Emirates A6-EWC

Departure from Dubai

Emirates flight EK211 was preparing to depart Dubai International Airport for Houston on 8 August 2010. The Boeing 777-200LR, registered A6-EWC, carried 269 passengers, four flight crewmembers and fourteen cabin crewmembers. The commander was the pilot flying. The aircraft used the full length of runway 12R, and its takeoff mass was 5,767 kilograms below the maximum certified takeoff mass. The crew had correctly calculated a V1 decision speed of 178 knots.

The aircraft had been manufactured in November 2007 and had undergone its latest A maintenance check on 16 July 2010. Investigators found that it was airworthy when dispatched. They also found the flight crewmembers licensed, medically fit, qualified and adequately rested. Weather and navigation aids were excluded as factors. Communications between the aircraft and Dubai air traffic control were good, as were communications between the flight deck and cabin.

The recorder timeline placed the aircraft on the runway at 05:55:18 UTC. The thrust levers were advanced at 05:55:34, engine thrust stabilised at 55% N1, and takeoff thrust reached 100% N1 at 05:55:43. Computed airspeed reached 80 knots at 05:56:00 and 100 knots five seconds later. The flight history described the occurrence time as approximately 05:57.

Tread debris and the decision to stop

At approximately 170 knots, the crew heard a loud bang. Tyre debris flew up in front of the aircraft and significant vibration came from the nose gear. The right nose wheel tyre had shed its tread, and pieces struck the underside of the forward fuselage. The impacts produced loud bangs in the cockpit. The commander judged that the aircraft was unsafe or unable to fly and rejected the takeoff before V1.

The recorders captured a vertical acceleration spike of 1.539G at 05:56:24. Two seconds later the forward thrust levers began moving from takeoff thrust to the closed position, a movement completed within one second. The speedbrake lever moved up at 05:56:27. The aircraft continued accelerating briefly after the stopping actions began, reaching a maximum computed airspeed of 176 knots. Its recorded groundspeed at that point was 183 knots.

Maximum reverse thrust was selected at 05:56:30, when the ground spoilers also extended. Maximum reverse thrust was established four seconds later. At 05:56:41 computed airspeed had fallen to 60 knots and the reverse thrust levers moved towards reverse idle. The aircraft stopped on the runway centreline at 05:56:50, approximately 1,216 metres before the runway end. The report treated its calculated runway distances as approximate.

Brake heating and disembarkation

After stopping, the crew notified air traffic control and the airport fire service attended. The commander alerted the cabin crew. The high energy rejection heated the brakes and triggered a brake temperature warning on the engine indication and crew alerting system. The recorder timeline put the indication and the first main gear tyre deflation through a fuse plug at 06:00:39. The main gear tyres deflated following the stop.

The crew kept the aircraft stationary, started the auxiliary power unit and shut down the engines. Firefighters reported smoke from the main gear area and cooled the brakes with water. Investigators found no indication of fire. The commander told passengers over the public address system that a tyre failure had caused the takeoff rejection and that they would leave using steps. All passengers had disembarked within 25 minutes of the event.

All 287 occupants were uninjured. Damage included dents and impact marks on the lower fuselage behind the nose gear, rubber marks ahead of the nose gear bay and destruction of a nose gear landing light. All main gear axles required replacement because of the deceleration forces and heating of the brake assemblies during and after the stop. There was no damage to property or the environment.

Recorded evidence

A6-EWC carried a flight data recorder, cockpit voice recorder and quick access recorder. The quick access recorder served the operator's monitoring of flight data and aircraft systems, recording most flight data recorder parameters as well as additional parameters selected by the operator. The flight data recorder received parameters through the digital flight data acquisition function, which converted the incoming information into digital form before passing it to the recorder.

The cockpit voice recorder operated continuously while the aircraft electrical system was powered and its circuit breaker was closed. It recorded the most recent 120 minutes of cockpit audio and was deactivated after the incident. The AAIS downloaded both the flight data recorder and cockpit voice recorder at its laboratory in Abu Dhabi. Both contained usable data. Investigators used the onboard recordings to construct the timed sequence of thrust changes, speedbrake movement, speed, stopping and subsequent tyre deflation. The timeline listed an accelerate stop distance available of 4,570 metres for runway 12R.

What the tyre examination found

The failed right nose wheel tyre was a Bridgestone radial tyre manufactured in December 2007. It had received its first retread in January 2010 and had completed 54 landings at the time of the incident. The report recorded an inflation pressure of 229 psi and approximately 6.5 mm of remaining skid depth. Investigators sent the failed tyre for laboratory examination.

The outboard sidewall appeared normal. On the inboard side, examiners found seven large bulges around the upper sidewall and shoulder. Most of the tread crown had detached from the casing, while the outboard shoulder rib remained firmly attached. The separation ran along the upper surface of the first belt ply and the original rubber beneath the tread. The pattern of detachment indicated good adhesion.

Airport personnel recovered approximately half of the detached tread. A recovered section had a large notch, 46 mm long and 17 mm wide, in the centre rib. Directly beneath this notch, the rubber showed a smooth separated surface and blue discolouration. The laboratory attributed these features to heat generated by internal friction. It found no separation or structural anomaly within the casing plies and concluded that impact with a blunt foreign object had caused the tread separation.

Foreign object damage and its limits

The AAIS concluded that the tyre had probably rolled over an object without sharp edges or corners. The impact made a deep indentation and damaged the tyre, leading to the tread separation during takeoff. The foreign object was never recovered. Investigators could not determine where or when the contact occurred: possible locations included the taxi route and runway, and contact on an earlier occasion also remained possible.

The final findings identified tread separation of the right nose wheel tyre as the cause of the incident and foreign object damage as a contributing factor. The investigators examined the wider debris hazard through the UAE reporting database. They explained that mandatory reporting covered Category A debris likely to damage aircraft on runways or runway shoulders, while reports from other categories were optional. The database therefore mainly reflected mandatory reports.

Dubai already had a debris prevention programme when the incident occurred. The airport strengthened it afterwards, with training, inspections, maintenance and debris reduction measures. At national level, the UAE National Runway Safety Team was established in November 2012. Its safety plan for 2014 to 2016 included foreign object debris prevention among the areas selected for further work.

The crew response and safety recommendations

Emirates procedures gave the commander responsibility for deciding on and performing a rejected takeoff. Between 80 knots and V1, the listed reasons included an engine failure, fire or fire warning, predictive windshear warning, or an aircraft judged unsafe or unable to fly. The AAIS found that both pilots coordinated their actions and completed the rejection in accordance with the operator's procedures.

The investigation considered the risks of rejecting at high speed. The nose wheels provided no braking, the second nose tyre remained intact and the tyre that lost its tread stayed inflated. However, the detached tread striking the fuselage created the noises that led the commander to stop. The report also described how the high energy rejection generated temperatures capable of causing additional tyre failures.

The GCAA issued two recommendations. SR 39/2015 called for consideration of an enhanced UAE debris prevention programme. SR 40/2015 called for effective debris programmes at all UAE aerodromes. The final findings said the national prevention provision had been developed but was still awaiting full deployment and implementation.

The airport described a three tier inspection system, including inspections by senior management every six months and participation by its safety action group. Cleaning arrangements covered ground support equipment roads as well as runways, taxiways and aprons. A February 2015 update reported weekly runway cleaning and twice daily cleaning of taxiway crossings. Staff also cleaned critical areas manually, with cleaning personnel positioned in baggage handling areas and on aprons.

Training and campaigns involved airport stakeholders as well as airside controllers. Debris prevention formed part of annual development training and competency assessments. Stakeholders organised walks to collect debris and raise awareness, while runway debris was monitored as a key performance indicator at safety meetings. The airport also reported directions to construction contractors covering debris bins, sweepers and inspections.

Dubai Airports reported expanded inspections, cleaning of runways, taxiways and aprons, stakeholder debris walks and training. It also reported purchase and installation of the iFerret detection system, with operation expected in the first quarter of 2016. These actions and plans were recorded in the AAIS final report dated 23 July 2015.