Date: 202104
Local time of day: 0001-0600
Location: VHHH.Tower, FO
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Initial Approach
ATC / advisory: Tower VHHH
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Time Pressure; Distraction
Anomaly: Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Air Traffic Control; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Took Evasive Action; Flight Crew Executed Go Around / Missed Approach
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: ATC cleared direct LOTUS then ILS [Runway] 25L approach into HKG. Observed aircraft tracking direct LOTUS on LNAV; above path and on course to cross LOTUS above 4;500 ft. (which is the published altitude for LOTUS; the LOC course intercept). Vertical mode was FLCH to recapture the path; which was below us due to the ATC instruction to proceed direct LOTUS early in the approach. Captain armed the approach just outside of LOTUS. Called LOC capture over LOTUS; observed aircraft still above glideslope and stated 'glideslope alive'. Reported established; ILS Runway 25L to ATC; and HKG Approach instructed us to continue. Aircraft was descending steadily toward the glideslope at the required 180 kts. and I turned to my EFB (Electronic Flight Bag) for a moment to look up the next speed restriction. At this time ATC issued a low altitude alert and commanded a go-around; and the Captain followed up with a 'go-around; flaps 20' command and initiated the go-around. I selected flaps 20 and spun the altitude selector up to 5;000 ft.; as it was still set at the FAF altitude of 1;300 ft.; and notified ATC of the go-around. I initally looked at my MFD which was in TERR mode and saw no alerts or terrain indicated ahead; only yellow high ground 2-3nm right of course. I looked at the GS indicator and saw we were 1 dot below slope. I am unsure if the GS had captured; as by the time I looked at the FMA; the mode was already in TO/GA. Terrain was no longer the focus at this time as the aircraft climbed very rapidly and we reconfigured the aircraft and autoflight systems for the missed approach. We were initially instructed to fly the published missed except to maintain 6;000 [ft.]; then accepted vectors for another ILS approach to RWY 25L which was conducted without further incident. Following landing we copied a telephone number to call; which the Captain contacted after shutdown. The Tower Supervisor informed him that we were 200 ft. low at LOTUS; which is what prompted the low altitude alert. At time of writing I am unsure whether or not we were actually 200 ft. low at LOTUS. Immediately after the event I was sure we were above path and still descending toward the glideslope. Conversely; I know we were below GS when the GA (Go-Around) commenced; and cannot discount the controller's observations; nor the fact that FLCH does not protect against FMC altitude constraints. I had been monitoring the GS leading up to the event in order to call 'Glideslope captured' whenever it occurred; but as stated I looked away at the moment in question to look up the next speed constraint in the notes section of the approach plate (a speed constraint that; as I noted; we were still a few miles away from). With this in mind it's apparent that our vertical path was the more paramount of my PM (Pilot Monitoring) tasks and that I could have waited until the glideslope captured to look away. Especially in FLCH in a high-terrain environment; extra vigilance was warranted.




Synopsis: Air Carrier First Officer reported receiving a Low Altitude Alert from the tower controller.