Flight History
On 2 September 2019, at about 0133 local time, a Boeing B777-300ER took off from Pudong Airport in Shanghai, China, on a scheduled flight to Singapore. The aircraft was registered as 9V-SWD and operated by Singapore Airlines. The flight crew consisted of a Pilot-in-Command (PIC) and a First Officer (FO). There were 120 persons on board.
Pre-departure Events
Prior to departure, the flight crew encountered several issues. Bad weather caused delays to many flights and required the aircraft to park at a remote bay, leading to transport difficulties. The PIC intervened to secure transport to the aircraft. Upon arrival, both pilots reviewed the aircraft's electronic logbook and noted five deferred defects under the Minimum Equipment List (MEL). The most significant was MEL item 36-22-01-05A, concerning an inoperative pneumatic manifold temperature sensor on the right engine bleed system. The PIC familiarized himself with the associated procedures and discussed them with the FO after the FO's exterior walk-around check.
The FO experienced intermittent connectivity with the Controller-Pilot Data Link Communications (CPDLC) when requesting the Pre-Departure Clearance (PDC). Meanwhile, the PIC had difficulties obtaining the zero-fuel weight and flight route via the Aircraft Communication Addressing and Reporting System (ACARS). He manually entered the flight route and Standard Instrument Departure (SID) HSN 22X into the Flight Management Computer (FMC) as RTE 1. Later, after the FO successfully obtained the PDC, the assigned runway changed from 34L to 35R and the SID from HSN 22X to HSN 12X. The PIC used the ROUTE COPY function to duplicate RTE 1 into RTE 2 and amended the SID accordingly. He noted that the first waypoint of the new SID, PD062, had no speed/altitude crossing constraint, unlike the previous SID's waypoint HSH which had a constraint of '250/1970A'.
Incident Sequence
After takeoff, the flight crew engaged the autopilot with Vertical Navigation (VNAV) pitch mode. Shortly thereafter, the Enhanced Ground Proximity Warning System (EGPWS) activated the 'DON'T SINK' caution alert three times. The crew performed troubleshooting by selecting the Flight Level Change (FLCH) mode on the Mode Control Panel to climb the aircraft. Once the caution alert ceased, they reverted to VNAV mode. Subsequently, another 'DON'T SINK' caution alert was activated, followed by a 'PULL UP' warning alert. In response, the crew disengaged the autopilot, increased engine thrust, and pitched the aircraft to climb. The warning alert stopped, and the flight proceeded without further incident.
Investigation
The Transport Safety Investigation Bureau (TSIB) of Singapore classified the occurrence as an incident. The investigation focused on the flight history and pre-departure events, but no probable cause was explicitly stated in the initial factual information.