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teachpdx
Topic Author
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AA6092 20JUL - TCAS maneuver - how common?

Fri Jul 22, 2022 5:07 pm

I had a friend aboard AA6092 LEX-CLT on July 20. The flight diverted to AVL due to weather in CLT, and TCAS was activated during approach to AVL.

Looking at FR24 data the flight was on the crosswind nearly directly south of active runway 17 at around 9000’ when it sharply climbs to 10000’ and turns left.

Apparently it was quite the ride onboard.

On LiveATC: “Piedmont 6092 responding to an RA”.
Then given vectors “20 degrees left for traffic”.
Later on: “We didn’t see ‘‘em but we got a climb RA.”

Listening to LiveATC it appears that an Endeavor flight was too high on approach and went missed and was given vectors to rejoin the pattern. It was likely this flight that triggered TCAS for AA6092.

Interestingly, this doesn’t appear to match what was told to the passengers in the cabin. They were apparently told that an “amateur aircraft” that was not in contact with ATC was spotted out the window and the pilots had to evade visually. It made a lot of people on board feel like they had just had a near-death experience, tears were flowing, the whole bit.

So a couple of questions, mostly for the pilots out there:

How common is TCAS (RA) activation in normal operations?

And why does it seem that the crew chose to embellish the situation to the passengers, making it sound more serious than it was? You’d think that they would try to downplay the situation. How common is it to sensationalize things over the PA?
 
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Starlionblue
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Re: AA6092 20JUL - TCAS maneuver - how common?

Sat Jul 23, 2022 7:13 am

They're not uncommon. So common, in fact, that the A350 has auto-TCAS as standard and the A330 as an option. The A350 even has auto-TCAS during an automated emergency descent.

As for how many events a year, I don't really know. I've seen TAs but not an RA yet. One more reason to watch your climb/descent rate if there is traffic around.
 
e38
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Re: AA6092 20JUL - TCAS maneuver - how common?

Mon Jul 25, 2022 12:22 am

teachpdx wrote:

How common is TCAS (RA) activation in normal operations?

And why does it seem that the crew chose to embellish the situation to the passengers, making it sound more serious than it was? You’d think that they would try to downplay the situation. How common is it to sensationalize things over the PA?


At my company, practicing the TCAS RA maneuver is part of the curriculum in both initial and recurrent training. The emphasis is on reacting quickly, but executing the maneuver in a smooth, controlled manner. However, as a simulator instructor, I have seen quite a few pilots react aggressively with very abrupt control inputs. Invariably, that results in repeating the maneuver.

In the past few years, I have executed the TCAS RA a couple of times. Both times were on final approach in VMC conditions, using the ILS as a backup and still outside the final approach fix. Other than filing the appropriate reports, I would have to say they were generally "non-events." In one case we were able to gently maneuver the aircraft back onto a normal glidepath and continue the approach to landing. In the other situation, we simply climbed as directed by the RA, reported the incident to ATC, and were vectored back around to another approach.

Re:, your question, "How common is it to sensationalize things over the PA?"

Not common. You want to keep information brief and factual, without sensationalism.

It seems the flight in your example was operated by one of American's commuter affiliates--Piedmont. Although it is difficult to recreate the exact situation the crew faced with the traffic conflict, it is possible you have an experience issue both with the crew executing the procedure and in speaking to the passengers.

Some pilots are just not good communicators.

e38
 
CosmicCruiser
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Re: AA6092 20JUL - TCAS maneuver - how common?

Tue Jul 26, 2022 12:49 pm

Starlionblue wrote:
They're not uncommon. So common, in fact, that the A350 has auto-TCAS as standard and the A330 as an option. The A350 even has auto-TCAS during an automated emergency descent.

As for how many events a year, I don't really know. I've seen TAs but not an RA yet. One more reason to watch your climb/descent rate if there is traffic around.

I agree Starlionblue. I saw a few TAs and only 1 RA in the EWR area.
 
Woodreau
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Re: AA6092 20JUL - TCAS maneuver - how common?

Tue Jul 26, 2022 1:12 pm

The two transponders talk to each other to coordinate the RA. This becomes a problem at airports like DEN where some airlines turn their transponders to TA only. When the two planes get vectors to final, one transponder tells the other transponder it’s not going to move because it’s TA only so the other transponder commands a RA to resolve the conflict because it in TA/RA.

When both transponders are set to TA and not TA/RA then no RAs result.
 
Longhornmaniac
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Re: AA6092 20JUL - TCAS maneuver - how common?

Tue Jul 26, 2022 11:57 pm

I've had 3 RAs in my 3.5 years flying the line. They were all non-events. Almost always brought on by excessive vertical closure rate for aircraft that are properly vertically separated (of course, the planes don't know that).

Woodreau wrote:
The two transponders talk to each other to coordinate the RA. This becomes a problem at airports like DEN where some airlines turn their transponders to TA only. When the two planes get vectors to final, one transponder tells the other transponder it’s not going to move because it’s TA only so the other transponder commands a RA to resolve the conflict because it in TA/RA.

When both transponders are set to TA and not TA/RA then no RAs result.


Yep. I haven't been to Denver lately, but we had in our 10-7 pages that we could use TA only, but only during day VMC for 17L/R when they were running simultaneous ops.
 
BoeingGuy
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Re: AA6092 20JUL - TCAS maneuver - how common?

Wed Jul 27, 2022 6:27 am

Woodreau wrote:
The two transponders talk to each other to coordinate the RA. This becomes a problem at airports like DEN where some airlines turn their transponders to TA only. When the two planes get vectors to final, one transponder tells the other transponder it’s not going to move because it’s TA only so the other transponder commands a RA to resolve the conflict because it in TA/RA.

When both transponders are set to TA and not TA/RA then no RAs result.


Actually one airplane’s Transponder talks to the other airplane’s TCAS computer. And vice versa. The two Transponders don’t talk.

One airplane’s TCAS computer interrogates the other airplane’s Transponder and vice versa. When TCAS does a coordinated RA, both TCAS computers talk to each other.

The Transponders are on or in standby. It’s the TCAS computers that are in Standby, TA ONLY, or TA/RA.
 
Woodreau
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Re: AA6092 20JUL - TCAS maneuver - how common?

Wed Jul 27, 2022 11:39 am

Thank you for the clarification.
 
IAHFLYR
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Re: AA6092 20JUL - TCAS maneuver - how common?

Wed Jul 27, 2022 12:55 pm

BoeingGuy wrote:
The Transponders are on or in standby. It’s the TCAS computers that are in Standby, TA ONLY, or TA/RA.


That cannot be correct as if the transponders in on standby there is no way for ATC to track the airplane other than a raw RADAR return which does not allow for the call sign, ground speed, nor altitude to be depicted on the controllers display.
 
BoeingGuy
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Re: AA6092 20JUL - TCAS maneuver - how common?

Wed Jul 27, 2022 4:54 pm

IAHFLYR wrote:
BoeingGuy wrote:
The Transponders are on or in standby. It’s the TCAS computers that are in Standby, TA ONLY, or TA/RA.


That cannot be correct as if the transponders in on standby there is no way for ATC to track the airplane other than a raw RADAR return which does not allow for the call sign, ground speed, nor altitude to be depicted on the controllers display.


Is is correct. My comment had nothing to do with ATC tracking an airplane. I was describing possible states of the system.
 
IAHFLYR
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Re: AA6092 20JUL - TCAS maneuver - how common?

Wed Jul 27, 2022 5:16 pm

BoeingGuy wrote:
Is is correct. My comment had nothing to do with ATC tracking an airplane. I was describing possible states of the system.


Okay however, when you put down "the transponders are on or in standby" that is what my comment was based upon.
 
kalvado
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Re: AA6092 20JUL - TCAS maneuver - how common?

Wed Jul 27, 2022 7:24 pm

IAHFLYR wrote:
BoeingGuy wrote:
Is is correct. My comment had nothing to do with ATC tracking an airplane. I was describing possible states of the system.


Okay however, when you put down "the transponders are on or in standby" that is what my comment was based upon.

TCAS standby mode:
Stand-by: Power is applied to the TCAS Processor and the Mode S transponder, but TCAS does not issue any interrogations and the transponder will reply to only discrete interrogations. The transponder still transmits squitters.

Source: https://www.faa.gov/documentlibrary/med ... ooklet.pdf

There is another relevant mode:
Transponder (mode): The Mode S transponder is fully operational and will reply to all appropriate ground and TCAS interrogations. TCAS remains in Stand-by

Possibly relevant:
If the Mode S transponder fails, the TCAS Performance Monitor will detect this failure and automatically place TCAS into Standby.

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