# Course of other planes approaching the airport

I flew from MUC to TXL recently and made a weird observation. I was sitting in the port side of the plane and -just a few minutes before landing- saw a red light at approximately our height just before our wing tip. "Ok, I thought, that's odd. That other plane appears to be flying in the opposite direction but it cannot have just started, so maybe a holding pattern or something". While I was pondering that our plane switched on the landing (?) lights. And to my irritation that other plane did as well. "If they are about to land, should they not be behind or in front of us?", I thought.

But what irritated me the most was that the relative position (i.e., the bearing) of that other plane did not change at all. I've learned in boat school that another object with a constant relative bearing is probably on a collision course. It could also be on a parallel course with the same speed, but we were descending towards the airport - TXL does not have parallel landing strips AFAIK. I have no idea how far away that other plane was.

So here are my questions:

1. Is my assessment of the situation correct or do I miss something?
2. Is there a point during a landing approach were planes can be on a collision course (because one or both are to make course changes), I always thought that planes would be arranged in some long line twoards the airport, much like a highway.
3. When is it a good idea to mention such an observation to the crew? How would one do it without looking like a busybody?

edit: Thanks to the great comment about flightradar (I did not know about the playback), I could sort out what probably happened.

1. There was indeed a flight on a collision course. A plane from STR on its way to TXL came from the south. We came (roughly) from south-southeast. Our flight paths would have crossed somewhere north of TXL. We turned right into the queue first, the other plane did the same, but slightly behind.

2. A third plane heading southwest crossed roughly (from my perspective) the line between the two planes.

So I must have seen the third plane first and then the second plane. We were indeed on a collision course, but with a rather large distance and with both planes scheduled for right turns.

• You can go to flightradar24 and see exactly what aircraft you saw and its relationship to your plane – TomMcW Nov 22 '18 at 16:50
• It almost sounds like you're describing a reflection of the aircraft you were in, but I don't know what conditions would allow that. Did you actually see the other aircraft, or just its lights? And were you in clouds? – Pondlife Nov 22 '18 at 19:27