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Emirates EK521

Accident Case Study

 


 

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Photo: Emirates EK521 wreckage, from Reuters.

Accident Report

  • Date: 3 August 2016
  • Time: 08:37 UTC
  • Type: Boeing 777-31H
  • Operator: Emirates
  • Registration: A6-EMW
  • Fatalities: 0 of 18 crew, 0 of 282 passenger, 1 ground casualty
  • Aircraft Fate: Destroyed
  • Phase: Landing Go-Around
  • Airport: Dubai International Airport (OMDB), the United Arab Emirates

Narrative

[AAIS, ¶1.1]

  • On 3 August 2016, an Emirates Boeing 777-300 Aircraft, registration A6-EMW, operating a scheduled passenger flight EK521, departed Trivandrum International Airport (VOTV), India at 0506 for Dubai International Airport (OMDB), the United Arab Emirates. At approximately 0837, the aircraft impacted the runway during an attempted go-around at Dubai.
  • There were a total of 300 people onboard the aircraft, comprising 282 passengers, two flight crewmembers, and 16 cabin crewmembers.
  • The commander, seated in the left hand (LH) seat, 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 0836:00, 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 0836:22, and at 154 knots IAS, it was subjected to a tailwind component which gradually increased to a maximum of 16 knots.
  • At 0837:07, 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 0837:12, 160 knots IAS, and 5 feet RA, five seconds before touchdown, the wind direction again started to change to a headwind.
  • As recorded by the Aircraft flight data recorder, the weight-on-wheels sensors indicated that the right main landing gear touched down at 0837:17, 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 0837:19, the aircraft runway awareness advisory system (RAAS) aural message “LONG LANDING, LONG LANDING” was annunciated.
  • At 0837:23, the aircraft became airborne in an attempt to go-around and was subjected to a headwind component until impact. At 0837:27, 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 0837:28, 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 0837:35, 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 0837:38, 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 commander transmitted a “MAYDAY” call and informed air traffic control that the aircraft was being evacuated.
  • Together with the fire commander, 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 commander 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.
  • 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.
  • The point of impact of the aircraft with the runway was approimately 2,530 meters [8,300 feet] from runway 12L threshold, adjacent to the November 7 taxiway. Marks on the runway indicated that the aircraft slid for approximately 800 meters [2,625 feet] along the runway with the three landing gears not fully up. The aircraft came to rest adjacent to the Mike 13 taxiway, having turned to the right onto a heading of approximately 240 degrees.

[AAIS, ¶1.17.2]

  • The current flight crew operating manual (FCOM) and the flight crew training manual (FCTM) used by the operator contained go-around procedures and the applicable training guidance.
  • The FCOM systems description under the heading Automatic Flight – Go-Around, chapter 4.20.17, states that “Pushing either TO/GA switch activates a go-around. The mode remains active even if the airplane touches down while executing the go–around.” In addition, the FCOM states that “The TO/GA switches are inhibited when on the ground and enabled again when in the air for a go–around or touch and go.”
  • The FCOM normal Go-Around and Missed Approach procedure, chapter NP.21.56, describes the actions and call-outs required by the PF and the PM.
  • In the FCTM under the heading Rejected Landing, chapter 6.28, it is stated that the FCOM/QRH does not contain a procedure or maneuver titled ‘rejected landing’ and the requirements for maneuver can be accomplished by doing a go-around procedure if it is initiated before touchdown. The following is stated in the FCTM:
  • “Rejected Landing

    A rejected landing maneuver is trained and evaluated by some operators and regulatory agencies. Although the FCOM/QRH does not contain a procedure or maneuver titled Rejected Landing, the requirements of this maneuver can be accomplished by doing the Go-Around Procedure if it is initiated before touchdown. Refer to Chapter 5, Go-Around after Touchdown, for more information on this subject.”

  • The FCTM under the heading Go-Around and Missed Approach – All Engines Operating, chapter 5.67, states that the go-around and missed approach shall be performed according to the Go-Around and Missed Approach procedure described in the FCOM. The FCTM also states that “During an automatic go-around initiated at 50 feet, approximately 30 feet of altitude is lost. If touchdown occurs after a go-around is initiated, the go-around continues. Observe that the autothrottle apply go-around thrust or manually apply go-around thrust as the airplane rotates to the go-around attitude.” Below this statement, there is a note which states that “An automatic go-around cannot be initiated after touchdown.”
  • The FCTM Go-Around after Touchdown, chapter 5.69, states that:
  • “If a go-around is initiated before touchdown and touchdown occurs, continue with normal go-around procedures. The F/D [flight director] go-around mode will continue to provide go-around guidance commands throughout the maneuver.

    If a go-around is initiated after touchdown but before thrust reverser selection, continue with normal go-around procedures. As thrust levers are advanced auto speedbrakes retract and autobrakes disarm. The F/D go-around mode will not be available until go- around is selected after becoming airborne.”

Analysis

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Drawing: Emirates EK521 final flightpath, from AAIS, Appendix A.

[AAIS, ¶1.6.2]

  • During the landing and attempted go-around, the aircraft was in a rapidly changing and dynamic flight environment. The initial touchdown and transition of the aircraft from air to ground mode, followed by the lift-off and the changes in the aircraft configuration in the attempted go-around, involved operational modes, logics and inhibits of a number of systems, including the autothrottle, the air/ground system, the weather radar, and the GPWS.
  • The characteristics of these systems, and others, will be examined during the course of the Investigation.
  • The only explanation I can come up with what follows does not seem possible, so I must wait until the final report to speculate.

[AAIS, Appendix A.] The flare was initiated as the aircraft crossed the threshold.

[AAIS, ¶1.1] The autothrottle mode transitioned to IDLE and both thrust levers were moving towards the idle position. At . . . 5 feet RA, five seconds before touchdown, the wind direction again started to change to a headwind.

This kind of windshear should not be a factor at this altitude; the pilot's eyes should be on the far end of the runway and maintaining a downward sink rate, not trying to finesse the landing to zero VVI. Looking for that kind of "greaser" can turn into an excessive float, which appears to be what happened.

It appears the pilot then attempted a go around by simply pitching up, reducing the flaps to a go around setting, and retracting the landing gear.

[AAIS, Appendix A.] The right main landing gear made contact 3,600' from the threshold and the left main landing gear at 4,500' from the threshold.

It was indeed a long landing and the decision to reject the landing was valid, though it was made a bit late.

[AAIS, ¶1.1] 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 0837:35, 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.

It appears the throttles did not advance in response to a TO/GA actuation because they were at idle until this point.

[AAIS, Appendix B.] Emirates Boeing 777 Flight Crew Operations Manual, Automatic Flight - System Description

  • With the first push of either TO/GA switch:
    • roll and pitch activate in TO/GA
    • autothrottle activates in thrust (THR) to establish a minimum climb rate of 2,000 fpm
    • the AFDS increases pitch to hold the selected speed as thrust increases
    • if current airspeed remians agvoe the target speed for 5 seconds, the target speed is reset to current airspeeed (to a minimum of the IAS/MACH window speed plus 25 knots).

Probable Cause

To be determined.

See Also

Landing

Windshear

References

Air Accident Investigation Sector (AAIS) Accident Preliminary Report, Case No: AIFN/0008/2016, Runway Impact During Attempted Go-Around, Emirates, Boeing 777-31H, A6-EMW, Dubai International Airport, The United Airab Emirates, 3 August 2016

Revision: 20160816
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