Air investigation: TO/GA confusion factor in Emirates Boeing 777 accident in Dubai in 2016
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Topics: AIR INVESTIGATION EMIRATES BOEING DUBAI
All 300 on board survived the accident. One fire fighter was killed during the ARFF operations.
The aircraft departed Thiruvananthapuram, India at 05:06 hours UTC. The captain was the pilot flying (PF), and the copilot was the pilot monitoring (PM). As the flight neared Dubai, the crew received the automatic terminal information service (ATIS) Information Zulu, which included a windshear warning for all runways.
The aircraft was configured for landing with the flaps set to 30, and approach speed selected of 152 knots (VREF + 5) indicated airspeed (IAS) The aircraft was vectored for an area navigation (RNAV/GNSS) approach to runway 12L.
Air traffic control cleared the flight to land, with the wind reported to be from 340 degrees at 11 knots, and to vacate the runway via taxiway Mike 9.
During the approach, at 08:36:00 UTC (12:36 local time), with the autothrottle system in SPEED mode, as the aircraft descended through a radio altitude (RA) of 1,100 feet, at 152 knots IAS, the wind direction started to change from a headwind component of 8 knots to a tailwind component.
The autopilot was disengaged at approximately 920 feet RA and the approach continued with the autothrottle connected.
As the aircraft descended through 700 feet RA at 08:36:22, and at 154 knots IAS, it was subjected to a tailwind component which gradually increased to a maximum of 16 knots.
At 08:37:07, 159 knots IAS, 35 feet RA, the PF started to flare the aircraft.
The autothrottle mode transitioned to IDLE and both thrust levers were moving towards the idle position.
At 08:37:12, 160 knots IAS, and 5 feet RA, five seconds before touchdown, the wind direction again started to change to a headwind.
The right main landing gear touched down at 08:37:17, approximately 1,100 meters from the runway 12L threshold at 162 knots IAS, followed three seconds later by the left main landing gear. The nose landing gear remained in the air.
At 08:37:19, the aircraft runway awareness advisory system (RAAS) aural message "LONG LANDING, LONG LANDING" was annunciated.
At 08:37:23, the aircraft became airborne in an attempt to go-around and was subjected to a headwind component until impact.
At 08:37:27, the flap lever was moved to the 20 position.
Two seconds later the landing gear lever was selected to the UP position.
Subsequently, the landing gear unlocked and began to retract.
At 08:37:28, the air traffic control tower issued a clearance to continue straight ahead and climb to 4,000 feet. The clearance was read back correctly.
The aircraft reached a maximum height of approximately 85 feet RA at 134 knots IAS, with the landing gear in transit to the retracted position. The aircraft then began to sink back onto the runway.
Both crewmembers recalled seeing the IAS decreasing and the copilot called out "Check speed."
At 08:37:35, three seconds before impact with the runway, both thrust levers were moved from the idle position to full forward. The autothrottle transitioned from IDLE to THRUST mode.
Approximately one second later, a ground proximity warning system (GPWS) aural warning of "DON’T SINK, DON’T SINK" was annunciated.
One second before impact, both engines started to respond to the thrust lever movement showing an increase in related parameters.
At 08:37:38, the aircraft aft fuselage impacted the runway abeam the November 7 intersection at 125 knots, with a nose-up pitch angle of 9.5 degrees, and at a rate of descent of 900 feet per minute.
This was followed by the impact of the engines on the runway. The three landing gears were still in transit to the retracted position. As the aircraft slid along the runway, the No.2 engine-pylon assembly separated from the right hand (RH) wing.
From a runway camera recording, an intense fuel fed fire was observed to start in the area of the damaged No.2 engine-pylon wing attachment area. The aircraft continued to slide along the runway on the lower fuselage, the outboard RH wing, and the No.1 engine.
An incipient fire started on the underside of the No.1 engine. The aircraft came to rest adjacent to the Mike 13 taxiway at a magnetic heading of approximately 240 degrees. After the aircraft came to rest, fire was emanating from the No.
2 engine, the damaged RH engine-pylon wing attachment area and from under the aircraft fuselage.
Approximately one minute after, the captain transmitted a "MAYDAY" call and informed air traffic control that the aircraft was being evacuated.
Together with the fire captain, the first vehicle of the airport rescue and firefighting service (ARFFS) arrived at the Accident site within one minute of the aircraft coming to rest and immediately started to apply foam.
Additional firefighting vehicles arrived shortly after.
Apart from the captain and the senior cabin crewmember, who both jumped from the L1 door onto the detached slide, crewmembers and passengers evacuated the aircraft using the escape slides, though not all exits could be used as some slides were blown up against the aircraft.
The slide at the L1 door deflated after several passengers had evacuated.
Twenty-one passengers, one flight crewmember, and one cabin crewmember sustained minor injuries, and a second cabin crewmember sustained a serious injury.
Approximately nine minutes after the aircraft came to rest, a firefighter was fatally injured as a result of the explosion of the center fuel tank.
Probable Cause:
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 thrustduring 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 thego-around maneuver, they were unaware that the Aircraft’s main gear hadtouched 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. ■