Date: 202105
Local time of day: 1801-2400
Location: SAN.Airport, CA
Flight conditions: IMC
Light: Night
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B SAN
ATC / advisory: Tower SAN
Second aircraft: Commercial Fixed Wing
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: First Officer; Pilot Not Flying
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach; Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Arriving in San Diego; we had been cleared for the RNAV Z Runway 27 approach. We checked in with the Tower and were cleared to land. I heard Tower instruct a [heavy jet] to; 'Line up and wait; traffic on an 8 mile final'. Checklists and callouts may have masked additional communications on the frequency because I can't recall whether the [heavy jet] flight was cleared for takeoff; or not. We broke out of IMC at approximately 1400 feet. The Pilot Monitoring called 'Runway in Sight - Landing'. Shortly thereafter; the First Officer said; 'Is that an airplane on the runway? I looked closer and honestly could not tell. The navigation and beacon lights were blending into the approach lights and it was difficult to distinguish the aircraft. We had to get closer before the actual structure of the airplane was apparent. We had already determined that a go-around/missed approach was necessary; but before we could communicate that to the Tower Controller; she issued the go-around instruction; 'Fly the published Missed Approach; and contact Departure'. I had observed that the offending aircraft was stationary on the runway; and not in the midst of a takeoff roll; so I knew that the published missed approach or runway heading was appropriate; and that a sidestep departure for spacing was not necessary. So we complied as instructed. We had already determined our BINGO fuel enroute and knew that we could accept one more approach before diverting to our alternate; so we accepted vectors back for another approach. The subsequent approach and landing was uneventful. The [heavy jet] had been removed from the runway and was still holding short when we landed. No mention of the reason for the go-around was given by the Tower; nor did we ask. Because we knew. There was an airplane on the runway.     Cause: [The] decision to work a Maintenance Irregularity while on an active runway. The Tower's decision to put the [heavy jet] on the runway when they were not ready to depart; and then forgetting about them. And our loss of situational awareness based on the radio communications that were; or were not; taking place on the Tower Frequency.In the future; if the First Officer questions the security of the runway; or the landing clearance; I will instruct them to simply; and without delay; to ask the Tower. This would NOT have prevented the necessity to go-around; but perhaps would have initiated the maneuver a little sooner."


Second narrative: While on the RNAV Z 27; we were handed off to Tower and were cleared to land. This occurred at approximately SAYAE intersection. The approach continued normally and we broke out about 1;400 feet and then called 'runway in sight'; 'runway in sight landing'. Sometime after the 1;000 feet stabilized cleared to land call; I noticed what appeared to be an airplane on the displaced threshold of Runway 27 and said; 'Is that an airplane on the runway? The darkness of the displaced threshold area against the runway lights and the fact that the aircraft was in position pointed away from us made it difficult to tell. However; by the times the words were spoken; we were close enough to see. At the very same moment we began our go-around; the Tower issued instructions to go around and fly the published missed approach; which we did since the aircraft on the runway did not appear to be moving. We proceeded with a normal go-around and returned for a normal landing since we had sufficient fuel. In the simplest terms; we executed a normal go around due to an aircraft on the runway. Why was there an aircraft on the runway? I am not sure. Shortly after we were cleared to land; we heard the tower instruct [another aircraft] to line up and wait; traffic 8 mile final. I honestly don't recall hearing a take-off clearance; perhaps due our being engaged with our tasks and callouts during the approach. We did see the aircraft short of the runway when we returned. It wasn't until later that we read that they had a mechanical issue.Maintaining better awareness of traffic utilizing the runway particularly when we can't see it yet. Better awareness would have allowed us to question if the runway was indeed clear. That may not have prevented the go around this time; it would've depended on how soon we became aware."


Synopsis: Air carrier flight crew reported executing a go-around at SAN when it became clear another air carrier aircraft was in position for takeoff on their landing runway.