parallel runways and ATC Collision warning

WannFly

WannFly

Final Approach
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the other night @Sinistar and me were talking about parallel runways and came up with a question...

i think your ATPC folks get some kind of warning when 2 aircraft are in collision course.. when say there are 2 aircrafts doing pattern in parallel runways and both are in base.... do you guys get the warning and hope both turn final where they are supposed to? how do you deal with a situation like that with the collision warning and just tune it out since you are talking to both ?
 
When vectoring to two, or more, parallel Finals, each runways Base leg is at a different altitude. If someone overshoots, they'll be vertically separated from traffic on the other runway(s).

With closely spaced parallel arrivals we (pilots) will often change TCAS to the TA-Only mode to prevent spurious resolution advisories.
 
Would also note that not all parallel runways are created equal. If the runways are less than 2500 feet apart (I might be smudging that number) a different set of separation rules apply.

If you're referencing VFR traffic on a base leg close to the airport, I'm not sure. I've never seen it come that close together. For the tower controller, who doesn't have a certified display, VFR traffic might not show a Collision Alert.
 
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Speaking anecdotally, a friend and I flew out to AFW to do our night landings for commercial, and they have parallels. When there was no one else in the pattern, tower would split us onto seperate runways. And whenever we lined up, tower would call out that there was traffic on opposite base. I don't know if she was getting any kind of warning though.
 
Lindberg said:
Speaking anecdotally, a friend and I flew out to AFW to do our night landings for commercial, and they have parallels. When there was no one else in the pattern, tower would split us onto seperate runways. And whenever we lined up, tower would call out that there was traffic on opposite base. I don't know if she was getting any kind of warning though.
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For those flying in the DFW area, KAFW (Alliance Airport north of Fort Worth) does a fun activity called a "Pattern Drill".

When requested, the tower controller has a list of things they will ask you to do that move you all over the place while in the landing pattern. This mimics what they might need to ask of you when things are tilting toward the crazy busy side. Side step to different runway, go around with additional instructions like mid field cross to other downwind, light signal gun, and more. Takes about 30-40 minutes to do.

It is a fun activity to exercise your staying ahead of the airplane skills and keeping sharp on what to do when while in the pattern.
 
Larry in TN said:
When vectoring to two, or more, parallel Finals, each runways Base leg is at a different altitude. If someone overshoots, they'll be vertically separated from traffic on the other runway(s).

With closely spaced parallel arrivals we (pilots) will often change TCAS to the TA-Only mode to prevent spurious resolution advisories.
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I have never heard or been given different altitudes for base legs at the airport @WannFly is indirectly referring to. At KFCM they just call right or left patterns. You will be given a ATC call out that there is traffic arriving on the opposite parallel and also on base (forget the exact verbiage). I am pretty sure these parallels are less than 2500 apart. I think @WannFly's question stemmed from the fact I was telling him that the GTX345 is pretty chatty (traffic callouts) at this airport and this specific case (direct head on base legs) the 345 callouts were quite good actually.

But I have never heard audible alarms going off in the background like you do when on with App/Dep and two planes are getting close such as around KMSP. So that must mean at airports with tight parallels the tower doesn't have an audible alarm or it would just be too much noise and its off.
 
Larry in TN said:
That is interesting. Do you know the genesis of them offering that service?
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No to the exact details. It was available since at least 2009 when I was a student pilot. My primary instructor introduced me to it as a means of sharpening up some of my pattern skills that were a tad sloppy at the time.
 
Years ago going into PHX we were on a long final for Rwy 7L or R in our Citation. South West was on a left base for Rwy 8 but I think the pilot was headed for Rwy 7L, they overshot Rwy 8 and was headed pretty close to us. Tower got very excited, SW was on a different tower freq so I could not hear them. I told tower I had them in sight and could maintain visual separation. I just stopped my decent and slowed as SW corrected and pulled away. Ground gave me a phone number to call. When I called they just wanted my side of the story and to know if I was concerned about what had happened. I said I was not concerned but SW did get a little close. I never heard anything back but I bet the SW crew had some dancing to do. I cannot remember if I heard any alarms going off in the tower's transmissions but I bet they had some.
 
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Sinistar said:
I have never heard or been given different altitudes for base legs at the airport @WannFly is indirectly referring to.
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I specified vectors to final, not VFR traffic patterns. With VFR traffic patterns ATC isn't providing separation in the air, only runway separation. When ATC has to provide the separation, they do as I described. The busier airports will often do it with VFR arrivals, too.
 
Patterns and parallel runways.

Years ago, I refueled at Dayton, Ohio, arriving with a true airspeed of 140, and a 40 K tailwind, in a Franklin powered C172.

The handoffs from cruise were smooth, but the expect clearance to land on 27 Right was a surprise.

The altitude assigned was 500 feet above the normal Cessna and equivalent one, and then as I went by the tower, they called and asked my tail number and location. Yep, they thought that I was a much larger Cessna.
Next call was "Descend 500 feet, your traffic is a red Cessna 150, expect clearance to land 27 Left".

So the separation there was by altitude, but both classes of aircraft on the same side, downwind a bit longer for the longer runway, so no conflicts.

From 140 K to follow a Cessna 150 just 1/4 mile ahead is a challenge. Throttle to idle, prop to max for drag, maintain altitude until into white arc, 40 degrees of flaps, and at 55 K, start losing altitude, still nearly over him.

Fondly remembered, the best tailwind I ever had, at 11,000 feet, 60 K at 270, and the big Franklin was giving me 140 true air speed.
 
Don’t know if ATL tower has “CA CA” inhibited but TRACON has to have it on. Not only is it going off all the time, it triggers a alert or “snitch patch” that QA has to investigate. They get hundreds of these a day. If visual is being used between aircraft, the controller will put a “V” in the scratch pad so no one is throwing a fit when prescribed sep is lost.

It’s not just parallels either. CAs and MSAWS go off all the time in radar for different reasons. They both use a set of algorithms that trigger the alert way before any IFR sep / terrain is lost. Some days I’d go home with a headache from listening to that crap all day.
 
Larry in TN said:
That is interesting. Do you know the genesis of them offering that service?
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The airport has been historically very sleepy, but it was built to be a Big Important Airport so they always wanted traffic. Shortly after it was built, there was nothing there but Flight Safety, AA's maintenence, and a really nice FBO. The tower had nothing to do 99% of the time.

I visited the tower sometime in '93 on the outbound leg of a xcty. The controller basically begged us to stay, and asked us to stop on our way back. Back then there wasn't really much traffic even transiting their airspace.

So the pattern drill goes back to the beginning. Back before the internet, it was described in the little airport handbook that a lot of towers used to distribute. They had a radar feed too, and I remember the booklet saying that you could fly triangles to let them know you wanted to practice nordo operations.
 
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Velocity173 said:
Don’t know if ATL tower has “CA CA” inhibited but TRACON has to have it on. Not only is it going off all the time, it triggers a alert or “snitch patch” that QA has to investigate. They get hundreds of these a day. If visual is being used between aircraft, the controller will put a “V” in the scratch pad so no one is throwing a fit when prescribed sep is lost.

It’s not just parallels either. CAs and MSAWS go off all the time in radar for different reasons. They both use a set of algorithms that trigger the alert way before any IFR sep / terrain is lost. Some days I’d go home with a headache from listening to that crap all day.
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At ATL the majority of alerts they are going to get are going to come from the ASDE-X and those aren't just alarms, you get an audible "Alert, runway xyz occupied" or some other audible warning along with an alert on the display.
 
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