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IslandRob
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WN-DL Close Call At MDW

Wed Jun 17, 2015 11:51 pm

Link to article: http://abcnews.go.com/US/wireStory/f...l-chicagos-midway-airport-31839614

Quotes:

"Two passenger jets began to take off at the same time on intersecting runways at Chicago's Midway International Airport, prompting a controller to shout over the radio for one of the pilots to halt to avoid a collision, aviation officials said Wednesday."

"1328, stop, stop stop!" the controller shouted, according to audio posted on the website LiveATC.net.

[Edited 2015-06-17 16:52:56]

[Edited 2015-06-17 16:56:50]

[Edited 2015-06-17 17:05:31]
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KarlB737
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RE: WN-DL Close Call At MDW (June 17)

Wed Jun 17, 2015 11:58 pm

Local Chicago station WLS-TV has this video report:

Midway Airport Runway Close Call Under Investigation

http://abc7chicago.com/news/midway-a...e-call-under-investigation/790765/
 
wjcandee
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RE: WN-DL Close Call At MDW (June 17)

Thu Jun 18, 2015 12:03 am

That's an amazing recording. 1328 and 3828 get themselves all confused and keep acknowledging over each other at the same time, until the controller figures out the problem.

However, Delta is majorly in trouble, because they mistook Southwest's takeoff clearance for their own. What is particularly pernicious is that the clearance was specific as to the runway they were being cleared to take off on. They heard "28" and started rolling, even though they were on 4R, not 31Center, and the clearance was expressly for the aircraft on 31Center, and the tower repeated in the clear that Southwest 3828 was the one being cleared for takeoff on 13Center. DL1328 was told to line up and wait on 4R, with traffic on an intersecting runway holding in position. The DL guys just weren't listening, totally had lost situational awareness, and it could have been a major accident squarely on their shoulders.

A real call needs to be made for an end to the simplex voice communications in favor of the duplex system used by pretty much anyone with a decent radio these days. Ends the stepping on each other.

The DL flight is not a contract carrier; it's a company 717.

One thing I never hear on the tape is the tower telling the aircraft that was cleared to land on the runway to go around. So I guess DL got off the runway fast enough after the abort. The FO is working radios as they line up and wait, and after they abort, it's clearly the CPT communicating. Experienced captain as PF, and still a FU like this...

Live ATC link to the excerpt. http://www.liveatc.net/forums/index....dlattach;topic=12488.0;attach=8376

[Edited 2015-06-17 17:04:30]

[Edited 2015-06-17 17:14:04]
 
Okie
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 12:06 am

Quoting IslandRob (Thread starter):
"1328, stop, stop stop!" the controller shouted, according to audio posted on the website LiveATC.net.[Edited 2015-06-17 16:52:56]

Flight Thirteen Twenty Eight and Flight Thirty Two Twenty Eight.

Some one just heard the Twenty Eight part.


Okie
 
wjcandee
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 12:17 am

Quoting Okie (Reply 3):
Flight Thirty Two Twenty Eight.

It's Thirty EIGHT Twenty Eight, which is actually more confusing.

Actually, the entire callsigns sound similar. There are similar mouth sounds on "thirty eight" and "thirteen"

The DELTA and SOUTHWEST, however, don't. Nor does RUNWAY FOUR RIGHT sound like RUNWAY THIRTY-ONE CENTER.

(The caps aren't yelling, just emphasizing the important words. And I agree with the essence of your post.)
 
bcoz
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 12:18 am

What's strange to me is the fact that they were using two different runways for takeoffs. I've been flying in and out of MDW for more than ten years and I don't think I've seen that before. Arrivals on one runway and departures on another, yes.... but not simultaneous departures on intersecting runways. Someone can correct me if I am wrong and this is standard ops.

bcoz
 
wjcandee
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 12:22 am

I have seen the occasional flight being sent off on the intersecting runway. They weren't necessarily lining up a bunch of planes to take off on each runway. 4R was apparently the landing runway at the time.
 
SPREE34
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 12:30 am

Quoting wjcandee (Reply 2):
A real call needs to be made for an end to the simplex voice communications in favor of the duplex system used by pretty much anyone with a decent radio these days. Ends the stepping on each other.

How so? Even in duplex, if two speak at once, the listening station can get garble.
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WROORD
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 12:33 am

I am glad they were able to correct the situation and most importantly stop. Those runways are not that long...
 
MaverickTTT
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 12:43 am

Quoting bcoz (Reply 5):
What's strange to me is the fact that they were using two different runways for takeoffs. I've been flying in and out of MDW for more than ten years and I don't think I've seen that before.

When MDW is in a landing/departing 04R configuration, 31C is typically made available for departures by pilot request due to the fact that takeoff performance tends to be better on 31C (longer runway, the lack of skyscrapers on the extended centerline, etc.). Thus, it is not completely abnormal to have back-to-back departures off of 04R and 31C, especially in the summer months when takeoff performance is further impacted by warm temperatures.
 
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 12:46 am

Quoting wjcandee (Reply 2):
One thing I never hear on the tape is the tower telling the aircraft that was cleared to land on the runway to go around. So I guess DL got off the runway fast enough after the abort. The FO is working radios as they line up and wait, and after they abort, it's clearly the CPT communicating. Experienced captain as PF, and still a FU like this...

Avherald says that 4L was being used for landings, not 4R. It's at 0:10 of the LiveATC recording you linked.
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N415XJ
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 1:34 am

According to the ABC report, the pilot "answered in a clam voice". Perhaps that was the problem- shellfish can be particularly difficult to understand over the radio   Anyway, it's a good thing nothing happened. Imagine if someone else had called in right before the controller yelled stop, blocking him? Communication issues are a problem, and it's only a matter of time before something happens. Just wondering- would it be possible to have some sort of annunciator light that goes off in the cockpit, triggered by ATC when the aircraft is cleared to takeoff? Such an annunciator could prevent the potential tragedies that this and the 1999 O'Hare Korean/Air China incidents almost become.
 
N353SK
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 2:16 am

Quoting N415XJ (Reply 11):
Just wondering- would it be possible to have some sort of annunciator light that goes off in the cockpit, triggered by ATC when the aircraft is cleared to takeoff?

The FAA is working on implementing Runway Status Lights that are supposed to automatically alert you when the runway is unsafe: http://www.skybrary.aero/index.php/Runway_Status_Lights_(RWSL)
 
OMP777X
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 3:29 am

What I just heard while listening to the radio transmissions is that the ground controller informed the WN crew ahead of time that there was another flight also about to take off with a similar call sign to theirs. That probably helped them abort much quicker when they heard the call to stop. Giving them that heads up may have helped save them all. Had they not been warned at all, and had both crews lost their situational awareness, one or both may have actually ended up continuing their take off roll. At the end of the day, thankfully we aren't all talking about a collision with many deaths involved.

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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 3:31 am

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nikeherc
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 3:38 am

Quoting N353SK (Reply 12):
The FAA is working on implementing Runway Status Lights that are supposed to automatically alert you when the runway is unsafe: http://www.skybrary.aero/index.php/Runway_Status_Lights_(RWSL)

In the old, old days many aircraft didn't have radios and the tower would hold and clear planes with red and green spotlights aimed at the cockpits.
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maxpower1954
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 3:40 am

Quoting N353SK (Reply 12):
The FAA is working on implementing Runway Status Lights that are supposed to automatically alert you when the runway is unsafe: http://www.skybrary.aero/index.php/Runway_Status_Lights_(RWSL)

Installed and operational at CLT for almost a year now. I like the redundancy the system provides.
 
trnswrld
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 4:00 am

What are the rules with U.S. carriers as far as radio communications? Do they typically designate one pilot to do the communications and the other pilot can sort of ease off paying attention to the radio or is it absolutely both pilots responsibility to hear and confirm the clearance?
So for example, in this Delta cockpit was one pilot at fault here where one is in charge of the radios and the other pilot may have been doing some other task while waiting for clearance? In other words, regardless of which pilot incorrectly read the takeoff clearance, would both delta pilots be at fault here?
It's too bad this happened, but call sign issues happen ALL the time, just not to this extent in the terminal environment.
 
IADCA
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 4:48 am

Quoting OMP777X (Reply 13):
What I just heard while listening to the radio transmissions is that the ground controller informed the WN crew ahead of time that there was another flight also about to take off with a similar call sign to theirs. That probably helped them abort much quicker when they heard the call to stop.

There's a recording on liveatc with the full thing, and the warning was both directions. Both cockpits acknowledged the tower after being told there was a similar call sign on the frequency. The call sign mix up is the major contributing factor here, but it seems pretty clear the proximate cause is the DL pilots rolling without clearance. (And afterwards, the WN pilots even checked with the tower to make sure they were in the right, presumably to assist them in determining what to tell their employers.)

For those who have any interest in it, DL1328 was a 717 operating MDW-ATL; WN 3828 looks like A 73G on DEN-MDW-TUL-HOU.
 
FighterPilot
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 4:55 am

As a corrective action will either carrier change their flight number to avoid this in the future, if so, who?

Cal   
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wjcandee
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 5:08 am

Quoting SPREE34 (Reply 7):
How so? Even in duplex, if two speak at once, the listening station can get garble.

The aircraft can always hear the tower. Here, parts of what the tower was saying were also squelched; at one point, all you hear is "28" from the tower when talking. And some of the readback blocked some of the tower. It wasn't the primary problem, but had the tower been fully-audible all the time, there is a higher potential that the mistake would have been caught by the pilots.
 
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 5:18 am

Quoting cjg225 (Reply 10):
Avherald says that 4L was being used for landings, not 4R. It's at 0:10 of the LiveATC recording you linked.

AvHerald is wrong. After determining ExecJet's parking, they "change to and clear to" land ExecJet on 4L. He comes in on ILS for 4R. After ExecJet, as you listen to the whole tape, there are multiple aircraft, in trail, being cleared to land on 4R, not so on 4L, throughout the entire sequence.
 
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 5:27 am

Quoting IADCA (Reply 18):
Both cockpits acknowledged the tower after being told there was a similar call sign on the frequency. The call sign mix up is the major contributing factor here, but it seems pretty clear the proximate cause is the DL pilots rolling without clearance.

Correct, LiveATC has one recording of Clearance-Delivery from pre-push to contacting tower, and another recording of Tower from that switchover to past the incident.

It is correct that both cockpits were warned by Clearance Delivery of the similar callsign on frequency and both acknowledged it (kinda yeah-okayish, but they did acknowledge it). She even tells WN exactly what the "similar" DL callsign is.
 
nm2582
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 6:04 am

does ATC have the ability to reassign callsigns on the fly?

For example, at the first sign of confusion between two flights, could ATC do the following:

"
SouthWest 3828, your callsign is now SouthWest 3828 Alpha, do you copy?
...SouthWest 3828 Alpha copies
Delta 1328, your callsign is now Delta 1328 Bravo, do you copy?
... Delta 1328 Bravo copies
"

Seems like it might really help. But I don't know how well ATC systems are integrated or of it's easy to do such an update on the fly (or even technically feasible with the current system).

[Edited 2015-06-17 23:05:20]

[Edited 2015-06-17 23:06:20]
 
FighterPilot
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 6:09 am

Quoting nm2582 (Reply 23):

Unfortunately adding "Alpha" and "Bravo" to the end is not much different than them already being called "Delta" and "Southwest." The main problem lies in the similar flight numbers.

Cal   
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nm2582
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 6:25 am

Quoting FighterPilot (Reply 24):
Unfortunately adding "Alpha" and "Bravo" to the end is not much different than them already being called "Delta" and "Southwest." The main problem lies in the similar flight numbers.

I was kind of thinking about it from a human engineering standpoint - lots of people have no idea what you say before you say their name, but as soon as you say their name, they focus in and pay attention.

So I was thinking that perhaps it's the same with flight numbers. "blah blah blah 3828 (misheard as 1328) cleared for takeoff" vs. "blah blah blah 3828 (misheard as 1328) ALPHA cleared for takeoff.

If the theory is correct (that awareness of what's said after the flight number is much higher than what's said before, because the crew is "triggered" off the number), then they would have good odds of immediately recognizing the message is not for them (as they know that they aren't ALPHA).

I get that the crew is supposed to listen for the preceding company name in the callsign... it would be an interesting human engineering test to get a couple hundred pilots and simulate to see how many are mentally triggering just off the number.
 
ikramerica
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 6:32 am

Quoting FighterPilot (Reply 24):

The problem comes from parsing 1328 as thirteen twenty-eight rather than 1-3-2-8

1-3-2-8
And
3-8-2-8

Do not sound alike.
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 6:56 am

Quoting FighterPilot (Reply 24):
Unfortunately adding "Alpha" and "Bravo" to the end is not much different than them already being called "Delta" and "Southwest." The main problem lies in the similar flight numbers.

Why not address aircraft by their squawk instead? Less likelihood of having similar ones active from clearance delivery...
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737tdi
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 7:32 am

Quoting ikramerica (Reply 26):
The problem comes from parsing 1328 as thirteen twenty-eight rather than 1-3-2-8

1-3-2-8
And
3-8-2-8

Do not sound alike.

Exactly right. I am not a commercial pilot but am Taxi/Run qualified and taxi aircraft on a daily basis between the hangar and gates. All of our qualified mechs. are taught to communicate in this manner. We also use Southwest Maintenance instead of just Southwest to differentiate ourselves from the flight crews and we also use the tail no. as "seven niner two" as an example. More often then not the tower doesn't do this.
 
chrisair
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 8:09 am

I'm surprised these things don't happen more often. This controller at LAX has written a coupe fantastic blog posts about callsigns and flight numbers. http://fromthecontroltower.blogspot.com/2008/09/flight-one.html His story about UA69 and UA169 is a bit scary to think about.

Quoting FighterPilot (Reply 19):
As a corrective action will either carrier change their flight number to avoid this in the future, if so, who?

Probably. I'm sure the MDW tower crew will work with WN/DL to get it changed internally. WN changes flight numbers so frequently it probably won't be long until 3828 is changed anyway.

Quoting nm2582 (Reply 23):
does ATC have the ability to reassign callsigns on the fly?

This one is also good that shows how confusing it can be for controllers, and how he can deal with two similar callsigns:

http://fromthecontroltower.blogspot....09/for-real-this-time-decoded.html
 
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 10:57 am

Kinda reminds me of the incident a few years ago in DEN where some regional carrier made an emergency landing and evacuation, and the pilot just used the callsign "5912" (no airline), and the tower thought he was saying "United 12." Since ATC had no record of a "United 12" flight, they though it was some prankster with a radio and didn't properly respond to the emergency.
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sprout5199
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 12:35 pm

Quoting wjcandee (Reply 2):
A real call needs to be made for an end to the simplex voice communications in favor of the duplex system used by pretty much anyone with a decent radio these days. Ends the stepping on each other.

What do you mean a "Duplex" system? A "Full Duplex" system like in cell phones or a "Half-Duplex" like 2 way radios? either way it would not work for aircraft comms. Aircraft (and boats) need a simplex system, I.E. TX and RX on the same freq just for the fact that you don't need a tower in between two stations talking to each other. Think about that. If I need a radio tower to talk between an aircraft and a Controller or another aircraft, how many radio towers will that be? where will they be located? Just saying "they need to be Duplex like every body else" shows that you really don't understand how radio communications work. And this is not saying anything about cost. And as an airplane owner, cost is a big factor. I already hate that I HAVE to switch out my xponder for an "ADS-B out" one by 2020 to fly into controlled airspace. Im not made of money, even if my daughters think I am.

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trnswrld
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 3:29 pm

Just a note to some people above who stated it sounded like the controller was cut off or not clear. Remember, what you hear from a recording on liveatc is very different than what it actually sounds like in the cockpit or to the controller. These are just feeds from peoples scanners and there is no telling how far away they were from the transmitters and stuff like that. So again, just because a clearance might sound garbled, or blocked, or like static doesnt mean thats how it sounded to the pilot or controller.
 
FighterPilot
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 4:09 pm

Quoting nm2582 (Reply 25):
Quoting nm2582 (Reply 25):
I was kind of thinking about it from a human engineering standpoint - lots of people have no idea what you say before you say their name, but as soon as you say their name, they focus in and pay attention.

Very true, on the human factors side of things we as pilots get used to hearing what we expect to hear. You're sitting on an active runway waiting to go, 99.9% of the time ATC's next words to your are a takeoff clearance. So of course when you hear another takeoff clearance already you're ready to jump the gun.
Something I run into daily while flying in uncontrolled airspace is other aircraft making position report radio calls. Usually they go "Airline 123 is 25nm south of XYZ airport, 15,000, last off ABC expecting XYZ in 10 min." Being that you hear calls like this almost nonstop all the time in uncontrolled airspace, by the time you realize it could be a potential conflict your brain has forgotten what flight number the airline is, sometimes even what airline.
As airspace gets more and more crowded and amount of flight numbers increase eventually a new system may need to be implemented.
Similar to adding "Alpha" and "Bravo" to the end of flight numbers, they could have replaced 1328 with 1-3-2-Hotel, and leave 3828 as is. This way the numbers change, and a phonetic is added to the end to resolve ambiguity.

Cal   
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KarlB737
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 4:12 pm

Quoting bcoz (Reply 5):

What's strange to me is the fact that they were using two different runways for takeoffs. I've been flying in and out of MDW for more than ten years and I don't think I've seen that before. Arrivals on one runway and departures on another, yes.... but not simultaneous departures on intersecting runways.

I can relate to what bcoz has written. It has always been my observation at MDW that either 31C is active or 22L or 4R but never two that would intersect. Yes there was a call sign issue present in this instance but I think it is too risky for MDW to attempt two takeoffs in this fashion. If two planes ever collide at MDW at the intersection guess what the final ruling will be. It will state that there will be one and only one active runway for takeoffs.

That being said why not make that decision now before such a tragedy happens.
 
N766UA
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 4:49 pm

Quoting nm2582 (Reply 23):

No. However, in instances with similar-sounding callsigns, ATC should alert the aircraft to each other's callsigns, "Southwest 3828 be advised Delta 1328 on frequency," and then address each in the following manner: "Southwest 3828 Southwest" and "Delta 1328 Delta." This is standard procedure and it's in the 7110.

I haven't listened to the recording, but if the controller did not do this, he must have thought the callsigns were not "similar-sounding," however that obviously wasn't the case. Not blaming him by any means, but I'm sure there's going to be a similar-sounding callsigns briefing coming down the pike for everybody...

[Edited 2015-06-18 09:53:47]
 
Cubsrule
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 4:55 pm

Quoting KarlB737 (Reply 34):
Yes there was a call sign issue present in this instance but I think it is too risky for MDW to attempt two takeoffs in this fashion. If two planes ever collide at MDW at the intersection guess what the final ruling will be. It will state that there will be one and only one active runway for takeoffs.

Why is it any riskier than any other airport with operations on intersecting runways?
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jtamu97
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 5:15 pm

The only similarity is the last two digits of the call sign. This can be confusing in the private sector as most us are addressed November..... However, when you have the airline preceding the flight number it should be very clear. If these were two Southwest flights I could easily see where there may be some confusion.
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N766UA
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 5:25 pm

Quoting jtamu97 (Reply 37):

I promise you 2 digits is all you need.
 
wjcandee
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 6:07 pm

Quoting sprout5199 (Reply 31):
Just saying "they need to be Duplex like every body else" shows that you really don't understand how radio communications work.

Yeah, right. http://www.techrepublic.com/article/...-radio-communications-using-an-ic/

And, dumbass that I am, I must be the only person who has ever raised this issue. Oh. Wait. From 1999: http://www.aatl.net/publications/antiblocking.htm
 
wjcandee
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 6:16 pm

Quoting nm2582 (Reply 25):
blah blah blah 3828 (misheard as 1328) ALPHA cleared for takeoff.

Somebody (actually a committee of a bunch of somebodies) already thought this through, and what should have happened when ATC recognized the similar flight numbers: "Delta 1328 Delta". Here, Clearance Delivery picked up the issue and advised the pilots of it, but no telling whether Tower was aware of the issue before the conflict occurred. I suspect not, given that he said he was trying to figure out who was stepping on the transmissions. It would have been totally obvious to him had he had it in his head that there was potential confusion.

Maybe a procedure for Ground to advise TWR of the issue as the aircraft are transferred to him.
 
ikramerica
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 7:41 pm

Roger Roger, what's your vector Victor?

Oveur was over Unger, and Unger was under Dunn.


----

Might it also have been safer for the controller to simply keep the two flights off of the runways at the same exact time?
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OMP777X
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RE: WN-DL Close Call At MDW

Thu Jun 18, 2015 8:00 pm

Quoting IADCA (Reply 18):
There's a recording on liveatc with the full thing, and the warning was both directions. Both cockpits acknowledged the tower after being told there was a similar call sign on the frequency. The call sign mix up is the major contributing factor here, but it seems pretty clear the proximate cause is the DL pilots rolling without clearance. (And afterwards, the WN pilots even checked with the tower to make sure they were in the right, presumably to assist them in determining what to tell their employers.)

Thanks for the added info. I was just going off of what was played on the newscast, which apparently didn't include the whole story.
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SPREE34
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RE: WN-DL Close Call At MDW

Fri Jun 19, 2015 1:35 am

Quoting EA CO AS (Reply 27):
Why not address aircraft by their squawk instead? Less likelihood of having similar ones active from clearance delivery...

Not enough codes. 4096, and many of those are sub assigned to various terminal facilities and other functions. On a coast to coast, transponder codes are often changed because an aircraft in a given Center's airspace is already on the code you got coming out of the East coast.
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reltney
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RE: WN-DL Close Call At MDW

Fri Jun 19, 2015 2:01 pm

Same thing happened in CVG around 96. Planes just missed. Controller fault. As he heard the plane in error but thought it was to late to try and "abort" the errant aircraft. The report is interesting to read. I know one of you on airliners has the whole story..
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jetblastdubai
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RE: WN-DL Close Call At MDW

Fri Jun 19, 2015 3:23 pm

Quoting N766UA (Reply 35):
However, in instances with similar-sounding callsigns, ATC should alert the aircraft to each other's callsigns, "Southwest 3828 be advised Delta 1328 on frequency," and then address each in the following manner: "Southwest 3828 Southwest" and "Delta 1328 Delta." This is standard procedure and it's in the 7110

I won't comment on this incident specifically because without knowing all the details, no one can make a conclusive assessment of what or how things happened. I will, however post the regs that address similar-sounding callsigns as well as add some insight on some of the other suggestions made on this thread so far.

The exact wording from the 7110.65:

"2−4−15. EMPHASIS FOR CLARITY Emphasize appropriate digits, letters, or similar sounding words to aid in distinguishing between similar sounding aircraft identifications. Additionally: a. Notify each pilot concerned when communicating with aircraft having similar sounding identifications.

EXAMPLE− “United Thirty−one United, Miami Center, U.S. Air Thirty−one is also on this frequency, acknowledge.” “U.S. Air Thirty−one U.S. Air, Miami Center, United Thirty−one is also on this frequency, acknowledge.

Para 2−1−13, Aircraft Identification Problems.
b. Notify the operations supervisor−in-charge of any duplicate flight identification numbers or phonetically similar-sounding call signs when the aircraft are operating simultaneously within the same sector."

Frequent problems with similar-sounding callsigns have become a major issue with ATC since the advent of 4-digit flight numbers that reared their ugly heads at first with the Express carriers. (this is why using the squawk code for identification would be terrible and adding a letter to a 4-digit callsign would be even worse). For example, back in the 80's when Eagle was becoming big at ORD, every one of their flight numbers started with a "4". (ie. 4223, 4323, 4322 etc). The first digit "4" did absolutely nothing to help differentiate flights from each other so we (FAA) asked Eagle to simply drop the "4" from their ATC callsigns and use just the last 3 digits. Problem solved.

With airline mergers and consolidations, it is now impossible to simply drop the first digit because carriers have now become so big that all their flights cannot be accommodated by the remaining 3-digit callsigns. I participated on several work groups addressing communications and human factors issues with the FAA, NASA ASRS and the Volpe Center ( http://www.volpe.dot.gov/ ) and actually came up with a workable procedure to just about completely eliminate the 4-digit call signs and greatly reduce the similar-sounding callsign problems in the ATC system.

I forwarded this procedure on to a couple of the regional carriers at the time and one of them actually adopted it within a few weeks. It worked like a charm for pilots and controllers. The increased workload came from the dispatchers or the people that actually filed the flight plans as they had to convert the "airline flight number" to an "ATC flight number" using a simple conversion chart. Every 4-digit callsign could be converted to a "2-digit plus a single letter" callsign.

It's actually a rather simple conversion process and I'd be happy to show it if anyone's interested but I don't want to hijack this whole thread. PM me if you're interested or it might be worth a whole new thread if there's enough interest in the topic.
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Cubsrule
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RE: WN-DL Close Call At MDW

Fri Jun 19, 2015 3:53 pm

Quoting jetblastdubai (Reply 45):
With airline mergers and consolidations, it is now impossible to simply drop the first digit because carriers have now become so big that all their flights cannot be accommodated by the remaining 3-digit callsigns.

For a while (mid-00s) MQ was large enough that the 3-digit flight numbers were inadequate, but they recycled 3-digit flight numbers for flights that were geographically and/or chronologically far apart. The system was not perfect, though; I recall that DFW-VPS and ORD-JAX had the same callsign for a while (one's flight number was 3XYZ and the other's was 4XYZ) and arrived around the same time, and that was a little close for comfort.

The irony here is that we laud WN for not outsourcing any flying, but that forces WN to use 4-digit callsigns even though a typical WN callsign applies to many more flights than a typical callsign on most other carriers.
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