TCAS RA at Aircraft's Certified Ceiling
Lookforshooter, any aircraft fitted with ACAS – commercial or GA – will only have vertical, climb or descend type commands. There is no turning flight associated with ACAS in any aircraft type.
ACAS is designed not ‘to fly you in to trouble’, indeed it does the very opposite and provides information of how to avoid trouble.
All aircraft have essentially the same system, thus whether a large or small aircraft, commercial or GA, all pilots must follow the commands; if someone does not, then there is an accident waiting to happen.
Commercial aircraft are flown by professionals who have the required airmanship / discipline to obey ACAS.
History may identify the one dominant accident involving ACAS as a problem of worldwide communication – ensuring that all crews, operators, and national authorities work to the same set of rules. The lessons have been learnt from that accident; the international rules are now firmly established.
A remaining weakness is with those humans who do not seek the necessary knowledge to understand both the principles of the system and the rules for its operation. Yet even with these, the individual must overcome bias and mis-belief, and follow the ACAS commands.
I and probably other pilots would have concerns about your apparent weaknesses in knowledge and resultant attitude about ACAS, but the most worrying aspect is that if you don’t correct these, you might be in the same airspace as us.
Re brakes; apart from mixing up anti skid with autobrake – functionally different systems, but usually combined in the same box; you are correct about the effectiveness of manual braking. In fact any pilot can better the braking distance achievable with RTO/Max autobrake providing that s/he applies the brakes quickly and maintains maximum pressure until stopped, i.e. follows the rules.
ACAS is designed not ‘to fly you in to trouble’, indeed it does the very opposite and provides information of how to avoid trouble.
All aircraft have essentially the same system, thus whether a large or small aircraft, commercial or GA, all pilots must follow the commands; if someone does not, then there is an accident waiting to happen.
Commercial aircraft are flown by professionals who have the required airmanship / discipline to obey ACAS.
History may identify the one dominant accident involving ACAS as a problem of worldwide communication – ensuring that all crews, operators, and national authorities work to the same set of rules. The lessons have been learnt from that accident; the international rules are now firmly established.
A remaining weakness is with those humans who do not seek the necessary knowledge to understand both the principles of the system and the rules for its operation. Yet even with these, the individual must overcome bias and mis-belief, and follow the ACAS commands.
I and probably other pilots would have concerns about your apparent weaknesses in knowledge and resultant attitude about ACAS, but the most worrying aspect is that if you don’t correct these, you might be in the same airspace as us.
Re brakes; apart from mixing up anti skid with autobrake – functionally different systems, but usually combined in the same box; you are correct about the effectiveness of manual braking. In fact any pilot can better the braking distance achievable with RTO/Max autobrake providing that s/he applies the brakes quickly and maintains maximum pressure until stopped, i.e. follows the rules.
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While I understand the robotic airline flight crew approach that is taught to blindly go where the TCAS box tells them to go, I don't think most passengers will..it didn't help the pax on the mid air in Europe. As far as weakness in knowledge ....ahhh another aviation expert to to tell us how it is....your not qualified to make any judgement on aviation knowledge or experience based on a few internet posts, no one is. If you have to resort to insults in the face of a rational logical discusion...that means you can't discuss the facts presented. Insults are the refuge for the weak minded.
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"Blindly" following TCAS guidance is no different to "blindly" following windshear escape guidance, or flight director guidance in autoland, or any of a number of other cases. Yes, there may be one chance in a billion that the systems have gone u/s and are giving you misleading guidance. That's the defined certification risk, after all. But there's a great deal more than one chance in a billion that someone doing their own thing by the seat of their pants will, in fact, do the wrong thing (or a worse thing) and will create more trouble than they were in to start with.
Is the TCAS RA the optimum solution to every single encounter? No, but it's a reliable solution.
Just as in the brakes case: is the anti-skid the very best you can get? No. Maybe you can beat it by a few %. But if you try to do so, you may also screw it up and fail by more than a few %. Now, if your ALD and LFL were based on "the box", there's no upside in being a couple of hundred feet short - and a huge downside in being long, if the runway is limiting.
The entire system is set up on the assumption that the person sat in the left seat is not an expert - there's a huge community behind the procedures, some of whom are experts. Following the advice of the experts, as encompassed in SOPs, is rarely a bad idea.
Is the TCAS RA the optimum solution to every single encounter? No, but it's a reliable solution.
Just as in the brakes case: is the anti-skid the very best you can get? No. Maybe you can beat it by a few %. But if you try to do so, you may also screw it up and fail by more than a few %. Now, if your ALD and LFL were based on "the box", there's no upside in being a couple of hundred feet short - and a huge downside in being long, if the runway is limiting.
The entire system is set up on the assumption that the person sat in the left seat is not an expert - there's a huge community behind the procedures, some of whom are experts. Following the advice of the experts, as encompassed in SOPs, is rarely a bad idea.
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Mad - I don't trust my FD to tell me to turn left, but the other 5 things set up, in disparate equipment and systems to verify that I should turn left. Not to mention a sense of dead reckoning, and understanding of where I am at in the flight, what ATC is doing, and how they are equiped. I don't sit back and just hope my F/D is working. I sure hope pilots aren't just sitting back, crossing thier arms, hoping the autoland works...???!! !@!$
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Does Nascar install anti-lock brakes: No.
I'd love to know who you fly for so I can remember to stay clear.
I persevere with this thread, particularly as the issue is of great importance to all of the industry.
ACAS relies on appropriate behaviour of both parties in the event of a conflict, thus there is need for a knowledgeable, universal, well discipline approach to flight operations.
The availability of ACAS in small / GA aircraft implies that those pilots also require a similar high standard of operation (with respect to ACAS) to those in commercial operations.
Whereas a pilot of a small/GA aircraft, with poor understanding of some basic aspect or who has a macho attitude, might suffer a landing (or any other) accident, the result affects only that individual and hopefully no one else. But an inappropriate response to ACAS could result in an accident involving an unwitting third party including many passengers in a commercial aircraft.
If a GA pilot decides not to follow an RA then the commercial safety situation may be no better than it was when the need for ACAS was first noted – Cessna 172 / MD 80 collision.
I am not suggesting that all small / GA operators lack operating qualities, indeed the vast majority (as have commercial pilots before hand) have demonstrated the necessary skills, and strive to improve them before moving on to larger aircraft.
The issues are the immaturity of some people, their reluctance to learn, or poor attitudes in an operational climate where there is little or no oversight, operator / regulatory control, or a second crew member to monitor. Worst still is that a few, hopefully very few, might progress to the very light jets with opportunity to really mix with the larger aircraft.
ACAS relies on appropriate behaviour of both parties in the event of a conflict, thus there is need for a knowledgeable, universal, well discipline approach to flight operations.
The availability of ACAS in small / GA aircraft implies that those pilots also require a similar high standard of operation (with respect to ACAS) to those in commercial operations.
Whereas a pilot of a small/GA aircraft, with poor understanding of some basic aspect or who has a macho attitude, might suffer a landing (or any other) accident, the result affects only that individual and hopefully no one else. But an inappropriate response to ACAS could result in an accident involving an unwitting third party including many passengers in a commercial aircraft.
If a GA pilot decides not to follow an RA then the commercial safety situation may be no better than it was when the need for ACAS was first noted – Cessna 172 / MD 80 collision.
I am not suggesting that all small / GA operators lack operating qualities, indeed the vast majority (as have commercial pilots before hand) have demonstrated the necessary skills, and strive to improve them before moving on to larger aircraft.
The issues are the immaturity of some people, their reluctance to learn, or poor attitudes in an operational climate where there is little or no oversight, operator / regulatory control, or a second crew member to monitor. Worst still is that a few, hopefully very few, might progress to the very light jets with opportunity to really mix with the larger aircraft.
Lookforshooter
If you have TCAS II on board, you are legally obligated to follow RA commands! To not do so, puts everyone at a risk far greater than not doing so. You can have any opinion you want, but you must follow the commands, PERIOD. Yes, at this stage, only up or down plus "monitor Vertical Speed". Follow for my family's sake
SSG V1.10 lives on, to the endangerment of all, it seems.
Care to produce a few facts to back up that outrageous claim?
If you have TCAS II on board, you are legally obligated to follow RA commands! To not do so, puts everyone at a risk far greater than not doing so. You can have any opinion you want, but you must follow the commands, PERIOD. Yes, at this stage, only up or down plus "monitor Vertical Speed". Follow for my family's sake
SSG V1.10 lives on, to the endangerment of all, it seems.
Terrific..some more holier then thou pontification from the airline sector...which has caused more loss of life in aviation related incompetence then any other sector could in the next hundred years.
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Add up all the GA deaths vs Airline deaths, see who wins.
We had that little piece of statistics allready ssg, however you still spout the same nonsense. Time to wake up and leave that little cozy dreamworld of yours.
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Forum search FTW.
Go back and read the previous thread quoted by Glueball. In detail. There is too much dogma on this thread.
RAs should not be ignored. But if you think that any RA that is given to you is gaurunteed to be achieveable, you're cruising for a bruising.
Actually, that's not true.
There is an important distinction to be made between 'not following' (which is riskier, but only slightly) and 'manouvering opposite' (which is far far riskier).
This may seem like I'm laboring a point, but if you look at the really nasty TCAS incidents (including the ones that would have been collisions if there hadn't luckily been some horizontal separation) a regular feature is people manouevering opposite. Whereas there are plenty of times where RAs have not been followed and with low risk.
When pilots are told "follow the RA, always, thats all there is too it" then they are receiving incomplete guidance. The bean conters love it - a single sentence in an ops manual is cheap; proper training isn't.
It is very possible to receive an RA that is unachievable and/or otherwise unsafe. In those circumstance crew need to know what to do to minimise the risk. In my experience as a trainer if you tell people they mist follow the RA, and then give them a situation where they can't, there is a good chance they will do something really stupid unless they have a good alround knowledge of the system and other collision avoidance techniques.
To answer the Original Poster:
You follow any RA that is generated, whilst being sure to protect the aircrafts flight envelope. If the RA is a climb, and is not achievable, do your best to achieve the best rate of climb, even if its only a few hundred feet a minute, and get as close to the green arc/segment as possible.
UNDER NO CIRCUMSTANCES think "We cant get over him, we must descend!"
If you see the other aircraft, the curvature of the Earth will probably make it appear to be well above the horizon. UNDER NO CIRCUMSTANCES discard your RA in favour of your visual perception of relative altitude and commence a descent.
In other words UNDER NO CIRCUMSTANCES manoeuvre opposite the RA.
pb
Go back and read the previous thread quoted by Glueball. In detail. There is too much dogma on this thread.
RAs should not be ignored. But if you think that any RA that is given to you is gaurunteed to be achieveable, you're cruising for a bruising.
If you have TCAS II on board, you are legally obligated to follow RA commands! To not do so, puts everyone at a risk far greater than not doing so.
There is an important distinction to be made between 'not following' (which is riskier, but only slightly) and 'manouvering opposite' (which is far far riskier).
This may seem like I'm laboring a point, but if you look at the really nasty TCAS incidents (including the ones that would have been collisions if there hadn't luckily been some horizontal separation) a regular feature is people manouevering opposite. Whereas there are plenty of times where RAs have not been followed and with low risk.
When pilots are told "follow the RA, always, thats all there is too it" then they are receiving incomplete guidance. The bean conters love it - a single sentence in an ops manual is cheap; proper training isn't.
It is very possible to receive an RA that is unachievable and/or otherwise unsafe. In those circumstance crew need to know what to do to minimise the risk. In my experience as a trainer if you tell people they mist follow the RA, and then give them a situation where they can't, there is a good chance they will do something really stupid unless they have a good alround knowledge of the system and other collision avoidance techniques.
To answer the Original Poster:
You follow any RA that is generated, whilst being sure to protect the aircrafts flight envelope. If the RA is a climb, and is not achievable, do your best to achieve the best rate of climb, even if its only a few hundred feet a minute, and get as close to the green arc/segment as possible.
UNDER NO CIRCUMSTANCES think "We cant get over him, we must descend!"
If you see the other aircraft, the curvature of the Earth will probably make it appear to be well above the horizon. UNDER NO CIRCUMSTANCES discard your RA in favour of your visual perception of relative altitude and commence a descent.
In other words UNDER NO CIRCUMSTANCES manoeuvre opposite the RA.
pb
The TCAS won't descend you into a mountain, EGPWS has priority. Yes, Pitbull, if you don't follow the RA, the coordinating aircraft will have a RA of greater magnitude, but following it is the correct response. The San Diego B727/C172 crash occurred when the pilot's thought they had there traffic "in sight" when the real conflict was not in their sight. If they had a TCAS II RA, decided the plane they had in sight was not really a conflict, they would have had the mid-air. Follow the RA.The German mid-air was caused by pilots following the ATCO's instructions, rather than following the RA. This isn't brain surgery-TCAS is a "last ditch", save your butt device, not an alternative ATC device, as our friend SSG V1.10 would believe. It has saved me twice in civil aircraft and several other times in mil ops. I investigated a crew that decided they were smarter than the ATCO and the TCAS-nearly created a mid-air!!
GF
SSG: You have been shown to be in error and dangerous by any number of Ppruners that are experts in aviation, in all disciplines-pilots, engineers and operations types-a smarter man than you would retreat and try to learn, as opposed to continued idiotic posts.
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Denti...your numbers are incorrect, all I have to do is find airline crash after airline crash and find more then 49 deaths, in that ten year period.
The trend in both types of operation is very nice indeed as fatalities become less common in the last few years.
About the TCAS thing, i dont know how much training others get, but it is a normal piece of training every six months in our simulator sessions, and of course EGPWS has priority over TCAS.
The person behind Lookforshooter, is either a very misguided non pilot, or a pilot who should be identified and reported to his authority under the terms of a safety report; in either instance, s/he could be added to a Pprune ignore list.
Alternatively, granting Lookforshooter some semblance of intellect, the debate is with an individual who wishes to devil subjects with very biased views. In some circumstances there could be merit in eliciting information this way. However, there is a fine line between such arguments and the promotion of false information which the unsuspecting or unwary pilot reading Pprune might take as the truth, and thus reduce flight safety.
In this forum, this form of debate is hazardous at least, and IMHO unethical amongst such a well respected open minded group.
I do not know which of the above views is more accurate.
I still have a choice, in both what I read and what I believe; I align my understanding with the peer reviewed, expert, and majority views to help maintain a good safety record in our industry.
Alternatively, granting Lookforshooter some semblance of intellect, the debate is with an individual who wishes to devil subjects with very biased views. In some circumstances there could be merit in eliciting information this way. However, there is a fine line between such arguments and the promotion of false information which the unsuspecting or unwary pilot reading Pprune might take as the truth, and thus reduce flight safety.
In this forum, this form of debate is hazardous at least, and IMHO unethical amongst such a well respected open minded group.
I do not know which of the above views is more accurate.
I still have a choice, in both what I read and what I believe; I align my understanding with the peer reviewed, expert, and majority views to help maintain a good safety record in our industry.
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Lookforshooter
This is a seriously uneducated individual as far as TCAS/ACAS goes. Based on his input to this thread I hope he stays in Asia as I don't want to be anywhere near his accident when it eventually happens.
Moderator
After being reasonably well behaved, Lookforshooter has overstepped the mark considerably and been consigned to a gloomy place.
Protocol wise, my concern with him was not his lack of technical and procedural wisdom (that being addressed adequately by dissenting posts - indeed, such robust discussion is good for the education process of those coming up through the ranks). However the lack of civility and manners is out of line - when any poster descends into the depths of ill-considered and persistent personal attack it is sin bin time ...
Protocol wise, my concern with him was not his lack of technical and procedural wisdom (that being addressed adequately by dissenting posts - indeed, such robust discussion is good for the education process of those coming up through the ranks). However the lack of civility and manners is out of line - when any poster descends into the depths of ill-considered and persistent personal attack it is sin bin time ...
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Well I myself felt Lookforshooter made some good points! Nice to see some non airline 'SOPS only' folks in here. One thing for sure, I never saw a TCAS unit installed that talked to the ground prox, then argued with each other over who took precidence. The fact is, each unit operates independently...one worries about traffic the other about terrain. Both can and will squak, and have squaked at me in the pattern at mountainous airports at the same time. The fact is if you have a flock of airliners above you, mountains below...the PILOT will have to make a decision, not the box. Obviously there are those in here that are very uncomfortable with that.
NonFlushingLav, “… I never saw a TCAS unit installed that talked to the ground prox …”
Time to look again; commercial installations have priority logic, probably in the alerting system. In very unusual and difficult circumstances the pilot is not confronted with conflicting messages and thus does not have to make a decision.
“CS 25 AMC 25.1322 Alerting Systems
6.7 There should be only one aural signal at a time. If the possibility of two or more aural signals at the same time cannot be avoided it should be shown that each signal is clearly intelligible to the crew. The order in which the signals are presented should be that in which crew action is required.”
Re SOPs, often there is need for considered debate about SOPs, the good ones, poor ones, personal SOPs, and those which are ‘rules’. ACAS SOPs are rules with very few exceptions.
Time to look again; commercial installations have priority logic, probably in the alerting system. In very unusual and difficult circumstances the pilot is not confronted with conflicting messages and thus does not have to make a decision.
“CS 25 AMC 25.1322 Alerting Systems
6.7 There should be only one aural signal at a time. If the possibility of two or more aural signals at the same time cannot be avoided it should be shown that each signal is clearly intelligible to the crew. The order in which the signals are presented should be that in which crew action is required.”
Re SOPs, often there is need for considered debate about SOPs, the good ones, poor ones, personal SOPs, and those which are ‘rules’. ACAS SOPs are rules with very few exceptions.
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I never saw a TCAS unit installed that talked to the ground prox, then argued with each other over who took precidence. The fact is, each unit operates independently...one worries about traffic the other about terrain. Both can and will squak, and have squaked at me in the pattern at mountainous airports at the same time. The fact is if you have a flock of airliners above you, mountains below...the PILOT will have to make a decision, not the box.
With respect to the recent conversation on inhibited TCAS commands, my AOM includes the following information about certain functions:
Advisory Priority: Can revert to TA ONLY or STBY when higher priority advisories (e.g., GPWS, Windshear, etc) occur.
Altitude Climb Limit: Inhibited in accordance with aircraft performance limitations.
Descend RA: Inhibited below 1,000 feet in descent, and 1,200' in climb.
Increase Descent RA: Inhibited below 1,450'.
Resolution Advisories: Inhibited below 400' in descent and below 600' in climb. (TCAS automatically reverts to TA only)
--one might hope that with the demise of lookforshooter, the professional tone of the forum might be restored, but unfortunately he's already begun posting as nonflushinglav (strangely appropriate), and like his many other pseudonyms, has started his new posting career by agreeing with his old identity.
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Guppy that's silly...I never heard of a TCAS unit hooked up to the GPWS unit or radar altimeter. How would the TCAS unit know what altitude MSL you are? At an 8000 ft field, flying at 1400 ft in the pattern, would it know that your at 9400 ft MSL or at 1400 ft AGL?
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I've no doubt there are many things of which you haven't heard, or with which you're not familiar...seems that most things in aviation fall into that category for you. Clearly the concept of integrated avionics is among those things...things you don't understand. Once again, despite your different screen names and claims...it only goes to show who you are, and who you aren't.
Aren't the various functions integrated on your microsoft flight simulator?
Aren't the various functions integrated on your microsoft flight simulator?
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Guppy is on my ignore list...Certainly the challenge is out to everyone if they can show a TCAS unit coupled to Ground Prox and Radar Altimeters...the only way it would know not to decend you at a higher elevation altitude, into...you guessed it....mountains.