Srilankan A332 at Colombo on Jul 8th 2024, temporary runway excursion on landing

Last Update: February 13, 2025 / 20:49:47 GMT/Zulu time

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Incident Facts

Date of incident
Jul 8, 2024

Classification
Incident

Airline
Srilankan Airlines

Flight number
UL-226

Departure
Dubai, United Arab Emirates

Destination
Colombo, Sri Lanka

Aircraft Registration
4R-ALS

Aircraft Type
Airbus A330-200

ICAO Type Designator
A332

A Srilankan Airbus A330-200, registration 4R-ALS performing flight UL-226 (dep Jul 7th) from Dubai (United Arab Emirates) to Colombo (Sri Lanka), landed on Colombo's runway 22 but veered left off the runway before returning onto the runway center line. The aircraft slowed without further incident and taxied to the apron.

On Jul 19th 2024 Sri Lanka's CAA reported the aircraft left the runway while landing and opened an investigation into the occurrence rated a serious incident.

On Feeb 13th 2025 Sri Lanka's CAA released their final report concluding the probable causes of the incident were:

The probable cause is the flight crew’s decision to land the aircraft without initiating a go-around by misjudging the magnitude of the left deviation from the runway centre line.

The contributing factors are;

a. Improper application of flight control inputs by PF and the reversing of crosswind component from left to right,
b. Lack of flight deck leadership of PIC and poor situational awareness and decision making by flight crew which was triggered by incorrect perception and cognitive biases.

The CAA analysed:

Handling of the aircraft

Initial stage of the final approach, the autopilot was engaged and was maintaining the aircraft on the extended runway centreline. At approximately 390ft RA, the flight crew voluntarily disengaged both APs via the sidestick instinctive pushbutton. Then final approach was manually handled by the First Officer (PF) with the A/THR active in SPEED mode.

After the autopilot was disengaged, when the aircraft was about 150ft RA, PF applied several left and right roll orders with a left roll tendency, leading the roll angle to increase up to a maximum of -3.5° (left roll): the roll angle was thus mainly a left roll in the last 10 seconds before touchdown. The left roll angle maintained for 10 seconds, associated with the crosswind reversion, initiated a localizer deviation to the left of the runway centreline.

Approximately 20ft RA, most probably to counter the left deviation, the flight crew applied a rightward pedal order up to half of full deflection (crab action). However, the rightward pedal inputs applied by PF was not sufficient to arrest the leftward drift of the aircraft. This rightward rudder pedal order (crab action), associated with the crosswind reversion, led the drift angle to increase (aircraft nose toward the right of the track) prior to touchdown.

As recommended in the Flight Crew Techniques Manual (FCTM), the rudder should be used during the flare to align the aircraft with the runway heading (decrab technique) and the roll control should be used, if needed, to maintain the aircraft on the runway centreline. According to the aircraft manufacturer’s operational and safety documentation, the right technique to correct minor lateral deviation during approach is to apply small amount of roll input. In this case, the flight crew should have applied more right roll input instead of right rudder input. Applying rudder input is not an appropriate method to correct lateral deviations.

As mentioned in Section 1.1, the PF had tried to land without success to prevent the aircraft from continuing to drift towards the left edge of the runway. The aircraft touched down at approximately 250m after the runway threshold with the left main landing gear on the runway shoulder (out of runway) and with the right main landing gear still on the runway. The runway was recovered (all main landing gears were on the runway) around 700m after threshold and the runway centreline was recovered around 900m after threshold.

Weather condition over the aerodrome

The aircraft was flying through light rain during the final approach. The PIC (PM) confirmed that according to the ATC information wind was calm, light rain was prevailing and runway condition was wet. According to the PF, due to light rain visibility was around 05-06 km and they requested to increase the intensity of runway lights on finals. Both PF and PM (PIC) explained that they understood wind was veering and during touchdown it was from the right.

According to ATC, they should inform pilots of the prevailing weather if it has changed significantly from the last observed or broadcasted over ATIS. From the duty controller’s point of view, there was no significant change in weather conditions, so she did not inform the flight crew of the conditions over the aerodrome during final approach.

According to the flight crew, they were not affected by the prevailed light rainy condition and however, associated with the crosswind reversion from left to right, left roll input applied by PF, initiated a left roll dynamics and lead to an increased localizer deviation to left (The aircraft deviated to the left of the runway centreline).

Decision to continue landing without “go-around”

Before the aircraft flare-out (approximately 50ft RA) and noting that the aircraft was still drifting, the PM ( as the PIC) should call out “go-around”. The PIC stated the investigation team that he knew the aircraft was not aligned with runway centreline, but he observed that the PF had applied flight inputs to correct the mis-alignment. Further, both flight crew members were in perception that deviation from the extended runway centreline was still acceptable for safe landing.

The investigation team conducted a simulation test (on A330 flight simulator) applying the conditions prevailed during incident and it was observed that after realising the aircraft deviation to the left of centreline, flight crew had enough time to carryout safe go-around without continuing to land. As recommended in the FCTM for CONSIDERATION ABOUT GO-AROUND, failure to recognise the need and to execute go-around, is a major cause of approach and landing accidents/incidents.

Flight crew shall perform a go-around where the pilot feels uncomfortable or unsafe to continue the landing, especially if the aircraft is not on the correct glide path or localizer during the final approach (un-stabilized approach). According to the manufacture’s Safety First Article for Preventing Lateral Runway Excursions Upon Landing: Best Operational Practices, emphasized followings;

a. Be aware of the landing conditions,
b. Be go-around minded, as long as needed,
c. Be stabilized until the flare. If not, go-around,
d. As long as reversers are not selected, a go-around is always possible.

During post incident interview, both pilots confirmed that they didn’t consider go-around at any stage on final approach. The investigating team in the opinion that PM as PIC should have initiate the go-around with better situational awareness assessment which may hindered by Continuation Bias (the unconscious cognitive bias to continue with the original plan in spite of changing conditions).

Failure of leadership and crew resource management

The flight crew’s decision to continue landing without fully understanding situation does not accord with good cockpit resource management (CRM) practices. Pilots are trained to communicate openly and assertively. CRM training emphasizes teamwork and effective communication in the cockpit. Pilots are trained to work collaboratively and respect each other's opinions, promoting a culture where all crew members feel comfortable voicing concerns.

The PIC is directly responsible for safe operation of aircraft. In this incident, the PIC as the PM should have to voice out any safety concerns to PF and response immediately to deal with the situation. According to the CVR analysis, there was no any call out from the PM (‘Localiser’ or ‘centreline’ or ‘deviating left’) to remind the PF to align the aircraft with the extended runway centreline.

Pursuant to the Section 2.4 of Implementing Standard (SLCAIS) 026 issued in compliance with ICAO Annex 2, the PIC of an aircraft shall have final authority as to the disposition of the aircraft while in command. Therefore, PIC should maintain awareness of all aspects of his flight including the changing and dynamic flight environment in which he operates. Using SOP and CRM skills ensures that the procedures in place are followed in order to face every flight phase as predicated and minimize risk of errors, as well as mitigate any threat that might arise.

Investigation team in the opinion that poor situational awareness, ineffective communication, combine with cognitive biases of both flight crew had led to poor decision making. Further, maintain of lower authority gradient (democratic style) and/or inadequate leadership of PIC had led to his blurred responsibilities and slower decision making.

Flight crew failure to report incident

After the incident, the aircraft was taxied in and parked at the designated parking bay at VCBI by flight crew and during maintenance inspection duty technician had observed four tires of the left MLG had been damaged. Thereafter, an occurrence report was submitted by SriLankan Engineering to CAASL, but there was no pilot report available.

During investigation both flight crew were questioned regarding non reportage the incident and both pilots stated that they did not have any indication for any system failure during landing roll and during taxi and as they considered that it was a normal landing, they did not deem it necessary to report. However, both PIC and FO indicated that they were aware of the operator’s occurrence reporting requirement. This indicted that both pilots were on degraded situational awareness (unknowing the severity of incident) or intentionally evasion of reporting the incident.

Safety information that is provided from the flight crew has the potential to be highly descriptive and contextualised to the perspective of the front-line operator, aiding the identification and interpretation of hazardous conditions that may be present in the system.

The Investigating Team reviewed the Final Investigation Report issued by the Transport Safety Investigation Bureau of Singapore concerning a similar incident that occurred on 21st March 2019 at Changi International Airport involving an A320 aircraft operated by SriLankan Airlines. It was highlighted that, during that incident flight crew also had failed to report the incident and they did not deem it necessary to file an occurrence report.

Therefore, as a front-line operator, SriLankan Airlines should ensure a safe and open reporting culture withing organization by complying to regularity requirements since, each incident is a learning opportunity and an opportunity to improve safety in the operational environment.

Runway inspection after incident

After observing the damages to all four tyres on left MLG, SriLankan Engineering Department has informed Apron Control Supervisor regarding the incident. Approximately 0015 hrs (0545 Local), around 35 minutes after the landing, initial runway inspection was carried out on runway 22 touchdown area and no any observation were made. During this inspection they were limited to runway 22 touchdown zone (around runway 22 centreline) as they were informed of a suspected tyre burst had occurred during landing.

During the subsequent inspection approximately at time 0555 Local, they found that four runway edge lights on left side of runway 22 were damaged and some tyre derbies were on the edge of the runway 22 landing zone. The transmission of inaccurate information from the source (SriLankan Engineering Department), about the tyre damage, caused the inspection team to focus on a potential tyre burst, leading them to overlook Foreign Object Debris (FOD) during the initial inspection. Therefore, the damaged runway edge lights and tyre derbies posed a FOD hazard other aircraft used the runway 22 until it was detected.