Accident Boeing 737-9B5 HL7725,

ASN Wikibase Occurrence # 319688

Date:	Monday 9 April 2018
Time:	21:33
Type:	Boeing 737-9B5
Owner/operator:	Korean Air
Registration:	HL7725
MSN:	29999/1512
Year of manufacture:	2004
Total airframe hrs:	30740 hours
Engine model:	CFMI CFM56-7B24
Fatalities:	Fatalities: 0 / Occupants: 99
Aircraft damage:	Substantial, repaired
Category:	Accident
Location:	Osaka-Kansai International Airport (KIX) - Japan
Phase:	Landing
Nature:	Passenger - Scheduled
Departure airport:	Jeju (Cheju) International Airport (CJU/RKPC)
Destination airport:	Osaka-Kansai International Airport (KIX/RJBB)
Investigating agency:	JTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Korean Air Lines' flight 733, a Boeing 737-9B5, suffered a tail strike accident on runway 06L at Osaka-Kansai Airport, Japan, when the flight crew were commencing a go-around due to bouncing. The plane landed safely at the second approach 15 minutes later. No personal injuries were reported.
The aircraft departed Jeju, South Korea at 20:24 hours with the captain as Pilot Flying on the leg to Osaka-Kansai. The landing briefing commenced at around 20:59 prior to the descent did not include information regarding a tailwind at the time of the landing.
As the aircraft had commenced the ILS approach to runway 06L, the controller reported wind from 030° at 3 kt. Both the autopilot and the auto-throttle of the aircraft were disengaged at around a radio altitude of 1,200 ft. In addition, the aircraft continued a stabilized approach. The captain, who was assuming that a landing would be made with a tailwind component, planned to put the thrust levers to their idle position earlier than usual when performing a flare in order to prevent that a touchdown would be long down on the runway.
At around 21:32:54, the captain moved the thrust levers to their idle position along with initiating the flare at 2° pitch angle at a radio altitude of about 30 ft. Although the captain tried to continue raising the nose and to reduce the rate of descent, the timing of such maneuvers was slightly delayed. Reducing the rate of descent was infeasible because the thrust levers had already been set to their idle position. The captain tried to reduce the rate of descent of the aircraft by pulling the control column further.
The first officer, who felt the rate of descent was large, pulled the control column to reduce the rate of descent without making any call-out. Having noticed the operation of the FO, the captain kept the control column so as to follow the FO's operation.
At around 21:32:57, the right main landing gear of the aircraft touched down at pitch angle of about 3.5°, and all spoilers began to deploy when the auto speed brake was activated.
Subsequently, after the left main landing gear had touched down, the aircraft bounced. The maximum vertical acceleration recorded in the FDR during this period was 1.87 G.
The captain, who was unable to predict the degree of the bounce and assumed that the impact accompanied by the touchdown after the bounce would be hard, executed a go-around maneuver. The pitch angle of the aircraft immediately before executing the go-around was about 5°. The aircraft started climbing positively at about 10° pitch angle after its both main landing gears touched down again approximately one second after it had executed the go-around.
The aircraft landed on runway 06L conducting the ILS approach again after flying in accordance with the missed approach procedure.
Both the flight crew members did not recognize that the aircraft had struck the runway until the scratch marks were found on the lower aft fuselage by mechanics after the aircraft arrived at the allotted parking spot. The scrape mark on the runway was 15 meters long.

PROBABLE CAUSES
In this accident, it is highly probable that the lower aft fuselage of the aircraft was damaged with contacting the runway because its pitch angle became too high during the go-around following the bounce at the time of the landing.
Regarding the pitch angle became too high, it is somewhat likely that because the Captain, who thought the impact after the bounce would become hard and tried to avoid the second touchdown, performed large nose up maneuver.

METAR:

12:30 UTC / 21:33 local time:
RJBB 091230Z 01003KT 9999 FEW030 BKN045 13/08 Q1020 NOSIG=

Accident investigation: