ after selecting the landing gear lever to ‘up’ as required by the FCOM ̶Missed Approach and Go-Around Procedure.
  • The Aircraft reached 85 ft radio altitude and then started to sink back onto the runway.
  • As the Aircraft sank, at approximately 67 ft radio altitude, three seconds before impact, the Aircraft loss of airspeed was perceived by the Commander as a windshear effect, which prompted him to call “Windshear TOGA”.
  • The Commander pushed the TO/GA switch and manually advanced both thrust levers fully forward, as per the Operator’s windshear escape maneuver procedure. Only at this time did the Commander realize that the engines were not producing sufficient thrust.
  • The Aircraft impacted the runway 18 seconds after the go around command and with the landing gear transitioning to the up position.

Emirates’ policy, in line with Boeing’s recommendations, is for pilots to use autothrottle for all phases of flight including normal go-around.   Of note is that the crew did not perceive that the main landing gear had contacted (changing AT mode) and their minimal training and experience in flying go-arounds in that specific circumstance meant they did not recognise that the thrust remained at idle.  The investigators note the airline training programme was based on Boeing’s FAA approved training scheme which “did not include” the inhibition logic.   The inhibit logic characteristics for the go-around switches were therefore “not clearly demonstrated” to pilots.

Emirates has modified its training since the accident to reinforce training for go-around after touchdown and include information on the inhibit logic.  They have also been liaised with Boeing to develop “engineered defences” to alert the crew when a go-around switch is pushed during an inhibited phase.

After impact:

  • The Commander initiated the evacuation approximately one minute after the Aircraft came to rest. Part of this time was used to locate the evacuation checklist amongst the items that had been scattered around the cockpit during the impact.
  • For most of the evacuation, only one exit was usable in the forward cabin, while two exits were usable in the aft cabin. Five slides were affected by wind and these exits were permanently or temporarily blocked.
  • The cabin crew were not trained in evacuation situations where the escape slides are affected by wind.
  • The cabin crew managed the passenger evacuation to the highest professional standard, in line with their training.
  • During the evacuation, the prevailing wind speed and angle were within the TSO certification conformity testing criteria.
  • Due to the Aircraft coming to rest on its lower fuselage, the escape slides deployed at an angle of approximately 14 degrees. As per design, the escape slide deployed slope angle range is between 27 to 35 degrees, with the landing gear extended.
  • The R3 door escape ramp did not deploy automatically because the pressure cylinder was damaged due to the impact.
  • The protective breathing equipment (PBE) units were certified in accordance with two TSOs issued by the FAA. Some PBE units could not be used because the stowage containers or plastic pouches were difficult to open.
  • The response time of the first responding fire vehicles was within the regulatory requirements, however, the first two responding major foam vehicles (MFV) were positioned behind the trailing edge of the right wing and obstructed the escape paths of the evacuating passengers.
  • The fire commander did not correctly establish incident sectors and did not cover the area that extended from the right wing leading edge to the Aircraft nose. His view of the Accident site was limited because he positioned his vehicle inappropriately.
  • No dynamic risk assessment was conducted and sideline firefighters were moving very close to fuel tanks where there was a potential explosion hazard. Crew managers did not communicate details of the firefighting actions to the fire commander.
  • The ARFFS training system could not detect the lack of knowledge, understanding, and experience in aircraft incident command and firefighting tactics. Exercises were limited to simple fire scenarios and no appropriate simulated techniques were developed to challenge the fire commanders, sector commanders, crew managers, and firefighters to assess fire dynamics and develop appropriate tactics.

The investigators also comment that:

…based on heightened industry concerns about loss of control during high energy go-arounds, as documented by the Flight Safety Foundation and the United Kingdom Civil Aviation Authority (UK CAA), the Operator’s Group Safety Department conducted a safety review of FDM recorded go-arounds. The review revealed occasional instances of noncompliance with standard operating procedures, which included landing gear retraction prior to flap selection, and occasional instances of altitude deviations when go-arounds were flown without having the missed approach altitude pre-set, which led to the aircraft exceeding the intended altitude. The safety review results were presented and discussed by the Training Review Committee in January 2014. Following this, all engines operating go-arounds for various reasons and from various altitudes were introduced into several flight crew-training modules. Related flight crew information regarding mishandled go-arounds was also published in the Operator’s flight safety publication in May 2014.

The Investigation believes that predictions of a multi-layered failure of the safety net are a challenge for a safety management system. However, some factors and recommendations pertinent to the…Accident were present within the industry but were not analyzed in context with thrust verification due to the absence of a reference event. It is therefore believed that the key to a proactive SMS is a coordinated and structured data sharing initiative within the industry, spearheaded by the aircraft manufacturers. This Accident could potentially lead to a set of identified precursors being shared within the industry, to be adopted and monitored by individual airlines’ FDM programs.

Causes

(a) During the attempted go-around, except for the last three seconds prior to impact, both engine thrust levers, and therefore engine thrust, remained at idle. Consequently, the Aircraft’s energy state was insufficient to sustain flight.

(b) The flight crew did not effectively scan and monitor the primary flight instrumentation parameters during the landing and the attempted go-around.

(c) The flight crew were unaware that the autothrottle (A/T) had not responded to move the engine thrust levers to the TO/GA position after the Commander pushed the TO/GA switch at the initiation of the FCOM ̶ Go-around and Missed Approach Procedure.

(d) The flight crew did not take corrective action to increase engine thrust because they omitted the engine thrust verification steps of the FCOM ̶ Go-around and Missed Approach Procedure.

Contributing Factors

(a) The flight crew were unable to land the Aircraft within the touchdown zone during the attempted tailwind landing because of an early flare initiation, and increased airspeed due to a shift in wind direction, which took place approximately 650 m beyond the runway threshold.

(b) When the Commander decided to fly a go-around, his perception was that the Aircraft was still airborne. In pushing the TO/GA switch, he expected that the autothrottle (A/T) would respond and automatically manage the engine thrust during the go-around.

(c) Based on the flight crew’s inaccurate situation awareness of the Aircraft state, and situational stress related to the increased workload involved in flying the go-around maneuver, they were unaware that the Aircraft’s main gear had touched down which caused the TO/GA switches to become inhibited. Additionally, the flight crew were unaware that the A/T mode had remained at ‘IDLE’ after the TO/GA switch was pushed.

(d) The flight crew reliance on automation and lack of training in flying go-arounds from close to the runway surface and with the TO/GA switches inhibited, significantly affected the flight crew performance in a critical flight situation which was different to that experienced by them during their simulated training flights.

(e) The flight crew did not monitor the flight mode annunciations (FMA) changes after the TO/GA switch was pushed because: 1. According to the Operator’s procedure, as per FCOM ̶Flight Mode Annunciations (FMA), FMA changes are not required to be announced for landing when the aircraft is below 200 ft; 2. Callouts of FMA changes were not included in the Operator’s FCOM ̶ Go-Around and Missed Approach Procedures. 3. Callouts of FMA changes were not included in the Operator’s FCTM Go-Around and Missed Approach training.

(f) The Operator’s OM-A policy required the use of the A/T for engine thrust management for all phases of flight. This policy did not consider pilot actions that would be necessary during a go-around initiated while the A/T was armed and active and the TO/GA switches were inhibited.

(g) The FCOM ̶ Go-Around and Missed Approach Procedure did not contain steps for verbal verification callouts of engine thrust state.

(h) The Aircraft systems, as designed, did not alert the flight crew that the TO/GA switches were inhibited at the time when the Commander pushed the TO/GA switch with the A/T armed and active.

(i) The Aircraft systems, as designed, did not alert the flight crew to the inconsistency between the Aircraft configuration and the thrust setting necessary to perform a successful go-around.

(j) Air traffic control did not pass essential information about windshear reported by a preceding landing flight crew and that two flights performed go-arounds after passing over the runway threshold. The flight crew decision-making process, during the approach and landing, was deprived of this critical information.

(k) The modification of the go-around procedure by air traffic control four seconds after the Aircraft became airborne coincided with the landing gear selection to the ‘up’ position. This added to the flight crew workload as they attentively listened and the Copilot responded to the air traffic control instruction which required a change of missed approach altitude from 3,000 ft to 4,000 ft to be set. The flight crews’ concentration on their primary task of flying the Aircraft and monitoring was momentarily affected as both the FMA verification and the flight director status were missed.

Safety Recommendations

Forty recommendations are made in the final report.  They include one that FAA, with Boeing, studies to enhancing the 777 autothrottle system and go-around inhibit logic and another that flight crew manuals should have the significance of the inhibit logic “appropriately” highlighted.

Afternote

On release of the report, Adel Al Redha, Emirates’ CEO, said:

In addition to actions identified in the Final Report, Emirates has also proactively taken the appropriate steps to further enhance our operating procedures based on our own internal investigation, as well as on a thorough review of the Preliminary Report and Interim Report. These actions were taken in conjunction with our regulator, the UAE GCAA. It is a positive validation of our robust internal process that the majority of our own findings and recommendations are included in the final report.  …we are committed to the continuous review and improvement of our operations.

Note: All graphics are from the AAIS report.

Other Safety Resources

See EASA Safety Information Bulletin SIB 2014-09 : Aeroplane Go-Around Training and our articles:

Aerossurance has extensive air safety, operations, airworthiness, human factors, aviation regulation and safety analysis experience.  For practical aviation advice you can trust, contact us at: enquiries@aerossurance.com