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Author Topic: Near Miss @ KSFO - We Need to Talk!  (Read 21941 times)
ect76
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« on: March 30, 2010, 08:04:39 PM »

In case anyone here hasn't read/heard on AVHerald...

Incident: United Airlines B772 at San Francisco on Mar 27th 2010, near collision


"A United Airlines Boeing 777-200, registration N216UA performing flight UA-889 from San Francisco,CA (USA) to Beijing (China) with 251 passengers and 17 crew, was departing San Francisco's runway 28L and was cleared to climb to 3000 feet. When the Boeing had just retracteed gear and was climbing through 1100 feet, the tower reported traffic at the one o'clock position. Immediately thereafter the Traffic and Collision Avoidance System issued a Traffic Advisory "Traffic! Traffic!". The crew spotted a light high wing aircraft, an Aeronca registration N9270E, in a hard left turn changing from their one to three o'clock position, the first officer being pilot flying pushing the control column forward to level the Boeing. Both crew members of the Boeing only saw the underside of the Aeronca, that passed the Boeing at a distance of 200-300 feet, while the TCAS now prompted a Resolution Advisory "Descend! Descend!" After being clear of conflict the Boeing continued to Beijing for a safe landing.

The NTSB reported they have launched an investigation into the near collision to determine, how the airplanes could get as close as an estimated 300 feet to each other. A NTSB investigator has been dispatched to San Francisco to begin the investigation."


Audio clip attached, credit to AVHerald for the audio edit. Sounds like it was pretty close.

* ua889_near_collision_sfo_100327.mp3 (352.86 KB - downloaded 4638 times.)
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rtav
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« Reply #1 on: March 30, 2010, 08:57:18 PM »

Just read about it in the news and then came here to check for a clip - thanks for posting.
Can't imagine how the Aeronca ended up off the departure end at that altitude?  Any ideas??
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egon
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« Reply #2 on: March 30, 2010, 09:38:48 PM »

That would be a pretty standard altitude for a general aviation aircraft around that area.  The tower controller identified it as a Cessna, at 1500.  The directions are often "at or below 1500".
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mstram
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« Reply #3 on: April 03, 2010, 07:55:49 AM »

It sounds like the controller says :

"70Echo maintain (zero ?) separation path behind that aircraft"

"Zero separation path" ?  .. is that what he said?

If so, what is a "zero separation path" ? ... never heard that term before

Mike
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KHAOS
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« Reply #4 on: April 03, 2010, 08:09:33 AM »

It sounds like the controller says :

"70Echo maintain (zero ?) separation path behind that aircraft"

"Zero separation path" ?  .. is that what he said?

If so, what is a "zero separation path" ? ... never heard that term before

Mike
The term "zero separation path" doesn't exist in standard phraseology.

Hope this is a little clearer:

Quote
"Seven zero echo, traffic off the departure end, climbing out of 500, heavy triple-7."

"Seven zero echo <unintelligible> in sight."

"Seven zero echo, maintain visual separation, pass behind that aircraft."

"Seven zero echo, pass behind him."

"...just ahead and to your right, has you in sight, Cessna, one-thousand five-hundred, they're maintaining visual separation."

"<United> 889 heavy, traffic no factor, contact NorCal departure."

"Ok that set off a TCAS, that was...we need to talk."

"Roger."


« Last Edit: April 03, 2010, 07:11:30 PM by KHAOS » Logged
mstram
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« Reply #5 on: April 03, 2010, 08:59:24 AM »


The term "zero separation path" doesn't exist in standard phraseology.

"Seven zero echo, maintain visual separation, pass behind that aircraft."


Well "visual" makes more sense, but I listened to it a bunch of times, if that's what he said, it sure wasn't clear .. to me .. anyway on that recording.
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KHAOS
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« Reply #6 on: April 03, 2010, 07:10:08 PM »

I totally agree with you on that, it really does sound like "zero." 

When he tries to say "visual", the mike probably didn't pick up the first part of the word, or he said it too quiet.  So all you hear is "-sual."
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atcman23
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« Reply #7 on: April 04, 2010, 08:38:20 AM »

This sounds like the procedure is right out of the book.  The Cessna pilot stated that he had the B777 in sight and was instructed to maintain visual and then the controller advised the B777 of the Cessna and that they were maintaining visual.  Since they are using visual separation, there is no minima requirement (just don't hit the other aircraft).  I think the Cessna pilot may have done something incorrectly combined with the B777 crew overreacting to the TCAS advisory.  If the controller is blamed for this, it would change the way tower controllers do their job completely.  No fault of the controller from what I see, just a pilot making a bad decision followed by another pilot overreacting to something that is minor.
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Mark Spencer
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« Reply #8 on: April 05, 2010, 02:28:59 PM »

How did you determine that the B777 pilot overreacted to TCAS?
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ect76
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« Reply #9 on: April 05, 2010, 03:30:42 PM »

I'm no pilot, or indeed controller, but I'd say that any incident resulting in a TCAS RA was a potentially serious one! Feel free to correct me if I'm wrong?
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atcman23
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« Reply #10 on: April 05, 2010, 08:06:16 PM »

They were advised of the Cessna and that they were maintaining visual separation from the B777.  Instead of going, "holy crap TCAS!" maybe they'd better look out the window real quick to see if it may be an issue.  The TCAS sensitivity is usually turned down in the terminal environment otherwise it would always go off.  Again, the Cessna likely got too close (we don't know how close of course) and yes if I were the pilot I might be a little irked but not enough to go "we need to talk!" on the frequency (ASRS was created for a reason).  IMO, the controller followed the rules by the book and you can tell that he has done it before.  The Cessna just did something they probably shouldn't have but again, visual separation has no criteria expect that the aircraft don't hit.  From the sounds of it, the TCAS sounded but no resolution was issued (i.e. climb/descend).  That could be inaccurate but the crew did not respond to the controller stating "United XXX TCAS climb/descend" (which is ICAO standard I believe); they just stated that the aircraft set off the TCAS.  So yeah, I think the pilot overreacted to the TCAS by getting on the radio demanding to "talk" to the controller right now when in fact flying the aircraft was priority #1, not talking about how to apply visual separation.
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Mark Spencer
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« Reply #11 on: April 05, 2010, 09:25:02 PM »

I'm no pilot, or indeed controller, but I'd say that any incident resulting in a TCAS RA was a potentially serious one! Feel free to correct me if I'm wrong?

Not quite every incident. There are times were a pilots get a TCAS RA based on another aircraft's climb/decent rate even though they are still several thousand feet apart and/or on diverging courses. Also there are things other then planes with transponders, namely ships. I've had plane's ask about info on traffic when it was just a ship sitting in a harbor.
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ect76
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« Reply #12 on: April 06, 2010, 05:48:44 AM »

Fair enough then - That's why I added the disclaimer about not being a controller or pilot  grin
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djmodifyd
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« Reply #13 on: April 06, 2010, 10:48:27 PM »

They were advised of the Cessna and that they were maintaining visual separation from the B777.  Instead of going, "holy crap TCAS!" maybe they'd better look out the window real quick to see if it may be an issue.  The TCAS sensitivity is usually turned down in the terminal environment otherwise it would always go off.  Again, the Cessna likely got too close (we don't know how close of course) and yes if I were the pilot I might be a little irked but not enough to go "we need to talk!" on the frequency (ASRS was created for a reason).  IMO, the controller followed the rules by the book and you can tell that he has done it before.  The Cessna just did something they probably shouldn't have but again, visual separation has no criteria expect that the aircraft don't hit.  From the sounds of it, the TCAS sounded but no resolution was issued (i.e. climb/descend).  That could be inaccurate but the crew did not respond to the controller stating "United XXX TCAS climb/descend" (which is ICAO standard I believe); they just stated that the aircraft set off the TCAS.  So yeah, I think the pilot overreacted to the TCAS by getting on the radio demanding to "talk" to the controller right now when in fact flying the aircraft was priority #1, not talking about how to apply visual separation.


TCAS are turned to traffic advisories only in the terminal area....in other words they do not get RA's...because situations like this happen....im not wondering if the UAL pilot forgot the TCAS in RA mode?
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Windtee
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« Reply #14 on: April 07, 2010, 03:13:17 AM »

Interesting scenario. At the very least, all are alive. A good "see-and-avoid" reminder for us all.
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« Reply #15 on: April 21, 2011, 01:05:05 AM »

Here is an interesting article on the United 889 / Cessna 182 (N9870E) near miss incident over San Bruno, CA last year.
http://www.tourismandaviation.com/news-8294--How_Close_United_Airlines_Flight_889_Came_To_A_Midair_NTSB_Report_
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KHWD Ground/Tower
KOAK Del/Gnd/Twr
KSFO NORCAL App Rwy 28L/R
KSFO Tower/Ground
NORCAL Approach (KOAK)
NORCAL Departure (KSFO/KOAK)
KSJC NORCAL Approach #2
ZOA Oakland Center (35/40/41)


RJTT App/Dep
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alltheway
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« Reply #16 on: April 21, 2011, 06:03:27 AM »

There are two topics about this incident, would it be possible to merge these Dave?

Thanx

http://www.liveatc.net/forums/atcaviation-audio-clips/near-miss-at-ksfo-we-need-to-talk!-(woak-ctr)


The exclamation point is screwing up....
« Last Edit: April 21, 2011, 06:16:49 AM by alltheway » Logged
keith
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« Reply #17 on: April 21, 2011, 12:18:02 PM »

Background on SFO GA transitions:
GA typically remain west of hwy 101 (which runs just west of SFO itself) when transitioning the airspace. This keeps them clear the 1L/R departure stream.

When they run a heavy departure off 28L/R, they sometimes route the GA traffic over the top of the airport, then a NW heading until the 28L/R guy is clear, then back over to the west side of 101. (I've flown the transition several times, and have had both variations take place).


I would be curious what would possess the GA pilot to fly so close to the departing jet as to cause the interaction that just happened. Obviously, TCAS isn't smart enough to know that the approach/converging traffic has you in sight and will maintain vis sep. So, I'm wondering why RA's were enabled? Is it SOP to disable RA's in all terminal areas, or is it airline-specific, or crew discretion?

I'm trying to work out if the crew over reacted, or if the GA pilot flew unusually close.
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alltheway
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« Reply #18 on: April 21, 2011, 12:45:51 PM »

That now was why I asked Dave to merge the two topics, but here's what I wrote in the other topic:

I found this on the internet,

Quote:"Terminal Area (Norcal Approach)
Basic separation within 40 miles of single antenna is three miles in airport/terminal airspace. IFR/VFR separation is 1.5-miles in Class B. Beyond 40 miles of antenna it is 5 miles.

The pilot should know that under VFR conditions once you have told ATC that you have visual contact with traffic you may not receive any further radar advisories on that traffic. They may not advise you again of altitude or direction. It is up to you to evade any possible wake turbulence. ATC will let you fly right under a DC-10' wake turbulence and not issue a warning. You must be aware of this lack of protection and be assertive enough to make a 360 or whatever it takes for avoidance. It may be best not to 'see' traffic "

Got this from:
http://www.whittsflying.com/web/page5.310Bay_Area_ATC_System.htm
« Last Edit: April 22, 2011, 06:12:29 PM by alltheway » Logged
StrongDreams
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« Reply #19 on: April 21, 2011, 03:43:30 PM »

The NTSB report appears to blame ATC ("an operational error occurred at SFO ATCT").

Link to report.
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sykocus
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« Reply #20 on: April 21, 2011, 04:33:06 PM »

I don't see where the operational error was. The Cessna was told to maintain visual separation, the UAL was told the Cessna was maintaining visual separation.
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keith
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« Reply #21 on: April 22, 2011, 02:09:32 PM »

Thanks for posting the link to the NTSB report. It's really worth reading closely.

I'm still not sure what the operational error was here, the only thing that springs to mind is that minimum lateral/vertical separation of two targets in the Bravo was not maintained PRIOR to the Cessna pilot accepting visual separation.

That makes sense based on the report from UAL of seeing the Cessna "turning hard..."  In other words, the traffic point out was essentially pretty late in the game.

Reading the report, it basically implies that nobody was really paying attention to the transitioning Cessna.  I'm not easily rattled, but THAT is an issue.  The recommendations at the end of the report are actually reasonable.  They mention the possibility of a standalone freq for handling GA transitions, similar to what LGA and EWR have.  I have used the LGA/EWR VFR tower freqs, and they are awesome for several reasons.

I've also used the SFO twr freq when transitioning, and on two occasions, had to circle over Bay Meadows while awaiting a break on the frequency to get a word in.  Thankfully, they knew I was coming (coordinated by SQL tower ahead of time). Had they not known I was coming, a cold call would've tied up the frequency for a relatively long time, during which time the tower would be unable to issue takeoff/landing/LUAW instructions to the heavy metal at SFO.

A standalone position makes all the sense in the world, I think, because transitioning SFO is _not_ always straight forward (there's no Silver Bullet routing that makes sense 24/7), and the tower is already busy enough.

All of that said, the Cessna pilot should've maintained better situational awareness.  If you're southbound in the Bravo while transitioning SFO, you should have your eyes peeled on the 28's, watching for go-arounds, or departures.  How the pilot did not know (apparently), that a jet had launched from one of the 28's and was heading toward him is a bit of a mystery to me, since he was on the same frequency.

SFO is a fast-running operation with the deps on 1L/R sneaking out in between the 28L/R arrival stream. It's not hard to imagine how a relatively infrequent operation (Bravo transition by a GA aircraft) would be forgotten.

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alltheway
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« Reply #22 on: April 22, 2011, 06:39:56 PM »

 cool The Cessna should have been assertive to avoid this close call, maybe he had the text "objects in windshield appear closer than they are" in front of him...

/sarcastic mode off/

Found this about using TCAS:
http://www.skybrary.aero/index.php/Incorrect_use_of_TCAS_Traffic_Display

Where it says: "quote - ICAO Doc 8168: PANS-OPS, Chapter 3, Section 3.2 states unequivocally that "pilots shall not manoeuvre their aircraft in response to traffic advisories (TAs) only. (This) restriction in the use of TAs is due to limited bearing accuracy and to the difficulty in interpreting altitude rate from displayed traffic information."

And this : http://www.skybrary.aero/index.php/TCAS_II_Activation

Where it says : ICAO PANS-OPS Doc 8168 (and also the ACAS Manual Doc 9863)

Although the TCAS RA function is inhibited, with the system selected on, when an aircraft is on the ground - and also at low altitudes when airborne - it is very important for operational safety that the system is selected on before take off, to ensure that the RA function will be active as soon as the built-in system constraints allow this during the initial climb. It would be completely impracticable for flight crew to routinely select TCAS on (or off) whilst airborne at low altitude.
« Last Edit: April 22, 2011, 07:34:26 PM by alltheway » Logged
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