Skymark B738 at Tokyo on Aug 29th 2020, bird strike
Last Update: April 14, 2022 / 19:38:05 GMT/Zulu time
Incident Facts
Date of incident
Aug 29, 2020
Classification
Accident
Cause
Bird strike
Airline
Skymark Airlines
Flight number
BC-21
Departure
Tokyo Haneda, Japan
Destination
Fukuoka, Japan
Aircraft Registration
JA73NM
Aircraft Type
Boeing 737-800
ICAO Type Designator
B738
A post flight inspection revealed damage to the aircraft skin on the left hand side and internal structures. Japan's Ministry of Transport rated the occurrence an accident, on Sep 1st 2020 Japan's JTSB opened an investigation stating the aircraft received "skin damage" as result of the bird strike at 3300 meters about 15km (8 nm) southeast of the airport.
The occurrence aircraft was still on the ground in Fukuoka about 80 hours (3 days and 8 hours) after landing.
On Aug 27th 2021 the JTSB released a progress report in Japanese stating the first officer was pilot flying, the captain pilot monitoring. Climbing through 8500 feet the crew heard an impact sound near the lower left of the cockpit and an unusual odour developed in the cockpit. The crew checked all indications and instruments with no anomaly found and therefore decided to continue the flight to destination.
On Apr 14th 2022 the JTSB released their final report concluding the probable cause of the accident were:
In this accident, the JTSB concludes that it is highly probable that the aircraft collided with the bird in take-off climb from Tokyo International Airport and sustained damage to the airframe at an altitude of 8,500 ft over approximately 17 km east-northeast of the airport.
The JTSB analysed:
From the impact sound in the left lower part of the captain seat at an altitude of 8,500 ft over approximately 17 km east-northeast of Tokyo International Airport while the aircraft was in takeoff-climb from the airport, the substance that was seemingly a bloodstain adhered to the left side of the nose of the aircraft and dents in the surrounding outer skin found in postflight inspection of the airframe, the JTSB concludes that it is highly probable that the airframe was damaged by the collision with the bird at the relevant portion at this moment. The abnormal smell transitorily felt after the impact sound is probable to have been a stink, which generated when fragments of the bird were sucked into the compression of the left engine and heated, penetrated the aircraft.
The captain and FO are highly probable to have been unable to maneuver for avoidance since they were not aware of approach of the bird.
Besides, the altitude of 8,500 ft is high as birds fly at and birds climb higher than normal in some cases depending on species of birds and weather conditions.
(2) Response by flight crew
The JTSB concludes that it is probable that flight crew decided to continue the flight based on their judgement that there probably occurred a bird strike and it did not hinder the flight after having confirmed that abnormal indication of instruments and vibration of the aircraft did not occur after occurrence of the impact sound and abnormal smell. Considering possible damage to the airframe at that time, the cruising altitude is probable to have been lowered than originally planned and flight speed set at the speed for passing through turbulence so that transition to the safety altitude could promptly be made in case of emergency and the load to the airframe structure in cruising mitigated.
By lowering the cruising altitude, the time for the aircraft to descend to the safety altitude (10,000 ft) in case of emergency was shortened by 46 seconds from approximately 3 minutes 48 seconds to approximately 3 minutes 2 seconds, given the maximum descent rate feasible to be set in onboard instruments (minus 7,900 fpm), and the differential pressure the aircraft received reduced by 0.55 psid from 8.35 psid to 7.80 psid.
(3) The species of the bird collided From the result of the numeric simulation performed by the NTSB, the JTSB concludes that it is possible that the bird weighing between 1.8 kg and 3.6 kg collided. On the other hand, all residues adhered to the airframe were wiped out and discarded to verify the conditions of the damage after the mechanics of the company had confirmed the traces of the bird strike in examining the airframe after arrival at Fukuoka Airport. Due to this, the species of the bird could not be identified. It is possible that the supposed species of the bird was a hawk family or heron family from the possible weight between 1.8 kg and 3.6 kg and the accident site.
Incident Facts
Date of incident
Aug 29, 2020
Classification
Accident
Cause
Bird strike
Airline
Skymark Airlines
Flight number
BC-21
Departure
Tokyo Haneda, Japan
Destination
Fukuoka, Japan
Aircraft Registration
JA73NM
Aircraft Type
Boeing 737-800
ICAO Type Designator
B738
This article is published under license from Avherald.com. © of text by Avherald.com.
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