Korean B739 at Osaka on Apr 9th 2018, tail strike on go around

Last Update: August 14, 2019 / 19:03:18 GMT/Zulu time

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Incident Facts

Date of incident
Apr 9, 2018

Classification
Accident

Airline
Korean Airlines

Flight number
KE-733

Departure
Jeju, South Korea

Destination
Osaka Kansai, Japan

Aircraft Registration
HL7725

Aircraft Type
Boeing 737-900

ICAO Type Designator
B739

Airport
Kansai International Airport, Osaka

Airport ICAO Code
RJBB

A Korean Airlines Boeing 737-900, registration HL7725 performing flight KE-733 from Jeju (South Korea) to Osaka Kansai (Japan) with 91 passengers, was on short final to Kansai Airport's runway 06L when the crew initiated a go around at very low height at 21:33L (12:33Z), the tail of the aircraft contacted the runway surface during the rotation for the go around. The aircraft climbed out, positioned for another approach to runway 06L and landed without further incident about 15 minutes after the go around. There were no injuries.

Japan's JTSB reported the aircraft sustained damage due to a tail strike on go around and reported the occurrence as an accident (which identifies the damage as substantial). An investigation has been opened.

Japan's Ministry of Transport reported the aircraft scraped its tail on the runway and went around. The aircraft received minor damage, mainly abrasion of paint from the belly, the occurrence was rated an accident (Editorial note: which contradicts the "minor damage"). Three investigators were dispatched on site.

The airline reported there were no major problems.

The occurrence aircraft was still on the ground in Osaka about 25 hours after landing.

On Aug 14th 2019 the JTSB released their final report concluding the probable causes of the accident were:

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.

The JTSB reported the aircraft performed an ILS approach to runway 06L. While maneouvering to intercept the localizer at 4000 feet the crew noticed a tail wind of about 30 knots. The captain (45, ATPL, 5,893 hours total, 216 hours on type), pilot flying, had memorized ATC wind indications they would have a slight crosswind component (winds from 030 degrees at 3 knots), winds would be almost calm on the threshold. Nonetheless, experiencing the strong tail wind the captain assumed they'd land with a tail wind component and thus decided to initiate the flare earlier than normal. The aircraft intercepted localizer and glideslope, the autopilot and autothrust was turned off at 1200 feet, and a fully stabilized approach occurred. At 30 feet AGL the captain pulled the thrust levers to idle and initiate the flare from about 2 degrees nose up pitch angle. The rate of descent increased, the captain attempted to arrest the descent by raising the nose, however to no avail. The first officer (33, CPL, 1796 hours total, 792 hours on type) felt the flare was insufficient and without callout pulled the yoke. The aircraft touched down at 1.87G and a pitch angle of 3.5 degrees nose up, spoilers began to deploy, the aircraft bounced however. The captain, unsure about the extent of the bounce, initiated a go around when the aircraft was at 5 degrees of nose up, the pitch increased to somewhere between 7 and 10 degrees nose up when the main gear touched down a second time, the aircraft finally climbed away at 10 degrees nose up. The first officer was still producing control inputs with the captain following those inputs. The aircraft positioned for another ILS approach to runway 06L and landed without further incident.

Both pilots did not recognize the tail had contacted the runway surface until scratch marks were found by ground personnel.

The JTSB analysed:

However, it is probable that initiation of the flare along with reduction of the engine thrust the Captain performed, assuming that the landing would be made in tailwind conditions, followed by insufficient raise of nose up made the descent rate higher than the Captain’s assumption. It is probable that the Captain was required to control the aircraft so as to cope with the changing wind conditions.

It is probable, at that moment, that the aircraft touched down when its attitude was changing to nose up direction because the FO, who felt that the descent rate was high, pulled the control column. It is probable that the aircraft bounced because it touched down when its descent rate was high and its attitude was being changed to the nose up direction.

It is highly probable that the Captain executed the go-around because the Captain was unable to predict the degree of bounce.

Both the POM and the FCTM prescribe that the lower aft fuselage contacts the ground at a pitch angle of 8.2 º or greater at the moment of the touchdown. The FDR records indicate that the pitch angle varied from approximately 7º to approximately 10º during the time from a second touchdown of the right main gear after initiating the go-around to the lifting off. During this period, 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 exceeding 8.2 º.

The Captain and the FO stated that the FO, who had noticed the high pitch angle after initiating the go-around, tried to restrict the movement of the control column uttering something to the Captain however, it was not possible to verify the words the FO had uttered in the CVR records.

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.

The training guide of the Company prescribes that a second touchdown should not be attempted to avoid if a go-around is executed after a high bounce, aircraft is not damaged as far as it maintains its attitude even if the second touchdown has occurred, and a pitch angle is to be verified with the PFD during the recovery.

It is somewhat likely that the Captain was unable to apply the training guide information and simulator training experience to actual situation even if he had received Bounced Landing Recovery training during the simulator training to promote to a captain.

Moreover, it is somewhat likely that the fact that the go-around was initiated when the attitude of the Aircraft was changing by the nose up maneuver immediately before the touchdown and the spoilers were deploying contributed to the excessive pitch angle.

At the time of occurrence of this accident, it is probable that the FO, who was the PM, judged the descent rate after initiating the flare was large and subsequently pulled the control column immediately before the touchdown without a call-out to avoid the hard landing.

The FOM of the Company prescribes that PM calls out the situations to PF in case that aircraft has deviated or will possibly deviate from a flight path, and in case of no response from PF, PM takes appropriate actions including taking over.

It is probable that the FO should have called out “FLARE” or “GOAROUND” at first at the very moment the FO noticed that the descent rate after the Captain had initiated the flare was large as prescribed in the FOM and the POM considering it is somewhat likely that ambiguity over either PF or PM is operating independently could lead to a possible threat to the safety of the flight if PM intervened an operation without a call-out as in the case like this accident.

Metars:
RJBB 091400Z AUTO 06003KT 9999 SCT050 OVC060 12/09 Q1020 NOSIG=
RJBB 091330Z 05003KT 9999 FEW030 SCT045 13/09 Q1020 NOSIG=
RJBB 091300Z 02004KT 9999 FEW030 BKN045 13/08 Q1020 NOSIG=
RJBB 091230Z 01003KT 9999 FEW030 BKN045 13/08 Q1020 NOSIG=
RJBB 091200Z 05003KT 9999 FEW030 BKN045 13/09 Q1019 NOSIG=
RJBB 091130Z 14003KT 9999 FEW030 BKN045 13/10 Q1019 NOSIG=
RJBB 091100Z 16003KT 9999 FEW030 SCT045 13/09 Q1019 NOSIG=
RJBB 091030Z 00000KT 9999 FEW030 BKN045 14/06 Q1018 NOSIG=
RJBB 091000Z VRB02KT 9999 FEW030 BKN045 13/08 Q1018 NOSIG=
RJBB 090930Z VRB02KT 9999 FEW030 BKN045 BKN/// 14/07 Q1018 NOSIG=
RJBB 090900Z 04002KT 9999 FEW030 SCT045 BKN/// 13/09 Q1018 NOSIG=