TCAS response on SFO-bound UA 757-200 caused "serious" injury

[flashcrash]

No mention of a second/conflicting aircraft.

Two Passengers Injured During United Airlines TCAS Response - AVSN

[Evan]

It's Boeing fault. Studies show that MOST TCAS RA's are not flown properly. That isn't going to change. Newer Airbus planes use an (overrideable) TCAS autopilot mode to avoid weak or overly aggressive pilot manual responses. The pilots can still take manual control with FD guidance, but a study showed that 91% of pilots left the autopilot in control. I'm not aware of any similar Boeing initiatives.

A fairly common cause of RA's at cruise stems from the limitations of the TCAS predictive logic. If an ascending plane is climbing to a safe level-off altitude below an aircraft in level cruise on the same airway, the logic cannot predict the level-off and thus an RA is triggered. Once again, Airbus has contended with this by using a TCAP function that alters the ALT* profile to lower the vertical speed as the aircraft nears the level off altitude, enough to avoid triggering an RA. Of course, this can also be done manually on any aircraft, but it is not often done.

[YSSYplanespotter]

I would argue that it's a flight training issue instead. Aggressive inputs during a TCAS RA event sound like the startle effect is in full swing there. Perhaps it's how pilots interpret RA warnings and what they mean, leading to a seemingly panicked response from those flying. None of this is new really, however it's evident that there should be more focus on training relating to these kinds of events, as well as the startle effect, in my opinion. Perhaps airlines should do surprise TCAS RA events during simulator lessons without the pilots being told beforehand into their programs. Perhaps it won't change but hopefully the number of RAs being flown properly would increase?

[Evan]

I would argue that it's a flight training issue instead. Aggressive inputs during a TCAS RA event sound like the startle effect is in full swing there. Perhaps it's how pilots interpret RA warnings and what they mean, leading to a seemingly panicked response from those flying. None of this is new really, however it's evident that there should be more focus on training relating to these kinds of events, as well as the startle effect, in my opinion. Perhaps airlines should do surprise TCAS RA events during simulator lessons without the pilots being told beforehand into their programs. Perhaps it won't change but hopefully the number of RAs being flown properly would increase?

Startle effect and time-compression create errors that are hard to train away, human nature being what it is. A sudden RA (usually these will be preceded by a traffic advisory) and the idea of an imminent mid-air collision tend to rattle one's composure. In the study I saw, about 58.7% of these were flown correctly in manual flight. Clearly, autopilot is a better approach, particularly in RVSM airspace where autoflight is otherwise required. One of the common drawback's cited with autoflight is that it breeds complacency, but I would bet my last nickle that no pilot who would respond to an RA manually would respond to an RA on autopilot with complacency. The plane flies the maneuver; the pilots monitor the automation very closely, ready to take over (but never having to).

BTW: the idea that this is 'Boeing's fault' is sort of an ongoing joke around here. I don't actually think this is Boeing's fault, but I do wish Boeing would catch up with Airbus on the technology.

[bstolle]

I would argue that it's a flight training issue instead. Aggressive inputs during a TCAS RA event sound like the startle effect is in full swing there. Perhaps it's how pilots interpret RA warnings and what they mean, leading to a seemingly panicked response from those flying. None of this is new really, however it's evident that there should be more focus on training relating to these kinds of events, as well as the startle effect, in my opinion. Perhaps airlines should do surprise TCAS RA events during simulator lessons without the pilots being told beforehand into their programs. Perhaps it won't change but hopefully the number of RAs being flown properly would increase?

I haven't checked if there are any youtube TCAS RA videos, but I have no idea why there should be a startle effect. There's almost always a TCAS TA first, so you are prepared for the RA.
Don't know if the procedures have changed in the meantime, but back in my time RA = AP OFF.

Training: You never know when a TCAS event occurs during the sim session. As written above, it's a non-event. Not much to talk about or train.

Concerning level off. Another Evan nonsense. It's of course procedure to manually reduce the ROC within the last 1000ft to avoid a TCAS RA.
That said, at normal crz levels, the available ROC isn't enough to trigger a RA anyway.

The green arc on the VSI is pretty narrow during a TCAS resolution, There's no way anyone would aggressively pitch up/dn if he wants to stay within the green arc.
Even if the RA turns into a climb/descend NOW, the required pitch change isn't that big, especially not at cruise alt & speed.

[Evan]

Concerning level off. Another Evan nonsense. It's of course procedure to manually reduce the ROC within the last 1000ft to avoid a TCAS RA.
That said, at normal crz levels, the available ROC isn't enough to trigger a RA anyway.

Haha yes, where do I come up with all my "nonsense"...

Oh, now I remember...

Flight crews reacted correctly to a TCAS Resolution Advisory (RA) in only 58.7% of cases according to a recent study published by Eurocontrol(*) in April 2021. In 29.8% of cases, the flight crew reacted by modifying the aircraft trajectory but did not reach the expected target. In 11.5% of cases, the flight crew did not react, or they reacted excessively and sometimes had the opposite reaction to what the RA requested.

“Level off” RAs made up 65% of all observed RAs in the Eurocontrol Study.

(*)“The assessment of pilot compliance with TCAS RAs, TCAS mode selection and serviceability using ATC radar data” issue 2.1 published on 09/04/2021 by Eurocontrol.

The Airbus TCAS mode can be flown with AP or FD guidance. Almost all pilots in an Airbus study chose to keep the AP on.

If the flight crew prefers to follow the RA using the standard TCAS warning procedure, they can revert to it at any time. However, an Airbus analysis of more than 130 000 flights performed by A350 and A380 aircraft confirms the confidence of flight crews in the AP/FD TCAS function: in 91% of the RA situations, the flight crew kept the autopilot ON.

[bstolle]

Haha yes, where do I come up with all my "nonsense"...

That's what I'm always asking myself. In case others are wondering why I'm not replying to your nonsense, this is a classic example and I'm making an exception.

If you would compare the number of level offs with the number of level offs triggering an RA, you would realize that 99.9% or even 99.99% of level offs are correctly done according to procedure.
You provided zero numbers for actual level offs, so the fact that 65% of the RAs or due to a too high/low climb rate, doesn't mean anything.
You are again drawing wrong conclusion...as usual.
If you would be even remotely correct, we would have a lot more level off RAs every day.

[Evan]

That's what I'm always asking myself. In case others are wondering why I'm not replying to your nonsense, this is a classic example and I'm making an exception.

If you would compare the number of level offs with the number of level offs triggering an RA, you would realize that 99.9% or even 99.99% of level offs are correctly done according to procedure.
You provided zero numbers for actual level offs, so the fact that 65% of the RAs or due to a too high/low climb rate, doesn't mean anything.
You are again drawing wrong conclusion...as usual.
If you would be even remotely correct, we would have a lot more level off RAs every day.

I said that “a fairly common cause of RA’s” are level-offs. You called that nonsense. I just schooled you otherwise. Admit it.

I said nothing about RA’s being common during level offs. Admit that too.

And maybe do your research before you denigrate others on this forum. Believe it or not, there are things you don’t learn it the cockpit.

[bstolle]

I said that “a fairly common cause of RA’s” are level-offs. You called that nonsense. I just schooled you otherwise. Admit it.

Your stupidity is truly amazing.
You wrote ..... the aircraft nears the level off altitude, enough to avoid triggering an RA. Of course, this can also be done manually on any aircraft, but it is not often done.

And that's what I replied to. I not going to to waste my time replying to you ever again, that's for sure.
Denigrate you? Sorry, but that's impossible. ROFL.

[Evan]

Yesterday the airline reported that the UAL 757 was descending toward another aircraft when the RA occurred.

[Evan]

Your stupidity is truly amazing.
You wrote ..... the aircraft nears the level off altitude, enough to avoid triggering an RA. Of course, this can also be done manually on any aircraft, but it is not often done.

And that's what I replied to. I not going to to waste my time replying to you ever again, that's for sure.
Denigrate you? Sorry, but that's impossible. ROFL.

Feel free to be amazed and not reply but these are the facts:

ICAO ( PANS-OPS Doc. 8168 )recommend to adopt a vertical speed below 1500ft/min throughout the last 1000ft of climb or descent to the assigned altitude [the FAA recommends 500-1000ft/min]. As a matter of fact, these recommendations are rarely applied. Several airlines do not have them incorporated in their operational recommendations. Even when they are, some pilots confess they are not always applied. As a result there is still a significant number of undesired RAs observed during 1000ft level-off manoeuvres.

The autopilot issue was significant enough to prompt Airbus to alter their ALT* altitude capture law to ALT*TCAP, which they claim has the operational benefit of avoiding more than 95% of all previous Level-Off RA's.

We don't have the facts on this incident yet, but based on the statistics, it is probable that it was caused by an excessive vertical convergence rate before a level off.

[ATLcrew]

I said that “a fairly common cause of RA’s” are level-offs.

I said nothing about RA’s being common during level offs

Well...where I come from that's called getting off on a technicality (even then only barely). I wonder, Evan, if perhaps there might be an AD that would rectify this. And/or perhaps a TCAS guarded switch somewhere. In fact, I seem to recall BoeingBobby telling us about how he once got an RA off a Twin Otter when he was taking his 747 (on which he has 68,314 hours) into Lukla (he landed on Rwy 24, too). He leveled off manually, so all was well.

[Evan]

Well...where I come from that's called getting off on a technicality (even then only barely). I wonder, Evan, if perhaps there might be an AD that would rectify this. And/or perhaps a TCAS guarded switch somewhere. In fact, I seem to recall BoeingBobby telling us about how he once got an RA off a Twin Otter when he was taking his 747 (on which he has 68,314 hours) into Lukla (he landed on Rwy 24, too). He leveled off manually, so all was well.

The usual vitriol aside, how is that 'getting off on a technicality?"
I didn't say anything of the sort. If RA's were common during all level-offs, we would have hundreds of them daily. Is that what I said?

Level-off RA's require an excessive vertical speed in the final 1000-2000ft before level-off AND another airplane in TCAS proximity on a conflicting flightpath at that moment. Does that scenario happen with every level-off?

What I said was that level-offs were a common cause of RA's, and that ICAO and FAA recommendations for level-off technique to avoid RA's are not often followed (their words: 'rarely followed').
Actually, Airbus and Eurocontrol made that determination through hard research. I'm just stating are facts as they have reported them.
But perhaps you feel that you know better than them. That wouldn't surprise me.

Another 'nothing to see here' attitude towards a real problem, one that the industry takes quite seriously,

[3WE]

Doesn’t everyone have a good, real-time traffic depiction so that a black acronym-box should not_be screaming “oh shit”…that pilots should recognize convergence nice and early and understand how it will be resolved and if they need to think about doing their own thing?

I agree with ATL, we need a guarded switch!

[ATLcrew]

What I said was that level-offs were a common cause of RA's, and that ICAO and FAA recommendations for level-off technique to avoid RA's are not often followed (their words: 'rarely followed').
Actually, Airbus and Eurocontrol made that determination through hard research. I'm just stating are facts as they have reported them.
But perhaps you feel that you know better than them. That wouldn't surprise me.

ONE article in Airbus Safety First and ONE Eurocontrol study is "Hard Research"? But perhaps you feel any research that fits your narrative of the week is "hard research". That wouldn't surprise me.