Summary
The prevailing weather information reported rain overhead the station with a visibility of 3,000m. The incident occurred after sunset.
The crew executed a missed approach from the first approach, an ILS on runway 18L, at an altitude of about 500ft due a crosswind component ranging from 38–45 kt displayed on the FMC. The investigation believes that the decision to carry out a missed approach with the prevailing weather conditions at that time was good airmanship and in the best interest of safety.
The crew thereafter requested for 18R with ATC weather information reporting wind at 090/15kt (15kt crosswind component) with a visibility of 3,000m in moderate rain.
The F/O (2,018hrs TT) was PF. The crew stated that the second approach was stable but just before touchdown, visibility reduced due to heavy rain. The autopilot was disengaged at 83ft RA when the aircraft was on ILS approach.
The throttles were closed at 10ft, for landing. The aircraft touched down right of the runway centreline, which became worse on deployment of thrust reversers, and veered into the grass verge. The Captain (16,740hrs TT) took control of the aircraft and brought it back to the runway.
The FDR plots did not capture the thrust reverser parameters but showed inputs from the rudder pedals and corresponding rudder deflection, which was significant at touchdown point, indicating that the handling of the aircraft was contributory to the aircraft veering further right of the runway centreline.
The FDR plots also showed that the PF applied the rudder pedals prior to touchdown - the PF began a right rudder command input, likely to initiate a de-crab manoeuvre. Shortly after touchdown the PF’s right rudder command reached 11.2 degrees to the right of the datum with an associated deflection of 25.8 degrees of the aircraft rudder to the right which corresponds to the aircraft veering to the right of the runway centreline and excursed into the grass verge.
The aircraft was taxied to the apron. After engine shutdown, the crew conducted a walk-around inspection and discovered deep cuts, dents and abrasions to the No. 1, No. 2 and No. 4 MLG tyres as well as No.1 Nose Gear tyre. There were also grass ingestions into the right MLG wheel well, right MLG wheel axle and right inboard flap tracks. There were no injuries.
The incident was neither reported to the ATC nor entered in the Technical Log Book as required by relevant regulations. The CVR was also overwritten.
Causal Factor:
Excessive rudder application by the crew after touchdown.
Contributory Factors:
- Reduced visibility due heavy rain on touchdown.
- The decision to continue approach in an unfavourable weather condition with crosswind component of 090o/15kt.
Photo of cuts and flat spots/abrasion on No. 2 main wheel tyre
The full report is available here:
https://aib.gov.ng/wp-content/uploads/2020/11/Final-Report_Aero-5N-BLG.pdf |
5N-BLG 737-500 Runway Excursion on Landing
