Thanks! I feel a little sheepish not realizing the obvious...
One other question that might have an obvious answer: how did the pilots become aware of the other plane?
It would be interesting if it was due to radio comms. It implies that this was a shining example of multiple failsafes -- the other plane was coming in for a landing, had already reported that they were landing, but reported it again, and this pilot heard it went "Oh shit."
It would be equally fascinating if the pilot saw the other plane out the window. It implies that if this had happened at night, everyone could have died.
I think it would actually be easier to spot a plane at night due to the lights on the plane. I'm not sure how easy it is to determine how far away the plane is though.
(Private) pilot here - relevant for this question only because I hung around airports and runways long enough, not for my piloting.
You can see the light easily even during the day when they are flying towards you. It's like cars using their high beam lights - and looking at them on the same straight road from the opposite direction. You are directly in the main cone of where that light is focused.
These days even bikes with their LED headlights on during the day can be quite annoying to people having to look straight at them on the same path even when they still are a hundred meters away. That light on the airplane, the landing light, is meant to illuminate the runway when landing - small airplanes may have to do a night landing on barely illuminated runways. I did some of those, you could only see the outline of the runway and everything else was a blackhole, the surroundings and the runway itself. The runway itself only became visible when I got within a few meters above it. I'm just saying this to show that those lights are not just decoration or position indicator but actually quite strong.
It would be hard to miss that light in the sky (unless you take off towards the sun of course) when it's flying towards where you are and you look straight at it. Fortunately I only ever saw it from such a position waiting next to the runway, not standing right on it (now that would be a panic attack moment). Also, usually takeoff and landing use the same direction, into the wind, in both cases to reduce the amount of runway needed (speed in relation to ground is less than speed in relation to air in that case).
From what I gather, TCAS is tricky at an airport environment as there are "close calls" somewhat routinely. Resolution advisories are definitely inhibited. Some more info here:
Or just to get off the ground so you can get out of the way, can’t really turn until you’re airborne