Sky B732 at La Serena on Jul 18th 2012, touched down off runway, wing tip strike

Last Update: January 23, 2013 / 17:17:02 GMT/Zulu time

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Incident Facts

Date of incident
Jul 18, 2012

Classification
Incident

Aircraft Registration
CC-CRQ

Aircraft Type
Boeing 737-200

ICAO Type Designator
B732

Chile's Departamento Prevencion de Accidentes (CDPA) released their final report in Spanish concluding the probable cause of the accident was:

a non-stabilized approach to La Serena's runway 30 which led to the aircraft impacting the runway with its right hand wing.

Contributing factors were:

- the commencement of the approach without compliance with the procedures for visual approaches stated in aircraft operation manual and flight crew training manuals

- failure to go around despite the criteria for a stabilized approach were not met

The captain (ATPL, 24,887 hours total, no experience on type provided) was pilot flying for the sector, the first officer (CPL, 3,388 hours total) was pilot monitoring for the sector. The aircraft was descending towards La Serena's La Florida Aerodrome cleared direct to La Serena VOR on a heading of 310. Weather at La Serena was indicated at visibility of 7000 meters, cloud ceiling at 1500 feet, the Metars provided a visbility of 6000 meters with a cloud ceiling of 1000 feet. These conditions prevented an approach to runway 12, the captain therefore briefed for a visual approach to runway 30. The crew subsequently requested a visual approach to runway 30, ATC instructed to maintain visual reference with the ground at all times.

Upon contacting tower of La Serena the crew was advised visibility westward was 6400 meters with the cloud base at 600 feet, visibility eastwards was 10,000 meters or better. The crew was cleared for a visual approach to runway 30 and instructed to join a right hand downwind. While on the downwind, about 5.4nm from the VOR, the crew received clearance to land on runway 30.

The aircraft did not turn onto a base leg (90 degrees off runway heading) but turned to intercept the runway extended center line diagonally (about 45 degrees). During that leg (editorial note: the report names it "final approach" even though it appears to have been a combined base and final leg) the captain instructed to lower the flaps to 40 degrees. The CDPA stated that during the final approach the aircraft was never aligned with the runway. The aircraft descended through 518 feet AGL at a right hand bank angle of 22.5 degrees and a heading of about 250 degrees, at 283 feet AGL the aircraft was banked left at -15.7 degrees, over the threshold the aircraft was banked right again at 23 degrees, the vertical acceleration increased from 1.07G to 1.36G coinciding with the right hand wing tip and right hand flap actuator fairing hitting the ground about 140 meters past the runway threshold and 8.9 meters left of the runway center line, the traces visible over a length of 46 meters with the tracks of the flap fairing visible over a distance of 42 meters. The right hand main gear touched down on the left hand edge of the runway about 200 meters past the runway threshold, the track of the outboard right hand main gear tyre remaining visible for 55 meters.

At that point the landing was aborted and a go-around was initiated, the bank angle increased to 39.6 degrees to the right 4 seconds after the right wing tip first contacted the runway. After the gear ground marks stopped the scrape marks of the right wing tip appeared again on the runway surface, running over a distance of 112 meters and crossing the right hand edge of the runway. The aircraft became airborne again at a heading of 330 degrees about 200 meters later, the stick shaker briefly activated, however, the aircraft climbed out to safety. The crew initially considered to attempt another approach to runway 12, however, due to weather conditions the approach was still not possible and the crew decided to divert to Copiapo.

Enroute to Copiapo increased vibrations occurred at higher speeds, the aircraft therefore maintained a speed of 230 KIAS while enroute to Copiapo at FL125 under visual flight rules. The aircraft landed safely in Copiapo.

There were no injuries to the 115 passengers and 6 crew.

The aircraft received substantial damage, especially structural damage to the rear spar of the right hand wing, which suffered deformation and lost material. In addition to the wing spar damage the aircraft received: outboard tyre of right main gear was worn, cracks and deformation of the right hand wing tip and navigation light cover, detachment of lower wing tip panel, cuts and deformation of the upper right hand wing tip panel, cracks of rear outboard flap fairing and flap rail and cracks of flap actuator #8.

In post flight interviews the captain provided testimony to the CDPA stating that the aircraft turned base at about 1500 feet AGL, however, there were overcast stratos clouds ahead on the base leg and the valley was covered by mist. The captain therefore turned final early. The captain stated the criteria for a stabilized approach (including being aligned with the runway center line) correctly and gave testimony that according to his assessment the approach was stabilized, only minor corrections of the course were needed to acquire/maintain the final approach course. At about 70 feet AGL he lost visual reference with the runway due to a phenomen called "refraction" and when he regained visual reference he recognized they were left of the runway and went around. The stick shaker briefly activated, an engine thrust asymmetry occurred for about 5 seconds causing the aircraft to roll right. The captain never realised the aircraft had contacted ground at all.

The first officer stated in his post flight testimony, that the base leg was flown at an angle of about 60-70 degrees to the runway center line instead of the normal 90 degrees due to cloud cover ahead on the normal base leg. The first officer stated the stabilized approach criteria correctly too and stated, that descending through 500 feet AGL they were stabilized with flaps 40 set already. On short final there was a lot of refraction from the sun just past the runway, he lost view of the runway for about 2-3 seconds. He noticed that the aircraft had made contact but believed it was only the landing gear. Only after landing in Copiapo he realized the right wing tip was bent.

The tower controller reported that the aircraft had been instructed to join a right downwind and report 5DME. Upon receiving the report at 5DME the aircraft was cleared to land. The aircraft turned in approaching the runway center line in a diagonal and needed to turn just prior to touchdown to line up with the runway. Its wingtip apparently contacted ground with sparks visible, the controller saw the underside of the aircraft at that time and during the go-around. The controller thought an accident was imminent.

Ground witnesses outside the airport perimeter reported the aircraft was turning clockwise at an unusual track at unusual low altitude, then made a sharp right hand turn to align with the runway. They lost sight of the aircraft as it descended towards the runway and saw it reappear when it climbed out again. The approach was very unusual to any other aircraft that appeared aligned with the runway and on PAPIs way out.

Passengers reported that just prior to getting the runway in sight to their right the aircraft made a sharp right turn. The engines were at idle at that time, it appeared they touched down to the left of the runway, the engines accelerated and the aircraft climbed out. The captain announced about 5 minutes later the balked landing was the result of sun glare.

The CDPA analysed that the aircraft was never aligned with the runway. The aircraft had flown a base leg at 250 degrees instead of 210 degrees and approached the threshold at that heading, then made a sharp right hand turn to align with the runway centerline. The criteria for a stabilized approach were never met.

The CDPA further analysed that the testimony of the crew was not credible. Had the sunglare indeed caused the go-around, they would have been exposed to the sun glare during the entire stabilized approach along the extended runway center line. In addition, as soon as visual reference was lost with the runway a go-around should have been initiated. The flight data recorder did not confirm any thrust asymmetry.
Incident Facts

Date of incident
Jul 18, 2012

Classification
Incident

Aircraft Registration
CC-CRQ

Aircraft Type
Boeing 737-200

ICAO Type Designator
B732

This article is published under license from Avherald.com. © of text by Avherald.com.
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