Capital Beijing A320 at Macau on Aug 28th 2018, dropped nose wheels on hard touchdown (3.406G)
Last Update: April 4, 2019 / 15:20:29 GMT/Zulu time
Incident Facts
Date of incident
Aug 28, 2018
Classification
Accident
Airline
Capital Airlines Beijing
Flight number
JD-5759
Departure
Beijing, Macau
Destination
Macau, Macau
Aircraft Registration
B-6952
Aircraft Type
Airbus A320
ICAO Type Designator
A320
Runway 34 was closed for about 3 hours until the aircraft was moved off the runway. Runway 15/33 remained operational.
The missing wheels were recovered from Macau's runway.
China's CAAC reported the aircraft attempted landing at Macau at 11:16L (03:16Z) but was unsuccessful, the crew went around. The crew declared Mayday and requested emergency services on standby in Shenzhen reporting possible landing gear failure. The aircraft landed on Shenzhen's runway 34 at 11:58L (03:58Z), it was subsequently found both nose wheels were missing. The aircraft was evacuated. 5 Passengers were taken to a hospital with minor injuries. Shenzhen's runway 34 was temporarily closed. The CAA Shenzhen have opened an investigation into the occurrence.
The airline reported the aircraft is suspected to have encountered windshear while landing at Macau, the crew immediately initiated a go around, suspected damage to the landing gear and declared emergency. The aircraft diverted to Shenzhen where the 157 passengers and 9 crew were evacuated.
On Aug 29th 2018 The Aviation Herald received information from a multitude of sources stating that the aircraft touched down on Macau's runway 34 at 7.7 degrees nose up, 123 KIAS and 2.4G, bounced, touched down a second time at 15.1 degrees nose up between 133 and 144 KIAS and 3.4G. The aircraft bounced again, touched down a third time at 7.7 degrees nose down (nose gear first), both wheels and part of the nose gear structure separated, debris was ingested by the left hand engine, debris destroyed the VHF1 antenna (causing temporary loss of communication), the damage to the nose gear also prompted the nose gear to permanently indicate being on the ground preventing gear retraction. About 5 seconds after the third bounce the go around was initiated.
On Sep 7th 2018 Macau's CAA reported the aircraft sustained damage to its nose gear and left main landing gear on a hard touchdown in Macau. The occurrence was rated a serious incident (editorial note: ??) and is being investigated.
On Sep 8th 2018 The Aviation Herald received a passenger photo taken from the bus in Shenzen, which shows part of the underside of the tail section of the aircraft, no damage visible in that area.
On Nov 30th 2018 Macau's CAA released their preliminary report summarizing the sequence of events:
The flight was normal until final approach. As the aircraft was in final stages of the approach and descending from 50 to 30 feet above ground level, the indicated airspeed decreased from 134 to 122 knot and the rate of descent was about 688 feet/min. The airspeed decrease occurred within 1-2 seconds and by touchdown the aircraft was being affected by a 28 knot tailwind.
At 03:15:35, the aircraft touched down on the main landing gear with peak vertical acceleration 2.359G at about 300 meter after the threshold of runway 34 at Macau International Airport and bounced up in the air.
At 03:15:39, the aircraft touched down again on the nose landing gear with peak vertical acceleration 3.406G at about 600 meter after the threshold of runway 34. The nose landing gear was damage and debris were ingested into both engines, resulting both engines were damaged.
After the second touchdown, the captain conducted miss approach procedures with low climb rate.
At 03:16:21 Macau Air Traffic Control (ATC) informed the flight crews that fire was observed coming out from its left engine.
At around 03:20:00, a tire was found on the Macau runway and flight crews were informed.
The captain declared mayday and determined suitable airport to land the aircraft, navigation system was inoperative after the hard landing and backup navigation system was activated.
After evaluating the situation, flight crew decided to divert to Shenzhen and requested full emergency landing at Shenzhen Bao’an International Airport.
At 03:57:52, the aircraft landed in Shenzhen Bao’an International Airport. The Aircraft sustained substantial damage and there was no outbreak of fire.
The crews activated emergency evacuation procedures and all persons onboard were evacuated through evacuation slides from door 1 right and door 4 right.
5 passengers received minor injuries as result of the evacuation.
The aircraft received substantial damage to the nose landing gear strut as well as structural damage to the fuselage, severe damage to the left hand engine (melted metal in high pressure compressor and high pressure turbine, all fan blades damaged, low pressure compressor damaged by foreign objects, minor damage to the right hand engine (6 fan blades damaged, low pressure and high pressure compressor blades damaged within AMM limitations, 2 acoustic panels damaged, nicks at the engine inlet), some damage to the left main landing gear, the aft fuselage and APU drain mast.
Raw data of the wind sensor at the airport revealed there were sudden wind gusts of 22 knots from 170-190 degrees (tail wind).
On Apr 4th 2019 Macau's CAA (MCAA) released their final report concluding the probable causes were:
Findings
The flight was uneventful up to the final approach stage into Macau International Airport.
Momentarily prior to the first touchdown, the aircraft experienced severe lowlevel wind shear with rapid tailwind increase and downdraft tendency, which led to the reduction of airspeed and lift, resulting in the higher-than-usual vertical acceleration at the first touchdown.
Macau International Airport had no equipment to detect low-level wind shear, hence there was no low-level wind shear information about runway 34 was provided to the JD5759 pilots at landing.
According to recorded flight data, no wind shear alarm was triggered.
The aircraft main landing gear touched down (first touchdown) with a rate of descent of 640 feet/min resulting in a vertical acceleration of 2.36G.
At the first touchdown the thrust lever was not retarded to idle but moved to above the CLIMB detent (between MCT and TOGA detent) which was in contrary to the SOP. This prevented the activation of the Phased Lift Dumping (PLD) function.
The aircraft bounced and lifted-off again after the first touchdown for 4 seconds, reaching a maximum height of 7 feet.
During the bounce lift-off, the forward side-stick input was applied for about 7 seconds commanding a nose down pitch at varying amplitude.
The aircraft was not maintained at a normal landing attitude during the bounce.
The thrust levers were moved to idle during the bounce, this resulted in the activation of the ground spoiler by the PLD function even when the aircraft was actually airborne (due to the memorization of the ground condition for 3 seconds).
At the second touchdown, all three landing gears touched down within the same second with an attitude of -1.8 degree (nose down) and resulted in a vertical acceleration of 3.41G. The nose landing gear wheels were fractured as a result.
At the go-around, the aircraft experienced a tail strike.
The thrust lever of the Engine #2 was moved to the idle position despite the air traffic controller notified the pilots of observing fire coming out from Engine #1.
The aircraft could not maintain positive rate of climb during the go-around climb, triggering the stall warning twice which lasted for 2 and 9 seconds respectively. This led to a loss of 419 feet of altitude, reaching a lowest altitude of 627 feet RA before positive rate of climb was re-established.
Contributing factors
First touchdown at 2.36G and bounce
- Encountered severe low-level wind shear with rapid tailwind increase and downdraft tendency momentarily before touchdown
- Macau International Airport had no equipment to detect low-level wind shear.
- The aircraft landed with excessive tailwind.
Second touchdown at 3.41G with nose landing gear
- A normal landing pitch attitude was not maintained after the bounced landing.
- The thrust levers were moved to idle from above the CLIMB detent during the bounce, this resulted in the activation of the ground spoiler by the PLD function even when the aircraft was actually airborne (due to the memorization of the ground condition for 3 seconds).
The MCAA analysed that the flight was uneventful until descending through 500 feet AGL on approach to Macau. The aircraft crossed 500 feet AGL at 10 knots tailwind, the permitted limit, and was stabilized.
At 370 feet AGL the autopilot was disconnected. Descending through 100 feet AGL the tail wind began to continually increse reaching 27 knots at 5 feet AGL. "The tailwind increased from 9 knot at 100 feet RA to the peak of 27 knot at 5 feet RA within 12 seconds (increased by 18 knot within a vertical displacement of 95 feet within 12 seconds), which is categorized as severe low-level wind shear (over 12 knot of wind speed change within a vertical displacement of 100 feet)."
The MCAA analysed that the speed over ground remained almost constant at 150 knots, the indicated airspeed however reduced from 139 to 119 KIAS. The pilot monitoring (First Officer) should have called out the speed deviation (Vapp=139 KIAS), however, no such call was made.
The MCAA wrote: "the wind at the surface varied rapidly in both direction and strength to 22 knot at 189 degree (20 knot tailwind and 9 knot crosswind) momentarily before the aircraft’s first touchdown. The pilots were not notified of such an abrupt change in surface wind by the Macau Tower. The lack of low-level wind shear detection system at the Macau International Airport contributed to the failure of identifying such abrupt wind change. Although the onboard calculated wind display could be made reference to as an additional source of wind direction and strength reference close to the surface level (indicating tailwind in excess of 10 knot at 200 feet RA and below, and increasing), there was no evidence this additional wind reference was used by the pilots to make themselves become aware of the abrupt wind change and possible tailwind exceedance close to and at the surface. ... As the airspeed decreased rapidly from around 139 knot to 119 knot momentarily before touchdown due to the increasing strength of tailwind component which peaked at 27 knot at 5 feet RA, the lift generated by the wings decreased considerably and caused the aircraft to “drop”. This matches the pilots’ sensation of experiencing a “sudden drop”. ... The above factors contributed to the “drop” and the subsequent first touchdown onto the runway with the main landing gear resulted in a vertical acceleration of 2.36G, which was not considered as a hard landing (According to Airbus definition, a hard landing means a vertical acceleration that is equal to or more than 2.6G and less than 2.86G)."
The MCAA analysed the bounce, second touchdown and go around:
After the first touchdown with the main landing gear at a vertical acceleration of 2.36G, the aircraft bounced up at an initial pitch angle of about 7.5 degree nose up and lifted-off again, then reaching a maximum height of 7 feet RA.
According to flight data, at the first touchdown the thrust lever was not retarded to idle but moved to above the CLIMB detent (between MCT and TOGA detent). The Standard Operating Procedures mentioned that the pilot must ensure the thrust levers are at the idle detent to ensure ground spoiler extension at touchdown. The fact that the thrust levers position were above the CLIMB detent at the first touchdown was in contrary to the SOP. This prevented the activation of the Phased Lift Dumping (PLD) function. The PLD function is designed to reduce the severity of a possible bounce at landing by partially extending the ground spoiler under certain conditions, one of which being the thrust levers at or below the CLIMB detent (FCOM DSC-27-10-20).
Immediately after the first touchdown, an automatic callout “PITCH, PITCH” was triggered. This callout is designed to protect the aircraft from tail strike and is triggered when the aircraft has excessive nose up attitude.
According to flight data, after the bounce the PF applied a nose down side stick input. As a result, the pitch angle of the aircraft decreased from 7.5 degree nose up to 1.8 degree nose down in 4 seconds. During the bounce, the aircraft displaced 300 metres of runway.
One of the possibilities that the PF applied nose down input after the bounce was to respond to the “PITCH, PITCH” callout to avoid tail strike.
Moreover, flight data revealed that the thrust levers were moved to idle during the bounce, this resulted in the activation of the ground spoiler by the PLD function even when the aircraft was actually airborne (due to the memorization of the ground condition for 3 seconds).
Combining the extension of the ground spoilers and the aircraft attitude became nose down, the aircraft lost altitude and resulted in all three landing gears touched down within the same second. This second touchdown resulted in a vertical acceleration of 3.41G which was a severe hard landing (according to Airbus definition, any landing with a vertical acceleration equal to or more than 2.86G is a severe hard landing). At the second touchdown, the aircraft had a ground speed of about 156 knot (about 289 km/h) and airspeed of 146 knot. This second touchdown directly caused the fracture of the aircraft nose wheels.
According to the Airbus Flight Operations Briefing Notes – Landing Techniques – Bounce Recovery – Rejected Landing, in case of a bounced landing (regardless of a light bounce or high bounce), the typical recovery technique that should be applied is first to maintain a normal landing pitch attitude. This means the pilot should try to maintain the landing pitch angle. The same Briefing Notes also suggested that to recover from a light bounce, the pilot may choose to continue the landing and keep thrust at idle; or, in case of a high bounce, to initiate a go-around. In both cases and as mentioned before, a normal landing pitch attitude should be maintained.
Also, the SOP documented in the Beijing Capital Airline’s Flight Crew Training Manual recommended the maintenance of a pitch up attitude upon a light or high bounced landing (FCTM-PR-NP-SOP-250-00020014.0001001 / 20 MAR 17).
In this case, however, the PF executed nose down input at varying amplitude for about 7 seconds. This input was likely, initially, to response to the “PITCH, PITCH” callout to avoid excessive pitch angle (tail strike) but normal pitch attitude was compromised thereafter due to the continued and prolonged nose down input. This directly caused all three landing gears to touchdown within the same second, which led to the fracture of the aircraft nose wheels. At about 3 seconds after the second touchdown the PF initiated go-around by advancing the thrust levers to the TOGA position and engaged full nose up input.
Due to the full nose up input, the aircraft attitude increased to 15 degree nose up. This led to the second “PITCH, PITCH” callout and tail strike. The APU drain mast on the underside on the tailcone was damaged as a result.
The PF then applied nose down input to reduce the nose up attitude to around 7.7 degrees and the aircraft gradually climbed out of runway 34 of Macau International Airport.
Following the initiation of the go around engine #2 was able to operate up to 90% N1 despite having received damage from debris of the landing gear, the left hand engine reached about 50-60% N1 having received much more serious damage from the gear debris. The landing gear remained down, the crew commented they could not retract the landing gear. About 30 seconds after initiating the go around Macau tower advised the crew, he saw fire from the left hand engine, about the same time the crew received a right hand engine fire warning. The crew reduced the right hand engine to idle thrust and set the left engine to TOGA (which was able to produce only 55% N1).
The aircraft was unable to maintain altitude with that engine thrust, given also due to the fact that the gear was down. The aircraft settled in a descent of about 1500 fpm and reached a minimum of 622 feet AGL. The crew decided to apply thrust on the right hand engine again and move the thrust lever into the TOGA position. The crew queried left or right engine with ATC, however, ATC did not respond. The MCAA wrote: "The thrust lever of the Engine #2 was unnecessarily moved to the idle position
for about 15 seconds which led to the stall warning triggered twice. Around 35 seconds after the first request to the ATC to confirm which engine was on fire, a voice was heard on the cockpit voice record saying in English “Captain 5759, confirm which engine on fire”, the ATC immediately responded “left engine”. The left engine (Engine 1) thrust lever was then immediately moved to the idle position as shown by the flight data."
After landing no evidence of an engine fire was found, the MCAA analysed the fire observed probably were sparks caused by extensive engine rubbing.
The MCAA analysed that the nose gear failure was not caused by the wheel bearings, which did not show any distress of mechanical load or overload. The tyres however were found with overstress. The MCAA wrote: "The fracture surface of the 2 inboard wheel halves and 3 wheel center hubs collected were found with rough flat fracture and flat diagonal fracture, without any flat smooth fracture zone. The characteristic of the fracture surface shown the separation of the wheel halves were caused by overload fracture."
Metars Macau:
VMMC 280430Z 26017KT 9000 -SHRA FEW012 SCT025 27/25 Q1001 NOSIG=
VMMC 280400Z 23014KT 9999 FEW010 SCT025 28/26 Q1001 NOSIG=
COR VMMC 280330Z 22017KT 170V240 7000 -SHRA FEW009 FEW012CB SCT025 27/25 Q1002 TEMPO 20020G30KT 2500 TSRA=
VMMC 280300Z 20004KT 160V290 9999 FEW012 SCT030 29/26 Q1002 TEMPO VRB15G25KT 2500 TSRA FEW010CB SCT020=
VMMC 280230Z 18006KT 150V220 9999 FEW012 SCT030 29/26 Q1002 TEMPO 4000 SHRA FEW010CB SCT020=
VMMC 280200Z 19006KT 170V230 9999 FEW012 SCT030 29/26 Q1001 TEMPO 4000 SHRA=
VMMC 280130Z 18004KT 150V210 9999 FEW012 28/26 Q1001 NOSIG=
VMMC 280100Z VRB02KT 9000 FEW012 28/26 Q1001 NOSIG=
VMMC 280030Z VRB02KT 9000 FEW018 28/26 Q1001 NOSIG=
VMMC 280000Z VRB01KT 8000 FEW018 28/26 Q1001 NOSIG=
VMMC 272330Z VRB02KT 6000 FEW018 27/26 Q1001 NOSIG=
VMMC 272300Z 29001KT 6000 FEW018 26/25 Q1001 TEMPO 4000 BR=
VMMC 272230Z VRB01KT 6000 FEW018 25/25 Q1000 NOSIG=
VMMC 272200Z 28002KT 6000 FEW018 26/25 Q1000 TEMPO 4000 BR=
Metars Shenzhen:
ZGSZ 280500Z 17004MPS 9999 FEW020 FEW030CB 29/26 Q1001 BECMG AT0550 SHRA=
ZGSZ 280400Z 19003MPS 160V220 9999 FEW018 29/26 Q1002 BECMG AT0550 SHRA=
ZGSZ 280300Z 19003MPS 9999 FEW018 29/26 Q1002 NOSIG=
ZGSZ 280200Z 20002MPS 9999 FEW018 BKN030 29/26 Q1002 NOSIG=
ZGSZ 280100Z 11002MPS 070V140 9999 BKN036 28/25 Q1002 NOSIG=
ZGSZ 280000Z 11003MPS 8000 BKN036 27/25 Q1002 NOSIG=
ZGSZ 272300Z 09002MPS 070V130 7000 FEW011 26/25 Q1001 NOSIG=
ZGSZ 272200Z 11002MPS 7000 -RA FEW011 26/24 Q1001 NOSIG=
Incident Facts
Date of incident
Aug 28, 2018
Classification
Accident
Airline
Capital Airlines Beijing
Flight number
JD-5759
Departure
Beijing, Macau
Destination
Macau, Macau
Aircraft Registration
B-6952
Aircraft Type
Airbus A320
ICAO Type Designator
A320
This article is published under license from Avherald.com. © of text by Avherald.com.
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