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Near miss with 5 airliners waiting for T/O on taxiway "C" in SFO!

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Near miss with 5 airliners waiting for T/O on taxiway "C" in SFO!

Old 31st Jul 2017, 20:36
  #521 (permalink)  
 
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My god I hope that ends this madness.

(although it was AC that provided all of the entertainment) Peekay, do you work for AC?
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Old 1st Aug 2017, 15:52
  #522 (permalink)  
 
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not sure why there seems so much confusion over whether ATC called for GA first or not

in the play back of the ATC tape the United flight on taxiway C end waiting for his take off clearly calls (at 15.5 seconds after AC759 queries some lights on 'his runaway') ''wheres this guy goin'' then 3.5 seconds later United calls again ''he's on the taxiway''
(this is now about 20 seconds after AC759 first questions the lights he sees ahead)

then 4.5 seconds later ATC calls for AC759 to go around,
and AC759 immediately replies (now 29 seconds after his first query of lights ahead) ''IN the go around'' - the word IN and his tone implying I am already doing this (supposition on my part)


that implies to me he was already overshooting - if he was not already then I think he would have hit the aircraft waiting - that's my tuppence and I heard that the first day of the released tape which is on Page one of this thread.

in the 29 seconds of tape recording (and 29 seconds seems quite a long time to me) from AC759 first query of lights ahead to him calling 'in the go around'

how far do you fly and descend in that time ?

Last edited by rog747; 3rd Aug 2017 at 07:30.
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Old 1st Aug 2017, 18:25
  #523 (permalink)  
 
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Just to drift away from the circular discusssion a little, I wonder what was the effect on those a/c, waiting innocently on the taxiway, of the thrust pouring out of the rear end of rapid full umph GA. I'd expect 'storm force a lot' buffeting those beasts, and scaring the poo out of the pax who could see & hear nothing. Well, up to that point anyway. I guess they heard it. If they did get a ground based ride in a washing machine I wonder what the capatins said by way of explanation.
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Old 1st Aug 2017, 22:28
  #524 (permalink)  
 
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Rat 5,

That is a very good point, United looked to be about 45 to the flightpath, so the pax got a real good view, the other acs, especially #2, had a very, very good view of an ac less than 50 feet above them, heading to the windscreen...damn, that must have been quite the experience.
Funny how it is always the lowest common denominator that exposes the weaknesses in a system.

Many discussions in the ATM circles on this with the move to automation of towers and remote towers. Especially how worthless ADSB is on final.
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Old 2nd Aug 2017, 01:52
  #525 (permalink)  
 
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Looks good in Aviation Leak (Week). As you suggest, not nearly ready for prime time.

We (as in the U.S.) haven't really solved the problem of a 737 landing atop a commuter carrier at LAX, or, for that matter, assuring the runway is clear at an LAX when I am making a CAT III autoland in RVR 600 conditions.
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Old 2nd Aug 2017, 02:59
  #526 (permalink)  
 
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I have been looking at multiple 'tower' setups from different suppliers in the last few days, I just wonder how this has gotten so much traction, while some of the basics have lanquished.
ADSB mandate is going to be delayed yet again in the US, so while that is not really a viable method of tracking in the terminal environment, there is no other solution being looked at.
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Old 2nd Aug 2017, 11:03
  #527 (permalink)  
 
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Night visual= ILS 4miles, END OFF!

Hi All.
Been away , doing some semi longhaul with fuelstop and a 180. Been without my prune code and just taken in all the latest ANTSB analysis . ( A= armchair).
Also did the sim and reviewed the different GPS based approaches we can and can not do.

Considering some companies do not let you do a visual at night and in some country it is prohibited, I think it is fair to propose that if a visual is executed, the ILS must be tuned idented and briefed.I dont much care how that is done in a stoneage non GPS A320, just do it!


So for the 4 time from me, to avoid making the biggest airline accident EVER:
A KISS at night, Eh!
The last S beeing the most important!
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Old 2nd Aug 2017, 14:32
  #528 (permalink)  
 
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Originally Posted by aterpster View Post
Looks good in Aviation Leak (Week). As you suggest, not nearly ready for prime time.

We (as in the U.S.) haven't really solved the problem of a 737 landing atop a commuter carrier at LAX, or, for that matter, assuring the runway is clear at an LAX when I am making a CAT III autoland in RVR 600 conditions.
On the contrary, the problem has been solved in different ways several times. I have worked with one that was a distributed radar systems that could show and track individual pedestrians and the display was set up like a full airport simulator allowing the ground controller to zoom a point of presence anywhere on the airport and aircraft and vehicles were shown as 3D models of the aircraft/vehicle being picked up and tracked by the radar.
But as it would never happen that an aircraft could land on an occupied runway or taxiway - it wasn't seen as something necessary . Out of some of that research came Aerobahn by SAAB/SENSIS

Aerobahn Now Available for iPad and Android Tablets
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Old 2nd Aug 2017, 16:27
  #529 (permalink)  
 
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Ian, how can you say that the problem has been solved, when you also say that it was not necessary to include provisions for tracking the ac to prevent landing on the taxiway? The information provided by the FAA's Surface Movement Event Service showed the ac was lined up with the taxiway, along with the altitudes, yet this system provided no alert, nor did the systems it feeds data to, ASDEX or in this case, ASSC? How can one provide runway conflict warning when incoming ac are not tracked?

Care to guess who provides these systems? (and the one at SFO?)
U.S. Federal Aviation Administration selects Saab Sensis for Airport Surface Surveillance Capability Program

The Saab/Sensis system does not appear to have provisions for tracking which runway or taxiway the ac is landing, and alert/prevent. As far as I can tell, the Sensis system is really for ground ops, not a combination. How can one provide runway conflict warning when incoming ac are not tracked?


The system at SFO was supposed to be tracking inbound ac to 5nm with option for 20nm, yet it failed to alert the controller. For all we know, the ac could have been lined up on 28L instead of the taxi, what is, or even, is there an alert algorithm?

It was the prototype, and is supposed to be deployed at other airports in the US. Again, it is good that we had a lowest common denominator (airline with history of landing on taxiways) test of the system so that it is fixed and not deployed throughout the network.

It is interesting because NAVCANADA has an ATM ground track management system for tower ops that does track inbound aircraft when the threshold is obscured from tower.

Last edited by underfire; 2nd Aug 2017 at 16:40.
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Old 2nd Aug 2017, 20:13
  #530 (permalink)  
 
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NTSB Issues Investigative Update on San Francisco Airport Near Miss

Summary of new / confirmed details:
  • The National Transportation Safety Board (NTSB) was notified of the incident on Sunday, July 9 [two days after the incident]
  • The NTSB investigator-in-charge has formed the following groups: Air Traffic Control (ATC), Operational Factors, Human Performance, Airports, and Flight Data Recorders (FDR)
  • The incident airplane’s cockpit voice recorder had been overwritten, so NTSB investigators did not have that data.
  • The captain was the pilot flying ACA759, and the first officer was the pilot monitoring. Both pilots held Canadian airline transport pilot certificates.
  • The captain had over 20,000 total flight hours, of which about 4,797 hours were as captain in Airbus A320‑series airplanes. The first officer had about 10,000 total flight hours, of which over 2,300 hours were in Airbus A320-series airplanes.
  • At 2349 PDT (7 minutes before the incident), all positions in the ATC tower (controller-in-charge local control, local control assist, ground control, flight data, and clearance delivery) were combined at the local control position.
  • As ACA759 approached SFO, at 2355:52 PDT, the airplane flew too far right of course to be observed by the local controller’s ASDE-X/ASSC and was not visible on the ASDE-X/ASSC display for about 12 seconds.
  • At 2355:56 PDT, when ACA759 was about 0.3 mile from the landing threshold, the local controller confirmed and recleared ACA759 to land on runway 28R.
  • The flight crew of the first airplane in queue on taxiway C (UAL1) transmitted statements regarding ACA759, one of which mentioned the alignment of ACA759 with the taxiway while ACA759 was on short final (see figures 2 and 3). The flight crew of the second airplane in queue on taxiway C switched on their airplane’s landing lights as the incident airplane approached.
  • The incident pilots advanced the thrust levers when the airplane was about 85 ft agl. FDR data indicate that the airplane was over the taxiway at this time, approaching the vicinity of taxiway W.
  • At 2356:04 PDT, ACA759 reappeared on the local controller’s ASDE-X/ASSC display as it passed over the first airplane positioned on taxiway C.
  • About 2.5 seconds after advancing the thrust levers, the minimum altitude recorded on the FDR was 59 ft agl.
  • At 2356:10 PDT, the local controller directed ACA759 to go around. The airplane had already begun to climb at this point
  • In postincident interviews, both incident pilots stated that, during their first approach, they believed the lighted runway on their left was 28L and that they were lined up for 28R. They also stated that they did not recall seeing aircraft on taxiway C but that something did not look right to them.


NTSB narrative: Figure 3 shows UAL1’s transmission at 2356:04 and ACA759’s position as it overflies the first airplane waiting on the taxiway; note that the second airplane has turned on its landing lights.

Links:
https://www.ntsb.gov/news/press-rele...r20170802.aspx
https://ntsb.gov/investigations/Pages/DCA17IA148.aspx
NTSB finds 'blind spot' in SFO radar after Air Canada event
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Old 2nd Aug 2017, 21:50
  #531 (permalink)  
 
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As ACA759 approached SFO, at 2355:52 PDT, the airplane flew too far right of course to be observed by the local controller’s ASDE-X/ASSC and was not visible on the ASDE-X/ASSC display for about 12 seconds.
As stated before, they could have been trying to land on 28L and the system would not have known, or it appears alerts to the issue.

[/I]The incident pilots advanced the thrust levers when the airplane was about 85 ft agl. FDR data indicate that the airplane was over the taxiway at this time, approaching the vicinity of taxiway W.[/I]
What time were the levers advanced?

[/I]At 2356:04 PDT, ACA759 reappeared on the local controller’s ASDE-X/ASSC display as it passed over the first airplane positioned on taxiway C.[/I]
Because now you have an aircraft on the taxiway so the system finds it?!?!?

[/I]About 2.5 seconds after advancing the thrust levers, the minimum altitude recorded on the FDR was 59 ft agl.[/I]
Again, a time is missing... 26 feet momentary descent! PAL was an A343 with a tail height of 56 feet...

3 feet from disaster?

So much for the afterglow...

Last edited by underfire; 2nd Aug 2017 at 22:12.
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Old 2nd Aug 2017, 22:10
  #532 (permalink)  
 
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CVR lost.

The CVR is overwritten and the crew can not recall overflying 4 aircraft!
WOW!
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Old 2nd Aug 2017, 22:13
  #533 (permalink)  
 
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Originally Posted by underfire View Post
Ian, how can you say that the problem has been solved, when you also say that it was not necessary to include provisions for tracking the ac to prevent landing on the taxiway? The information provided by the FAA's Surface Movement Event Service showed the ac was lined up with the taxiway, along with the altitudes, yet this system provided no alert, nor did the systems it feeds data to, ASDEX or in this case, ASSC? How can one provide runway conflict warning when incoming ac are not tracked?

Care to guess who provides these systems? (and the one at SFO?)
U.S. Federal Aviation Administration selects Saab Sensis for Airport Surface Surveillance Capability Program

The Saab/Sensis system does not appear to have provisions for tracking which runway or taxiway the ac is landing, and alert/prevent. As far as I can tell, the Sensis system is really for ground ops, not a combination. How can one provide runway conflict warning when incoming ac are not tracked?


The system at SFO was supposed to be tracking inbound ac to 5nm with option for 20nm, yet it failed to alert the controller. For all we know, the ac could have been lined up on 28L instead of the taxi, what is, or even, is there an alert algorithm?

It was the prototype, and is supposed to be deployed at other airports in the US. Again, it is good that we had a lowest common denominator (airline with history of landing on taxiways) test of the system so that it is fixed and not deployed throughout the network.

It is interesting because NAVCANADA has an ATM ground track management system for tower ops that does track inbound aircraft when the threshold is obscured from tower.
The problem - tracking aircraft, on the ground and close in on approach to identify which runway (taxiway) they were lined up for etc., has been solved it can be done and it has been demonstrated several times with live aircraft on a live airport. Nevertheless, the people who decide what goes operational thought that this was not a problem that needed a solution - even though it would have been ideal for so called virtual control towers. A version without some sensors and with different plan view displays rather than 3D virtual reality was what went ahead. So technically solutions are available and probably significantly cheaper than the cost of a crash into a line of widebodies - the problem is with bean counting. You persuade the beancounters and the system could be rolled out.
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Old 2nd Aug 2017, 22:43
  #534 (permalink)  
 
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How is it that only UAL 1 said anything? There's some fair distance between them and the PAL A340 ... surely they too must have noticed something amiss? I mean a massive jet heading directly at you is not what you expect waiting on a taxiway!
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Old 2nd Aug 2017, 23:26
  #535 (permalink)  
 
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Do we know if CVR recovery is possible? Or being attempted?
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Old 2nd Aug 2017, 23:30
  #536 (permalink)  
 
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Originally Posted by peekay4 View Post
At 2356:10 PDT, the local controller directed ACA759 to go around. The airplane had already begun to climb at this point
At least that finally settles the debate about which came first: the crew's decision to go around or the controller's instruction to do so.
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Old 3rd Aug 2017, 01:08
  #537 (permalink)  
 
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@ DaveReidUK...

Does it matter if the pilots applied power for the go around first or that the tower told them to go around afterwards?

In the grand scheme of things it doesn't really matter because they were going to land on Taxiway C if it wasn't for the actions of UAL 1's and PAL 115...

To me this statement is the most important clue as to why a major accident was avoided...

"The flight crew of the first airplane in queue on taxiway C (UAL1) transmitted statements regarding ACA759, one of which mentioned the alignment of ACA759 with the taxiway while ACA759 was on short final (see figures 2 and 3). The flight crew of the second airplane in queue (PAL 115) on taxiway C switched on their airplane’s landing lights as the incident airplane approached."

Without the actions of both these aircrafts, especially PAL 115's landing lights being turned on, it's almost 100% sure that AC759 would have landed on Taxiway C and collided with PAL 115 and perhaps the other 2 aircrafts following it on the taxiway.

The experience level of both pilots is high enough to conclude inexperience is not a factor... I would really like to know what was the major factor that created this incident in the first place... Unbelievable.
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Old 3rd Aug 2017, 01:40
  #538 (permalink)  
 
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Originally Posted by Smott999 View Post
Do we know if CVR recovery is possible? Or being attempted?
CVRs are intended for accident investigation, usually when there is a hull loss.

In this case, the crew is alive and well and probably subject to "endless" interrogation. And, the FDR is obviously intact. And, all the data from many points on the airport are intact.

The UAL captain was undoubtedly interviewed.
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Old 3rd Aug 2017, 02:23
  #539 (permalink)  
 
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Originally Posted by DDMow View Post
It's possible that English Language Fluency played a role that night at SFO. The AC759 crew were fully fluent in english, and as such were able to both understand and act immediately to UA01's radio transmission. What if the crew had not been fluent in english? What if this had been a foreign (no disrespect, simply a fact considering the numbers of asian airliners flying into SFO) airliner flown by foreign pilots that were NOT FLUENT IN ENGLISH? Keeping all other approach factors the same as AC759's were that night, the delay in understanding, by even a few seconds, the importance of what UA01 had said over the radio and acting on the information might very well have resulted in a Tenerifesque collision.
Personally I believe the UAL 1 call to tower was perhaps at best a first wake up call to the AC crew but they still continued in their landing phase past UAL 1 because go around trust was only applies at 85 feet AGL (past UAL 1).

What I believe saved the day was PAL 115 turning on their landing lights. They must have been scared sh!less at the approaching aircraft!
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Old 3rd Aug 2017, 02:24
  #540 (permalink)  
 
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Originally Posted by aterpster View Post
CVRs are intended for accident investigation, usually when there is a hull loss.

In this case, the crew is alive and well and probably subject to "endless" interrogation. And, the FDR is obviously intact. And, all the data from many points on the airport are intact.

The UAL captain was undoubtedly interviewed.
I'm sure they interviewed the PAL 115 crew too... They had the best view in the house!
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