Description

On 27 July 2010, a Boeing MD11F being operated by Lufthansa Cargo on a scheduled flight from Frankfurt to Riyadh bounced twice prior to a third hard touchdown whilst attempting to land on 4205 metre-long Runway 33L at destination in normal day visibility. The fuselage was ruptured and, as the aircraft left the side of the runway, the nose landing gear collapsed and a fire began to take hold. A ‘MAYDAY’ call was made as the aircraft slid following the final touchdown. Once the aircraft had come to a stop, the two pilots evacuated before it was largely destroyed by fire. One pilot received minor injuries, the other injuries described as major.

Investigation

An Investigation was carried out by the Air Safety Division of the Saudi Arabian General Authority of Civil Aviation (GACA). The DFDR and 30 minute Cockpit Voice Recorder (CVR) were retrieved from the wreckage and although both units were fire damaged, successful replay was achieved. It was noted that whilst the aircraft commander, who had been acting PM, was experienced on the MD11, the First Officer acting as PF had only recently completed initial line training and on type after previous experience only as an Airbus A319 First Officer.

It was found that the manual approach with autothrottle (A/T) off had been normal until shortly before touchdown when the sink rate and speed increased and the flare was not begun until about 20 feet agl, later than appropriate for the prevailing aircraft weight. The Initial touchdown at V_ref +18 was hard at 780 fpm / 2 g and after a further bounce from main and nose gear, a final touchdown occurred 945 metres from the runway threshold at 1020 fpm / 4.49 g, the aft fuselage ruptured and a fuel-fed fire began in the left hand wheel well. The aircraft continued to decelerate and departed the left side of the runway at 2255 metres from the threshold before coming to a stop some 90 metres off it (see the picture below) where the fire took hold and much of the aircraft and its cargo were destroyed. The two pilots successfully evacuated the aircraft; one had received major spinal injuries during the hard runway contacts and the other had only minor cuts to the head.

Although an ignition source for the post crash fire could not be determined, available evidence suggested that it had been fed by fuel sprayed from a break in the pressurised 5cm diameter no. 2 engine/APU fuel line and the unpressurised tail tank fuel transfer line. It was noted that the Halon 1301 fire suppression systems fitted to both the main deck and the belly holds had not been activated

In respect of the fuselage fracture, it was found that Centre of Gravity limit load factor for the aircraft type is 2.3 g, which leads to an ultimate (vertical) factor based on 14 CFR 25.3030 requirements of 3.5 g, a figure exceeded by a significant margin at the final touchdown.

It was noted that the Operations Manual included the following in respect of sink rate at touchdown:

“Normal sink rate at touchdown averages to 120 ft/min. An aeroplane is certified with a sink rate of 360 ft/min at the structural(ly) limited TOW and with 600 ft/min at the maximum landing weight. Structural problems will not arise if sink rates at touchdown do not exceed 360 ft/min.”

Other guidance material issued to MD11 pilots by the Operator stated that:

“flare height: depends on weight because of the mass inertia. At high weights (>200 tonnes) the flare has to be initiated in the vicinity of 40 feet (agl). At light weights (around 130 tonnes) a flare just prior 20 feet (agl) is sufficient. Furthermore, pressure altitude influences the flare height - due to the higher True Airspeed and the corresponding(ly) higher vertical speed, the flare has to be initiated a bit earlier than usual”

The ELW of the accident aircraft was 207 tonnes.

The Investigation noted that there had been a total of 29 MD11 bounced landings which had resulted in ‘substantial aircraft damage’ during the period 2 August 1992 to 27 July 2010. Many of these, like the investigated event, began with a first touchdown which resulted in a bounce but one from which recovery to a subsequently safe landing was possible. The Investigation noted that in the specific case of the investigated event, “the severity of the subsequent touchdowns was not a consequence of the first touchdown, but primarily a result of the pitch angle during the bounces, which resulted from the actions of both flight crews on the control column”.

In respect of pilot training for bounced landing recovery, the Investigation concluded that “The MD-11 simulator did not provide a true and accurate simulation of the bounce conditions found with the aircraft. The artificial actions to initiate a bounce in the simulator reduced the value of the training.”

The Investigation identified the following sequence of “Cause Related Findings”:

• The flight crew did not recognise the increasing sink rate on short final.
• The First officer delayed the flare prior to the initial touchdown, thus resulting in a bounce.
• The flight crew did not recognise the bounce.
• The Captain attempted to take control of the aircraft without alerting the First Officer resulting in both flight crews acting simultaneously on the control column.
• During the first bounce, the Captain made an inappropriate, large nose-down column input that resulted in the second bounce and a hard landing in a flat pitch attitude.
• The flight crew responded to the bounces by using exaggerated control inputs.
• The company bounced-landing procedure was not applied by the flight crew.

A number of secondary aspects of the response to the accident, both some directly relevant to accident scenarios and others merely highlighted by the response were also reviewed.

A total of 9 Safety Recommendations were made as a result of the Investigation, the first two being “Stand Alone Recommendations” issued by the United States NTSB on 12 July 2011 after prior agreement with the Saudi Arabian GACA. The first of these was noted to have been promptly actioned by Boeing as recommended.

• The FAA should require Boeing to revise its MD-11 Flight Crew Operating Manual to reemphasize high sink rate awareness during landing, the importance of momentarily maintaining landing pitch attitude after touchdown and using proper pitch attitude and power to cushion excess sink rate in the flare, and to go around in the event of a bounced landing [NTSB A-11-68]
• Once Boeing has completed the revision of its MD-11 Flight Crew Operating Manual as recommended in (NTSB) Safety Recommendation A-11-68, the FAA should require all MD-11operators to incorporate the Boeing-recommended bounce recognition and recovery procedure in their operating manuals and in recurrent simulator training. [NTSB A-11-69]
• The Operator should consider installing Head-Up Displays (HUDs) on its MD-11F aircraft.
• The GACA shall ensure that all Departments using recording devices at both International and Domestic airports throughout the KSA synchronize the time of the recording devices with the ATC time.
• The GACA shall ensure that Airport Security Services properly cordon-off accident sites to avoid the possibility of serious/fatal injuries to bystanders and, allow only the authorized personnel and equipment to enter the cordoned-off area, as per the Airport Emergency Plan.
• The GACA shall ensure that all personnel involved in fire fighting operations wear the appropriate Personal Protection Equipment (PPE) when required.
• The GACA should consider installing cameras with recording capability at all its airports within the KSA to cover all movement areas for security purposes and to supplement information available for investigation of aviation occurrences.
• The GACA shall ensure that the KKIA Airport Operations Department have a functioning recording device for all its communications.
• The GACA shall ensure that all vehicles operating within the KKIA airport boundaries are equipped with rotating beacons.

The Final Report of the Investigation was approved by the Board of the GACA on 21 January 2012.

Further Reading

• Runway Excursion
• Stabilised Approach
• Landing Flare
• Runway Overrun On Landing (OGHFA SE)
• Adherence to SOPs (OGHFA BN)
• Emergency Evacuation on Land
• Engine Fire Protection