Parallel Runway Collision Alerts

[SimmerCanuck]

Just discovered Tower!3D Pro this week and have already spent lots of time that I didn't have and controlled airplanes in my sleep. I'm fairly comfortable controlling KPHL at 100% traffic with a westerly flow, arrivals on 27L, departures on 27R. I have encountered one specific problem 3 or 4 times so far. I suspect that this is planned behaviour and I just need to learn to avoid the situation - but thought I'd ask here.

If I have a departure on 27R take off at the same time an arrival on 27L is landing, I get an Air Collision Alert (and -500 pts) between the 2 airplanes. Here's what the logs show.

10:35:11 alt: 0 takeoff: True/False/-1 OWNER_GROUND r: 27R * DAL1478 => STATE CHANGE from STATE_TAKEOFFUP to STATE_FLYAWAY
10:35:16 * DAL1478 => ADD HISTORY: Air Collision Alert! ( DAL1478 - PDT4821 ) -500 pts
10:35:17 alt: 99 takeoff: False/False/-2 OWNER_TOWER r: 27L * PDT4821 => STATE CHANGE from STATE_INCOMING to STATE_LAND

With the runways being about 1400' apart and the threshold for 27L about 4500' past the 27R threshold, I can see that these 2 airplanes are in fact airborne and probably only have <2500' horizontal separation. They are however travelling in the same direction and there are no options for diverging headings.

I think I've answered my own question, but if someone could confirm that I just need to avoid starting takeoff rolls while parallel traffic is on short final that would help. Of course I could switch runways, but that gets really messy trying to get your outbound taxis across the runway with the landing traffic. I think that in the real world, 27R is used for landings while 27L is used for takeoffs during segregated operations - maybe that's for the same reasons as I'm getting this error.

Thanks. This is a great sim, my biggest complaint about it is that my headset is not comfortable enough to make it though a good 3 hour session. 😎

 

[crbascott]

As you said, you answered your own question. This scenario is definitely one of the reasons why KPHL uses 27L for departures and 27R for arrivals when in west flow.

[Daemien67]

Yeah, gotta watch that runway separation!