Very close call at Minneapolis - Airliners.net

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Moderator

Re: Very close call at Minneapolis

Fri Jun 16, 2023 10:45 pm

Gonzalo wrote:

If already reported mods please remove.

https://avherald.com/h?article=50a8a110&opt=0

Quote : ADS-B data suggest, the separation between the aircraft, both airborne at 23:29:03Z, reduced to about

200 feet vertical and 0.14nm horizontal.

That sounds awfully close...

"ADS-B data suggest..." If they're measuring based on publicly available ADS-B data, then it may not be accurate. The article also lacks context — what were the weather conditions? What type of approach was issued? Was visual separation applied? It's difficult to draw many conclusions at this point. Obviously they got close, but it's difficult to say if there was a procedural breakdown without more information. That's not to say that this isn't worth discussing, but without more, it's difficult to discuss on a factual basis.

Re: Very close call at Minneapolis

Fri Jun 16, 2023 11:36 pm

atcsundevil wrote:

Gonzalo wrote:

If already reported mods please remove.

https://avherald.com/h?article=50a8a110&opt=0

Quote : ADS-B data suggest, the separation between the aircraft, both airborne at 23:29:03Z, reduced to about

200 feet vertical and 0.14nm horizontal.

That sounds awfully close...

"ADS-B data suggest..." If they're measuring based on publicly available ADS-B data, then it may not be accurate. The article also lacks context — what were the weather conditions? What type of approach was issued? Was visual separation applied? It's difficult to draw many conclusions at this point. Obviously they got close, but it's difficult to say if there was a procedural breakdown without more information. That's not to say that this isn't worth discussing, but without more, it's difficult to discuss on a factual basis.

Avherald also notes the wrong aircraft type for what registration they claim is involved. Should be a 223.

Re: Very close call at Minneapolis

Fri Jun 16, 2023 11:50 pm

atcsundevil wrote:

Gonzalo wrote:

If already reported mods please remove.

https://avherald.com/h?article=50a8a110&opt=0

Quote : ADS-B data suggest, the separation between the aircraft, both airborne at 23:29:03Z, reduced to about

200 feet vertical and 0.14nm horizontal.

That sounds awfully close...

"ADS-B data suggest..." If they're measuring based on publicly available ADS-B data, then it may not be accurate. The article also lacks context — what were the weather conditions? What type of approach was issued? Was visual separation applied? It's difficult to draw many conclusions at this point. Obviously they got close, but it's difficult to say if there was a procedural breakdown without more information. That's not to say that this isn't worth discussing, but without more, it's difficult to discuss on a factual basis.

There’s zero reason the public ADSB data would be wrong. It’s just a ground ADSB receiver getting the exact readout from the plane.

Moderator

Re: Very close call at Minneapolis

Sat Jun 17, 2023 2:20 am

777Mech wrote:

Avherald also notes the wrong aircraft type for what registration they claim is involved. Should be a 223.

The A220 is still formally registered as a C-Series. They are filed as "BCS1" and "BCS3". The Airbus A220 effectively only exists in branding.

32andBelow wrote:

There’s zero reason the public ADSB data would be wrong. It’s just a ground ADSB receiver getting the exact readout from the plane.

Re: Very close call at Minneapolis

Sat Jun 17, 2023 3:12 am

Seems to me that’s there’s too much assuming that things will go perfectly right. There was a way out in this case but… that was close.

Re: Very close call at Minneapolis

Sat Jun 17, 2023 4:15 am

atcsundevil wrote:

777Mech wrote:

Avherald also notes the wrong aircraft type for what registration they claim is involved. Should be a 223.

The A220 is still formally registered as a C-Series. They are filed as "BCS1" and "BCS3". The Airbus A220 effectively only exists in branding.

The C-Series is, itself, just branding as well. While flight plans read "BCS1" or "BCS3," the airplane is technically a Bombardier BD-500!

Last edited by

on Sat Jun 17, 2023 4:16 am, edited 1 time in total.

Re: Very close call at Minneapolis

Sat Jun 17, 2023 4:15 am

This was all over the local news in MSP today. Apparently being investigated by the FAA. A number of well known spotters were at the airport when this happened and many on the facebook group noted the aircraft looked so close they thought they would collide. Not sure why MSP has so many of these issues but it was at one time, if I remember correctly, the airport in the US with the highest number of incursions.

Jeremy

Re: Very close call at Minneapolis

Sat Jun 17, 2023 9:06 am

[photoid][/photoid]

N766UA wrote:

atcsundevil wrote:

777Mech wrote:

Avherald also notes the wrong aircraft type for what registration they claim is involved. Should be a 223.

The A220 is still formally registered as a C-Series. They are filed as "BCS1" and "BCS3". The Airbus A220 effectively only exists in branding.

The C-Series is, itself, just branding as well. While flight plans read "BCS1" or "BCS3," the airplane is technically a Bombardier BD-500!

I know, My point is that N311DU is a -300, not a -100.

Re: Very close call at Minneapolis

Sat Jun 17, 2023 8:31 pm

I witnessed this from the delta club. There was about 5 seconds of separation. It was like watching a vertical drag race. the American made no effort to change directions

Re: Very close call at Minneapolis

Sat Jun 17, 2023 10:50 pm

SESGDL wrote:

This was all over the local news in MSP today. Apparently being investigated by the FAA. A number of well known spotters were at the airport when this happened and many on the facebook group noted the aircraft looked so close they thought they would collide. Not sure why MSP has so many of these issues but it was at one time, if I remember correctly, the airport in the US with the highest number of incursions.

Jeremy

Any known photos of this incident from the spotters?

Moderator

Re: Very close call at Minneapolis

Sun Jun 18, 2023 12:59 am

777Mech wrote:

[photoid][/photoid]

N766UA wrote:

atcsundevil wrote:

The A220 is still formally registered as a C-Series. They are filed as "BCS1" and "BCS3". The Airbus A220 effectively only exists in branding.

The C-Series is, itself, just branding as well. While flight plans read "BCS1" or "BCS3," the airplane is technically a Bombardier BD-500!

I know, My point is that N311DU is a -300, not a -100.

I see what you're saying. Well I guess nobody is sure what to call it

Topic Author

Re: Very close call at Minneapolis

Sun Jun 18, 2023 2:12 pm

daemonizer wrote:

I witnessed this from the delta club. There was about 5 seconds of separation. It was like watching a vertical drag race. the American made no effort to change directions

Ufff... I guess you felt a chill running through your spine watching that !.... It will be great if some survelliance camera recorded the incident....or one of the - now - popular youtube channels streaming live from the busiest airports. From you point of observation, was the AA pilot in a position to keep the other aircraft insight at all times? Maybe he/she didn't make any change of heading because the other aircraft was already in his/her sight?

Re: Very close call at Minneapolis

Sun Jun 18, 2023 2:21 pm

questions wrote:

SESGDL wrote:

This was all over the local news in MSP today. Apparently being investigated by the FAA. A number of well known spotters were at the airport when this happened and many on the facebook group noted the aircraft looked so close they thought they would collide. Not sure why MSP has so many of these issues but it was at one time, if I remember correctly, the airport in the US with the highest number of incursions.

Jeremy

Any known photos of this incident from the spotters?

I haven’t seen any posted, unfortunately.

Jeremy

Re: Very close call at Minneapolis

Sun Jun 18, 2023 3:29 pm

Gonzalo wrote:

daemonizer wrote:

I witnessed this from the delta club. There was about 5 seconds of separation. It was like watching a vertical drag race. the American made no effort to change directions

From you point of observation, was the AA pilot in a position to keep the other aircraft insight at all times? Maybe he/she didn't make any change of heading because the other aircraft was already in his/her sight?

Well I saw on ADS-B that the AA aircraft did move off to the left a little bit, so maybe. But It was too little to see from ground level. Personally I think the American's biggest fault was not executing a climb out imo

Re: Very close call at Minneapolis

Sun Jun 18, 2023 5:07 pm

atcsundevil wrote:

777Mech wrote:

Avherald also notes the wrong aircraft type for what registration they claim is involved. Should be a 223.

The A220 is still formally registered as a C-Series. They are filed as "BCS1" and "BCS3". The Airbus A220 effectively only exists in branding.

32andBelow wrote:

There’s zero reason the public ADSB data would be wrong. It’s just a ground ADSB receiver getting the exact readout from the plane.

I can't even count the number of times I've seen erroneous ADS-B data from public receivers, because they'll receive bad hits particularly at low altitude. There have been dozens of threads created here over the years because of erroneous or inaccurate public ADS-B data. The agency doesn't use ADS-B to measure target distances in investigations anyway, so it doesn't really matter until there's an official number and percentage of separation.

We use ADSB to separate just off the ground so I don’t know what the difference would be

Re: Very close call at Minneapolis

Sun Jun 18, 2023 5:31 pm

Tapes from LiveATC are up on YouTube.

Local controller had a SCX with a flow time taxiing down 30L to make A3 exit, puts the DAL BCS3 in position but there's just not enough time. DAL starts rolling, controller sends AAL around with "go around, right side, runway 30L," and then seems confused and says "AAL2406, I thought you were going on the right side, sir."

No diverging headings given until well into the incident, so yeah, this one was real, real close I'd say. Sounds like a loss of situational awareness, especially with the consistent, correct references to 30L, and then the confusion about "the right side."

Weather wasn't very good either, this could easily have been a mid-air.

Topic Author

Re: Very close call at Minneapolis

Sun Jun 18, 2023 5:38 pm

daemonizer wrote:

Gonzalo wrote:

daemonizer wrote:

I witnessed this from the delta club. There was about 5 seconds of separation. It was like watching a vertical drag race. the American made no effort to change directions

From you point of observation, was the AA pilot in a position to keep the other aircraft insight at all times? Maybe he/she didn't make any change of heading because the other aircraft was already in his/her sight?

Well I saw on ADS-B that the AA aircraft did move off to the left a little bit, so maybe. But It was too little to see from ground level. Personally I think the American's biggest fault was not executing a climb out imo

Ok, many thanks for your feedback and first hand impressions. I don't want to sound like a mediocre journalist making storms in a cup of water, but the number of incursions and near misses ( or "near hits" like the unforgettable George Carlin would say ) is becoming alarming...or maybe the average number of incidents is the same but now we are more aware compared to preCovid era, I don't know. Glad that for now, only ink has been spilled in incident investigation reports and not blood in a crash, let's hope the string of incidents raise the eyebrows of all the people involved in aviation safety and nothing more serious happen. Best Regards!

G.

Re: Very close call at Minneapolis

Sun Jun 18, 2023 5:55 pm

I've seen more ATC errors in the last 3 years than probably ever. The approach controller and tower don't see to be able to work together anymore in lots of cities. I think it's a combo of being short of help and new people in both ATC plus lots of new pilots in new equipment.

Re: Very close call at Minneapolis

Sun Jun 18, 2023 7:37 pm

NLINK wrote:

I've seen more ATC errors in the last 3 years than probably ever. The approach controller and tower don't see to be able to work together anymore in lots of cities. I think it's a combo of being short of help and new people in both ATC plus lots of new pilots in new equipment.

Or more means of finding about them like live atc, flight trackers, social media, and regular media now having a hard on for aviation.

Re: Very close call at Minneapolis

Sun Jun 18, 2023 8:27 pm

32andBelow wrote:

atcsundevil wrote:

777Mech wrote:

Avherald also notes the wrong aircraft type for what registration they claim is involved. Should be a 223.

The A220 is still formally registered as a C-Series. They are filed as "BCS1" and "BCS3". The Airbus A220 effectively only exists in branding.

32andBelow wrote:

There’s zero reason the public ADSB data would be wrong. It’s just a ground ADSB receiver getting the exact readout from the plane.

I can't even count the number of times I've seen erroneous ADS-B data from public receivers, because they'll receive bad hits particularly at low altitude. There have been dozens of threads created here over the years because of erroneous or inaccurate public ADS-B data. The agency doesn't use ADS-B to measure target distances in investigations anyway, so it doesn't really matter until there's an official number and percentage of separation.

We use ADSB to separate just off the ground so I don’t know what the difference would be

The difference is ATC ADSB receivers are at a height to maintain line of site with the airframe, usually co-located with PSR/SSR. The amateur receivers used the by FR24 and others are usually in someone’s house or shed….somewhere……and might not necessarily have line of sight, thus the accuracy is not to be trusted.

Re: Very close call at Minneapolis

Sun Jun 18, 2023 9:28 pm

There are numerous issues that can arise in ADS-B transmissions. One is GPS error, which commercial avionics evaluate and attempt to filter out. Another is altitude which may require ambient pressure compensation. Another may be transmission packet dropout & errors, resulting in inconsistent data. All these need to be checked to determine a final accurate position and trajectory.

Last edited by

on Sun Jun 18, 2023 9:30 pm, edited 1 time in total.

Re: Very close call at Minneapolis

Sun Jun 18, 2023 9:29 pm

HTCone wrote:

The amateur receivers used the by FR24 and others are usually in someone’s house or shed….somewhere……and might not necessarily have line of sight, thus the accuracy is not to be trusted.

I'm unclear how you reach this conclusion. It seems to me that each ADSB Out data packet, which is generated aboard the subject aircraft and then transmitted, and would be used to show an aircraft's position, has all the information necessary, including time, for ground equipment to plot the aircraft's position, regardless of where the receiver is located. Being digital data, it would seem that if the receiver can receive it accurately, it's not likely to be "untrustworthy".

I could be completely-wrong here, but it sounds similar to the misconception that you need 3 different receivers to receive the data before it can be used.

Re: Very close call at Minneapolis

Sun Jun 18, 2023 11:55 pm

As a former MSP employee this happens a lot. Maybe a little to close. I saw the 747 get waved off one afternoon, while at Term 2...oh it was very low.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 7:42 am

tjerome wrote:

https://www.youtube.com/watch?v=1T8ER-a87_c

Well, it looks like the AA pilot didn’t follow the instructions to go on the right side. If he had, the planes would have gone in opposite directions. Of course, should the DL plane have been cleared to roll if the AA plane is so close?

Re: Very close call at Minneapolis

Mon Jun 19, 2023 7:42 am

tjerome wrote:

https://www.youtube.com/watch?v=1T8ER-a87_c

This seems like a combination of factors involved.

The overall spacing by ATC was tight to begin with, then for the SunWing runway taxi, ATC had to ask them to expedite as they were dawdling.

Then American responded to the ATC instruction to go-around on the right, with "on the go", leaving out the right side confirmation.

When challenged by ATC for not being on the right side, American responded they thought he had said left, and apologized.

This seems like the usual sequence of cascading errors that define accident situations.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 8:45 am

Avatar2go wrote:

There are numerous issues that can arise in ADS-B transmissions. One is GPS error, which commercial avionics evaluate and attempt to filter out. Another is altitude which may require ambient pressure compensation. Another may be transmission packet dropout & errors, resulting in inconsistent data. All these need to be checked to determine a final accurate position and trajectory.

I’ve correlated radar with FR24 and have never seen an anomaly

Re: Very close call at Minneapolis

Mon Jun 19, 2023 8:52 am

wjcandee wrote:

HTCone wrote:

The amateur receivers used the by FR24 and others are usually in someone’s house or shed….somewhere……and might not necessarily have line of sight, thus the accuracy is not to be trusted.

I'm unclear how you reach this conclusion. It seems to me that each ADSB Out data packet, which is generated aboard the subject aircraft and then transmitted, and would be used to show an aircraft's position, has all the information necessary, including time, for ground equipment to plot the aircraft's position, regardless of where the receiver is located. Being digital data, it would seem that if the receiver can receive it accurately, it's not likely to be "untrustworthy".

I could be completely-wrong here, but it sounds similar to the misconception that you need 3 different receivers to receive the data before it can be used.

No, you need line of sight between the transmitter and the receiver. An amateur receiver in somebody’s shed will likely lose that vs one used by ATC on top of a mast or mountain. If there is any terrain or tall building between the receiver and transmitter, signal will be lost. ADSB requires line of sight to work, just like civilian PSR, SSR and VHF. I’m not talking about MLAT or similar. ADSB data from FR24 etc is inherently unreliable because whenever the amateur receiver it has been obtaining data from loses line of sight and no other feed is available, it starts to guess.

Last edited by

on Mon Jun 19, 2023 8:55 am, edited 1 time in total.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 8:54 am

32andBelow wrote:

I’ve correlated radar with FR24 and have never seen an anomaly

That's great. I'm just quoting the guideline documents for integrating ADS-B into ATC operations, which require checking & adjustment of all those parameters before they can be displayed to controllers as valid data.

The same level of care is taken for FAA and NTSB investigations, and establishment of true positions and trajectories.

However none of that is being done by FR24, unless they explicitly state the data are corrected. That's the difference between the public grade of data they provide, and professional grade that is used by ATC, FAA, and NTSB.

For NTSB preliminary reports, you will often see them state they are using public ADS-B data, as they have not yet reviewed, correlated, and corrected all the data.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 9:05 am

Avatar2go wrote:

32andBelow wrote:

I’ve correlated radar with FR24 and have never seen an anomaly

That's great. I'm just quoting the guideline documents for integrating ADS-B into ATC operations, which require checking & adjustment of all those parameters before they can be displayed to controllers as valid data.

The same level of care is taken for FAA and NTSB investigations, and establishment of true positions and trajectories.

However none of that is being done by FR24, unless they explicitly state the data are corrected. That's the difference between the public grade of data they provide, and professional grade that is used by ATC, FAA, and NTSB.

For NTSB preliminary reports, you will often see them state they are using public ADS-B data, as they have not yet reviewed, correlated, and corrected all the data.

And what are the chances of losing line do site in Minneapolis. Maybe there can be anomalies. But chances are it’s correct. That being said if they were applying visual separation then it doesn’t really matter how close they got.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 9:26 am

32andBelow wrote:

And what are the chances of losing line do site in Minneapolis. Maybe there can be anomalies. But chances are it’s correct. That being said if they were applying visual separation then it doesn’t really matter how close they got.

The line of sight issue only arises in the context of erroneous or inconsistent data, out of sequence packets, etc. Another issue is the moving sources, which can introduce phase errors. The protocols are designed to minimize this, but errors can still occur.

In wireless data networks, these are very common issues, but the networks use handshaking and retransmission as compensatory mechanisms. With ADS-B, there is no handshaking as it's receive only.

However it does use some of the same bit correction techniques as wireless data. It's just important to understand those methods are not infallible. Nor is GPS, for that matter. And since they are both receive only, all the correction has to occur downstream.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 10:00 am

wjcandee wrote:

It seems to me that each ADSB Out data packet, which is generated aboard the subject aircraft and then transmitted, and would be used to show an aircraft's position, has all the information necessary, including time, for ground equipment to plot the aircraft's position, regardless of where the receiver is located.

ADS-B position messages do not include a timestamp. (They don't even include a complete GPS position. You need to receive two ADS-B position messages in order to get an unambiguous position value. These messages are very small.)

Each position message does include a single bit indicating whether or not the reported position is synchronized with GPS seconds. That doesn't tell you *which* GPS second it matches unless the receiver is also synchronized with GPS time and can correctly compensate for its own internal latency.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 10:59 am

32andBelow wrote:

Avatar2go wrote:

32andBelow wrote:

I’ve correlated radar with FR24 and have never seen an anomaly

That's great. I'm just quoting the guideline documents for integrating ADS-B into ATC operations, which require checking & adjustment of all those parameters before they can be displayed to controllers as valid data.

The same level of care is taken for FAA and NTSB investigations, and establishment of true positions and trajectories.

However none of that is being done by FR24, unless they explicitly state the data are corrected. That's the difference between the public grade of data they provide, and professional grade that is used by ATC, FAA, and NTSB.

For NTSB preliminary reports, you will often see them state they are using public ADS-B data, as they have not yet reviewed, correlated, and corrected all the data.

And what are the chances of losing line do site in Minneapolis. Maybe there can be anomalies. But chances are it’s correct. That being said if they were applying visual separation then it doesn’t really matter how close they got.

Pretty good chance at low altitude if the receiver was more than a couple of miles from the airfileld actually. Church steeples, apartment buildings, water towers, trees, evening neighbouring houses, anything remotely tall will block the signal once the aircraft is at low altitude. People put way too much faith at times in FR24. I've walked away from my sector on break previously and checked FR24 out of curiosity, it has often shown aircraft at incorrect flight levels, routings etc because whatever ground receiver they were relying on is obviously out of range, sight or just not well set up.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 12:03 pm

HTCone wrote:

32andBelow wrote:

Avatar2go wrote:

The same level of care is taken for FAA and NTSB investigations, and establishment of true positions and trajectories.

However none of that is being done by FR24, unless they explicitly state the data are corrected. That's the difference between the public grade of data they provide, and professional grade that is used by ATC, FAA, and NTSB.

For NTSB preliminary reports, you will often see them state they are using public ADS-B data, as they have not yet reviewed, correlated, and corrected all the data.

And what are the chances of losing line do site in Minneapolis. Maybe there can be anomalies. But chances are it’s correct. That being said if they were applying visual separation then it doesn’t really matter how close they got.

Pretty good chance at low altitude if the receiver was more than a couple of miles from the airfileld actually. Church steeples, apartment buildings, water towers, trees, evening neighbouring houses, anything remotely tall will block the signal once the aircraft is at low altitude. People put way too much faith at times in FR24. I've walked away from my sector on break previously and checked FR24 out of curiosity, it has often shown aircraft at incorrect flight levels, routings etc because whatever ground receiver they were relying on is obviously out of range, sight or just not well set up.

Considering you can see all the planes taxing around I thinning their coverage is quite subburb! The way y’all are making the reliability of ADSB out im surprised it’s allowed to be used for in cockpit traffic advisories!

Re: Very close call at Minneapolis

Mon Jun 19, 2023 12:12 pm

32andBelow wrote:

Considering you can see all the planes taxing around I thinning their coverage is quite subburb! The way y’all are making the reliability of ADSB out im surprised it’s allowed to be used for in cockpit traffic advisories!

The in-cockpit applications of ADS-B require being within range of a ground station, that transmits the scrubbed and corrected data. It's of higher quality than the raw FR24 data.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 1:18 pm

NLINK wrote:

I've seen more ATC errors in the last 3 years than probably ever. The approach controller and tower don't see to be able to work together anymore in lots of cities. I think it's a combo of being short of help and new people in both ATC plus lots of new pilots in new equipment.

Actually a great number of facilities have split Tower and TRACON years ago. IIRC, IAH Tower and TRACON split our operations back in 1992 or 1993 and we were not the first to have eliminated the upstairs one shift, downstairs the next etc. So, not a new item.

Yes staffing in facilities is an issue and has been for some time. When I retired in 2012, we had many hours of overtime due to staffing, so again not a new issue.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 2:00 pm

VS11 wrote:

tjerome wrote:

https://www.youtube.com/watch?v=1T8ER-a87_c

Well, it looks like the AA pilot didn’t follow the instructions to go on the right side. If he had, the planes would have gone in opposite directions. Of course, should the DL plane have been cleared to roll if the AA plane is so close?

Transitioning from landing to go around is a momentary very high workload situation for the pilots. They're not going to absorb really any instructions other than the "go around" call. Not to mention "right side" isn't standard phraseology and mixed in with the "30 LEFT."

The controller needed to say something like "Turn right immediately"... this was a confusing instruction when the pilots highly task loaded.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 2:06 pm

mikejepp wrote:

VS11 wrote:

tjerome wrote:

https://www.youtube.com/watch?v=1T8ER-a87_c

Well, it looks like the AA pilot didn’t follow the instructions to go on the right side. If he had, the planes would have gone in opposite directions. Of course, should the DL plane have been cleared to roll if the AA plane is so close?

Transitioning from landing to go around is a momentary very high workload situation for the pilots. They're not going to absorb really any instructions other than the "go around" call. Not to mention "right side" isn't standard phraseology and mixed in with the "30 LEFT."

The controller needed to say something like "Turn right immediately"... this was a confusing instruction when the pilots highly task loaded.

Sure, it is a high-workload situation without doubt. But aren't the GA procedures very specific which direction to turn at what altitude? I would have expected the pilot to know which direction to GA even if the controller didn't say the direction. Probably, the pilot did know it but thought he was instructed otherwise.

Moderator

Re: Very close call at Minneapolis

Mon Jun 19, 2023 2:09 pm

Avatar2go wrote:

32andBelow wrote:

Considering you can see all the planes taxing around I thinning their coverage is quite subburb! The way y’all are making the reliability of ADSB out im surprised it’s allowed to be used for in cockpit traffic advisories!

The in-cockpit applications of ADS-B require being within range of a ground station, that transmits the scrubbed and corrected data. It's of higher quality than the raw FR24 data.

Exactly, and as HTCone noted, the unreliability factor isn't ADS-B, it's the receivers. Obviously the receivers that are collocated with radar sites are going to be highly accurate and usable for separation, but that isn't the feed that FR24 receives. They're using user supplied receivers from locations ideally close to major airports, but still limited by line of sight. FR24 is coded to fill in the gaps if there are unreliable hits, but those gaps are estimated points rather than actual points when the FR24 receiver doesn't receive a return, but the anomalies become magnified closer to the surface because of more dramatic increases in altitude, speed, and heading and the liklihood of bad hits due to the loss of line of sight.

Again, that's not to say that the numbers provided are wrong, just that I'm skeptical of the reliability of those numbers until official numbers are available. Accurate numbers simply aren't possible using non-official sources, regardless of their perceived accuracy.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 2:22 pm

This incident is similar to the AUS conflict between the FedEx 767 and the Southwest 737 in that they both involved very rushed operations at airports that are not that busy. Because of upguaging, and with 739s and 321s operating so many flights out of MSP, we have tons of breaks in arrivals and departures throughout the day. So does AUS. There is zero reason that they needed to wedge that A220 departure in front of that American 737 on short final. Ditto at AUS, as they put the Southwest flight out in front of the FedEx (which was performing an autoland in very low visibility) with no one behind the Southwest waiting for departure. Upgauging means fewer movements, and there is plenty of time to separate airplanes and keep things safe.

Re: Very close call at Minneapolis

Mon Jun 19, 2023 3:04 pm

VS11 wrote:

tjerome wrote:

https://www.youtube.com/watch?v=1T8ER-a87_c

Well, it looks like the AA pilot didn’t follow the instructions to go on the right side. If he had, the planes would have gone in opposite directions. Of course, should the DL plane have been cleared to roll if the AA plane is so close?

That's not a valid instruction. I have literally no idea what he meant in that go around instruction - apparently it's GFK VFR tower phraseology. Controller came from GFK, an extremely heavy flight training airport, and gave a 737 locally understood VFR tower go around instructions.

You can't "go around right side" when you're on a half mile final and the "right side" is 2000 feet to your right. Not to mention, doesn't solve the proximate problem, both aircraft needed headings to start diverging. I can only imagine the delay was accompanied by staring out the window at 30L and the two aircraft (this end of 30L is right out of the tower window) and hoping they don't hit. This whole incident occurred in *prominent* view for anyone in the ATCT.

Lost situational awareness, then panicked, and fell back on previously demonstrated competencies. There are thousands dead in aviation because of this sort of thing, it happens all the time.

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