China Airlines A333 at Taipei on Jun 14th 2020, all primary computers, reversers and autobrakes failed on touchdown
Last Update: September 3, 2021 / 14:01:55 GMT/Zulu time
Date of incident
Jun 14, 2020
Shanghai Pudong, China
Taipei Songshan, Taiwan
ICAO Type Designator
Airport ICAO Code
The aircraft remained on the ground until Jun 23rd 2020, then positioned to Taipei's Taoyuan International Airport and is on the ground there since.
Taiwan's CAA reported the root cause of the occurrence is still under investigation and advises all A330 operators to take countermeasures:
- prior to dispatch consider possible deceleration deficiencies with the conditions mentioned above on wet runways.
- required landing distance shall be predetermined for a wet runway, if the distance is a concern consider an alternate aerodrome
- operators should enhance crew awareness of wet runway operations, if automatic braking is out of function promptly change to the alternate system or apply manual braking
On Sep 3rd 2021 Taiwan's ASC released their final report in Chinese and their English Executive Summary concluding the probable causes of the incident were:
Findings related to probable causes
1. The three flight control primary computers (FCPCs) of the occurrence aircraft became inoperative almost at the same time during touchdown. The root cause was determined to be an undue triggering of the rudder order COM/MON monitoring concomitantly in the 3 FCPC. At the time of the aircraft lateral control flight law switching to lateral ground law at touch down, the combination of a high COM/MON channels asynchronism and the pilot pedal inputs resulted in the rudder order difference between the two channels to exceed the monitoring threshold. The FCPC1 failed first.
2. After the FCPC1 failure, the master control of flight control system was handed over to FCPC2 and FCPC3 in sequence whose asynchronism were also high at that moment; thus eventually all three FCPCs became inoperative. As a consequence of the three FCPCs loss, the thrust reversers, the ground spoilers, and the autobrake system were lost, resulting in an increased landing distance for the aircraft.
Findings related to risk
1. During landing, flight controls reconfigured from normal law to direct
law after all three flight control primary computers (FCPCs) became inoperative. While all aircraft primary control surfaces were still controllable, the deceleration devices including ground spoilers, thrust reversers, and autobrake were lost, the deceleration of aircraft was relied on manual brake by the pilots.
2. Given all three flight control primary computers (FCPCs) failed seconds after touchdown, should other factors (long flare, runway state, ¡) have affected the landing distance, the aircraft could have overrun the runway even if the pilots had immediately applied maximum manual brake after realizing the autobrake had failed.
1. The occurrence flight crew were properly certificated and qualified in accordance with the requirements of the Civil Aviation Authority of Taiwan. Records of training and checks have no anomaly related to this occurrence operation. The rest and activities of flight crew 72 hours before the occurrence were normal. No evidence indicated any pre-existing medical conditions or alcohol that might have adversely affected the flight crew¡¯s performance during the occurrence flight.
2. During the approach, flare, landing, and roll out until aircraft came to a full stop, the actions performed by the flight crew complied with stable approach and manual landing Standard Operation Procedures (SOP) prescribed in Flight Crew Operating Manual (FCOM).
3. During the landing roll, the crew kept good interaction and high situation awareness based on pilot-flying¡¯s response to decelerating the aircraft and pilot-monitoring's call out of relevant abnormal system status.
4. With three FCPCs inoperative, actual remaining runway distance (30 feet margin) of the occurrence flight was shorter than the calculated value (172 feet margin), possibly due to tailwinds, runway conditions, and manual braking as these factors might increase the braking distance.
5. Ground spoilers function requires at least one functional FCPC, arming autobrake requires at least two functional FCPCs, deployment of thrust reversers require unlock signal from either FCPC1 or FCPC3. As a consequence of the three FCPCs loss, the non-release of the independent locking system prevented the reversers¡¯ deployment, the ground spoilers were cancelled and autobrake system was lost.
6. Shop finding of FCPC1 indicated that the unit is no fault found (NFF). The built-in test (BITE) shows SAO£¨Sp¨¦cification Assist¨¦e par Ordinateur£©fault at the time of the triple FCPC fault. The SAO fault corresponds to the fault was trigged during COM/MON monitoring rather than the fault of computer hardware.
7. Following the occurrence, Airbus reviewed its in-service experience, and confirmed that no other triple PRIM fault at touchdown event had been reported on A330/A340 aircraft family since entry into service. The A330/A340 fleet fitted with electrical rudder has accumulated 8.7 millions of Flight Cycles and 44.3 millions of Flight Hours (in-service data from April 2020).
8. The runway surface friction, longitudinal slope, transverse slope, and longitudinal slope changes of the Songshan Airport runway 10 complied with relevant standards.
9. The deceleration performance of the occurrence flight between 6,600 feet and 7,300 feet from the threshold of runway 10 deteriorated. It may be due to paint marking and rubber deposit on the touchdown zone of runway 28.
10. The occurrence flight first touchdown and second touchdown were about 1,500 feet and 1,800 feet respectively with respect to the runway threshold. The touchdown points were both located at runway touchdown zone.
11. After the flight crew applied manual braking, the overall deceleration performance was between ¡°medium¡± and ¡°good¡± level consistent
with the reported wet condition of the runway, which should be able to rule out the effect of hydroplaning.
The ASC summarized the sequence of events:
The aircraft took off at 1625 with the captain as the pilot flying (PF) and the co-pilot as the pilot monitoring (PM). During descent, the flight crew received the information L from automatic terminal information system (ATIS), and was instructed to use the instrument landing system (ILS) of runway 10. After calculating the landing performance, the Electronic Flight Bag (EFB) showed that there would be 362 feet runway distance remaining if autobrake was set at low.
During the descent and approach phases, no abnormalities were found. About six minutes before landing, the PF was alerted about the rain near Songshan Airport, he asked the PM to review the latest weather information, and learned that the tail wind blew from 280 degrees at 6 knots with a light thunder shower rain. Runway 10 was in use.
At 1743:21, during the final approach, the airplane was at the barometric altitude of about 3,008 feet, the flight crew was informed by the tower that the visibility at the airport had dropped to 2,500 meters.
At 1743:51, the airplane was at the barometric altitude of about 2,480 feet, the tower issued a landing permission: "dynasty 202 runway 10 wind 250 degrees 9 knots caution tail winds clear to land." About fifteen seconds later, the PF reminded the PM, "call out when spoilers deploy so I can tell if the main gear has touched down."
At 1744:37, the airplane was at the barometric altitude of about 1,832 feet, the flight crew conducted landing checklist and the PF asked the PM to set the autobrake from low to medium due to the weather change at Songshan Airport.
At 1745:41, the airplane was at the radio altitude of about 996 feet, the tower reminded that wind speed was 10 knots. Six seconds later, the radio altitude was 919 feet, and the PF said "the wipers can be faster, it's okay", the PM answered "it¡¯s at the fastest speed already".
At 1745:58, the airplane was at the radio altitude of about 773 feet, the PM reported ¡°approach lights ahead¡± and the PF then disengaged the autopilot to continue the approach.
At 1746:41, the airplane was at the radio altitude of about 136 feet, the PM reminded the PF ¡°center line¡± to maintain on track.
Seven seconds after the aircraft passed the radio altitude of 60 feet, at 1746:54, the aircraft touched down at between 1,500 and 2,000 feet from runway 10 threshold with pitch up about 4.2 degrees, roll to the right at about 1.1 degrees, and its magnetic heading at about 94 degrees. The ground speed was 147 knots (indicated airspeed was 135.5 knots) and the maximum vertical acceleration was 1.28g's. The slats/flaps configuration was FULL. Ground spoilers (i.e. spoilers 2 to 6) started to deploy.
One second after the touchdown, the PM immediately called out ¡°spoilers¡±, while the left and right main gear shifted between air mode and ground mode for about 0.75 seconds and 0.5 seconds respectively. Three seconds after the main gear touched down, autobrake system fault was recorded on FDR. One second later, PRIM1/PRIM2/PRIM3 faults were recorded at the same time and the spoilers retracted, as the ground spoiler function was lost. The PM called out ¡°reverse¡± and the nose gear touched ground at the same time. After that, the nose gear flipped between air mode and ground mode for nearly 7 seconds.
At 1746:59, the PF asked twice if ¡°autobrake is on¡± (the ground speed was 141 knots). The PM answered, ¡°autobrake is not on¡±. About five seconds later (1747:04), the PF called out ¡°manual brake¡±, and applied full brake pedal. The normal brake hydraulic pressure value was 448 psi and longitudinal acceleration rate value was about -0.1g, indicating a deceleration.
At 1747:07, the PM called out "reverse no green", about one second later, the PF requested to his first officer ¡°quickly help me brake help me brake¡± (the ground speed was 127 knots at this time), from then on, both pilots applied full pedals on the brakes manually, the normal brake pressure was up to 576 psi and the longitudinal acceleration rate was -0.14g 's.
Until 1747:36 when the aircraft came to a full stop at 30 ft before the end of the runway, the aircraft brake pressure and longitudinal acceleration rate fluctuated from 128 psi to 2,560 psi and from -0.05g's to -0.47g's respectively during this period.
RCSS 141100Z VRB02KT 8000 -SHRA FEW006 FEW016CB SCT025 BKN045 26/26 Q1013 RETSRA NOSIG RMK CB S A2992 RA AMT 17.6MM=
RCSS 141044Z VRB02KT 6000 -SHRA FEW008 FEW016CB BKN025 BKN045 26/26 Q1012 RETSRA NOSIG RMK CB S A2991=
RCSS 141036Z VRB02KT 3000 TSRA FEW008 FEW010CB BKN016 BKN035 26/26 Q1012 BECMG 5000 NSW RMK TS S AND N MOV E A2991=
RCSS 141030Z VRB03KT 1200 R10/1300U +TSRA FEW006 FEW008CB BKN014 BKN025 26/26 Q1012 TEMPO 3000 RMK TS OVHD A2991=
RCSS 141009Z 23006KT 200V270 0800 R10/1500D +TSRA FEW004 FEW008CB BKN010 OVC025 26/26 Q1013 TEMPO 3000 RMK TS OVHD A2992=
RCSS 141000Z 25008G19KT 200V280 1000 R10/1300D +TSRA FEW006 SCT010CB BKN012 BKN025 27/26 Q1012 TEMPO 3000 RMK TS OVHD A2991 RA AMT 18.2MM=
RCSS 140949Z 25008G19KT 210V270 1000 R10/1500D TSRA FEW006 FEW010CB BKN012 BKN030 27/26 Q1012 TEMPO 3000 RMK TS OVHD A2990=
RCSS 140945Z 26008KT 220V280 1200 R10/1800D -TSRA FEW006 FEW012CB BKN014 BKN030 28/27 Q1012 TEMPO 3000 RMK TS S STNR A2989=
RCSS 140941Z 26007KT 2500 -TSRA FEW008 FEW014CB BKN016 BKN040 28/27 Q1012 BECMG 1500 TSRA RMK TS S STNR A2989=
RCSS 140937Z 28006KT 250V320 4000 -TSRA FEW008 FEW016CB BKN018 BKN040 28/27 Q1012 BECMG 3000 TSRA RMK TS S STNR A2989=
RCSS 140930Z 29005KT 260V320 7000 -TSRA FEW008 FEW016CB BKN020 BKN045 29/27 Q1012 BECMG 3000 TSRA RMK TS S STNR A2989=
RCSS 140907Z 26004KT 230V290 7000 -TSRA FEW012 FEW016CB BKN025 BKN045 29/27 Q1011 BECMG 3000 TSRA RMK TS OVHD A2988=
RCSS 140900Z 28003KT 260V320 7000 -TSRA FEW014 FEW018CB BKN025 BKN060 29/27 Q1011 BECMG 3000 TSRA RMK TS SW MOV N A2987 RA AMT 2.2MM=
RCSS 140857Z 28003KT 260V320 7000 -TSRA FEW014 FEW018CB BKN025 BKN060 29/27 Q1011 BECMG 3000 TSRA RMK TS SW MOV N A2987=
RCSS 140839Z VRB03KT 6000 VCTS -SHRA FEW014 FEW018CB BKN020 BKN050 29/27 Q1011 BECMG 3000 TSRA RMK TS S MOV NE A2986=
RCSS 140830Z 15003KT 090V210 7000 -SHRA FEW014 FEW018CB BKN025 BKN050 29/27 Q1011 RETS RESHRA NOSIG RMK CB S-SW A2987=
RCSS 140812Z VRB02KT 6000 SHRA FEW014 FEW016CB BKN020 BKN035 29/27 Q1011 RETS NOSIG RMK CB S A2986=
RCSS 140800Z 28004KT 250V320 7000 VCTS -SHRA FEW014 FEW018CB BKN025 BKN040 30/27 Q1011 NOSIG RMK TS SE MOV NE A2986 RA AMT 0.2MM=
RCSS 140755Z 29004KT 260V320 7000 VCTS -SHRA FEW016 FEW020CB BKN025 BKN040 30/27 Q1011 NOSIG RMK TS SE MOV NE A2986=
RCSS 140747Z 30005KT 270V330 8000 VCTS FEW018 FEW020CB BKN028 BKN040 31/27 Q1011 NOSIG RMK TS SE MOV NE A2986=
RCSS 140730Z 30004KT 270V340 8000 VCSH FEW018 BKN030 BKN050 30/27 Q1011 NOSIG RMK A2986=
RCSS 140721Z 30005KT 270V330 8000 VCSH FEW018 BKN030 BKN045 30/27 Q1011 NOSIG RMK A2986=
RCSS 140700Z 29004KT 240V330 7000 -SHRA FEW018 BKN030 BKN045 29/27 Q1011 NOSIG RMK A2986 RA AMT 4.6MM=
Date of incident
Jun 14, 2020
Shanghai Pudong, China
Taipei Songshan, Taiwan
ICAO Type Designator
Airport ICAO Code
This article is published under license from Avherald.com. © of text by Avherald.com.
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