On 21 March 2022, in normal day visibility, an Airbus A320 (B-2337) being operated by China Eastern Airlines on a scheduled domestic passenger flight from Shanghai Hongqiao to Tianjin as MU5643 with an observer occupying the flight deck supernumerary crew seat was already at high speed for takeoff when an Airbus A330-300 (B6506) also being operated by China Eastern Airlines on a scheduled domestic passenger flight from Beijing to Shanghai Honqiao as MU5106 and which had recently landed on adjacent parallel runway 36R was seen to emerge from a taxiway and begin to cross the runway ahead. As it continued to do so, the A320 crew avoided a collision by initiating an early rotation and just cleared the vertical stabiliser of the A330. A total of 437 passengers and crew were on board the two aircraft.
The Civil Aviation Administration of China (CAAC) determined that the conflict had been an ICAO Category ‘A’ Runway Incursion and a Serious Incident Investigation was carried out by the Aviation Safety Office of the Administration. Relevant FDR data and CVR data from the A320 were successfully downloaded but relevant CVR data from the A330 was overwritten after it was not secured.
In excellent visibility, an inbound A330 had cleared landing runway 36R with a left turn onto taxiway H4 and was transferred to the 36L runway control frequency where it was cleared to cross central taxiway ‘B’ and continue to the runway 36L holding point. Seven seconds after this instruction and before reaching the holding point, the flight was re-cleared to continue on H4 across the runway to the apron. There was no precautionary crew check that the runway was clear before beginning to cross but as the aircraft emerged further onto the runway six seconds after crossing the holding point, its crew realised that the A320 they had earlier observed stationary at the beginning of runway 36L was actually taking off. FDR data from the A330 recorded a rapid increase in thrust and a consequent increase in ground speed to 25 knots in 4 seconds by the time it was 10 metres into the crossing in order to complete it more quickly. Concurrently with this response, the runway controller made two calls to stop which were not responded to.
The departing A320 with the First Officer as PF had been initially instructed to line up and wait for a full length takeoff from the 3,300 metre-long 60 metre-wide runway 36L (see the aerodrome diagram extract below) and entered the runway from taxiway H7. After subsequent receipt of takeoff clearance, it was commenced with V1 set to 146 KIAS.
The A320 crew only detected the A330 beginning to cross when accelerating through 110 KCAS and approximately 1600 metres into their takeoff roll. As the acceleration continued and V1 got closer, the PF First Officer initially responded by pulling the side stick to achieve a recorded 5.54° nose up and applied brakes. The aircraft pitched up and the NLG left the ground for one second but the side stick pressure was then released and the NLG contacted the ground again. The Captain took control and pulled the side stick to the mechanical stop for maximum nose up pitch and simultaneously moved the thrust levers forwards from the FLEX/MCT detent into the TOGA detent. Within two seconds, the aircraft rotated to a recorded 8.44°. As the First Officer also pulled back on his sidestick, a dual input alert was triggered. The aircraft became fully airborne with about 250 metres to go to the intersection. By the time the A320 flew over the A330, it had still not fully cleared the runway and the vertical separation from the A330 vertical stabiliser was subsequently computed as 19 metres and the wingtip to wingtip horizontal separation as 13 metres.
An extract from the Shanghai Hongqiao Aerodrome Diagram. [Reproduced from the AIP]
Why It Happened
Examination of the recorded ATC data found that the A330 had been cleared to cross runway 36L at H4 by the same controller who subsequently gave a takeoff clearance to the A320, having forgotten about the earlier crossing clearance. The A320 crew did not notice that this clearance could conflict with their takeoff clearance.
The fact that the A330 crew decided to speed up rather than stop when already partly on the runway despite the controller’s repeated instruction to stop was considered appropriate but their failure to routinely make a precautionary visual check before beginning to enter an active runway even with a clearance to do so meant they had “blindly trusted the ATC instructions given and was poor airmanship”.
The A320 Captain’s takeover of control and decision to initiate a maximum rate climb rather than attempt a rejected takeoff was considered appropriate given the 4 seconds in which “the First Officer's actions showed he was hesitant to make a decision seeing the other aircraft in front of them”.
The circumstances which led the controller involved to issue conflicting clearances were examined. It was found that the controller assigned to the TWR position when the A320 was instructed to hold short of runway 36L had then decided he needed to take a toilet break. The Assistant Controller nearby who was fully qualified as a TWR controller therefore took over. However, he remained in his Assistant’s seat and was observed to operate without donning a headset. He issued the A330 with a crossing clearance and instructed the A320 to line up and wait. Although he had access to the electronic clearance recording system and access to ground surveillance radar and the VHF control panel, the Assistant Controller was found to “have had difficulty grasping the real time traffic dynamics”. In addition, no hand over procedure between the two controllers was conducted and it was also noted that the height of the Assistant Controller’s seat was lower than the Tower Controller's seat which resulted in incomplete external visual observation with the pillars between the windows of the Visual Control Room obstructing the view onto the south end of runway 36L.
When the A320 began takeoff, the Assistant Controller who had just issued its takeoff clearance was found to have been “querying with other controllers present whether they had their radio volumes turned fully up”. Distracted by his own weak radio problem, he had briefly left his seat to have the suspect equipment radio replaced. When the observer on the A320 flight deck subsequently queried the presence of another aircraft entering the runway ahead, the controller was observed to have “changed his posture and began to keep an eye on the dynamics near H4” and had issued and repeated a “hold position” instruction to the A330 twice without “paying the necessary attention to the situation" and “did not recognise the conflict between the two aircraft”. Shortly afterwards, the assigned TWR Controller returned to his seat but initially remained unaware of the runway incursion.
The TWR shift supervisor was also found not to have followed relevant regulations and had not used effective and continuous visual observation as well as use their monitoring equipment to ensure they remained aware of the relative dynamics of the control environment. As a result it was considered that his loss of situational awareness and inability to detect and correct controllers' mistakes had mitigated against effective prevention of runway incursions resulting from controller error.
The Probable Cause of the Serious Incident was formally documented as “the controller in position at the Hongqiao West Tower issued a takeoff clearance to the A320 aircraft in violation of the Basic Flight Regulations of the People's Republic of China and the East China Air Traffic Control's Operations Manual in particular by not maintaining continuous and effective visual surveillance. He had already issued a runway crossing clearance to the A330”.
Editor’s Note: Whilst the Final Report of the Investigation by the CAAC Aviation Safety Office was not published, extracts were made available and have formed the basis for this unofficial summary.