TCAS RA
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Your airline culled out all the thinkers who would have stopped after V1 if they had a fuel truck stuck under the wing...would have flown up instead of down, as what they saw outside the window is contrary to what the RA tells them to do.
So what are we talking about here...that a guy that's been culled out of thousands to take orders, unblinking, unquestioning, to robotic-ally to defer decisions aeronautical to the check list, to the captain, to the phone on the wall, NOW wants to say 'well gee maybe I can go up, instead of down?'
You chose not to make decisions and you were hired specifically not to, so this thread just jumps at me as 'well ok, now I want to be a pilot'.
So what are we talking about here...that a guy that's been culled out of thousands to take orders, unblinking, unquestioning, to robotic-ally to defer decisions aeronautical to the check list, to the captain, to the phone on the wall, NOW wants to say 'well gee maybe I can go up, instead of down?'
You chose not to make decisions and you were hired specifically not to, so this thread just jumps at me as 'well ok, now I want to be a pilot'.
Awww, you spoiled it. Already had the popcorn out, SSG is always soo much entertainment value. Nothing like a 16 year old that believes fervently in some whacko theories.
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Please I have no excuse for the crew, it was at altitude. You are crusing along, 
ATC talking in a forign language. Really? Cup of coffee in one hand and the daily news in another... Just thinking of the worst possible, I would not condem them.
ATC talking in a forign language. Really? Cup of coffee in one hand and the daily news in another... Just thinking of the worst possible, I would not condem them.
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Have I missed something here, or are you honestly saying someone managed to overstress an aeroplane following a TCAS RA?
Rat5 I agree with the posters who mentioned sim training/ briefing. If it is made clear that it is a low G manoeuvre with 5 seconds to react prior to the exercise then there is less chance of pilots over reacting. I have had a descend now RA at 3000ft in the aircraft with ATC telling us " negative maintain 3000ft" . I was an FO and PF and the Capt transmitted " negative TCAS RA" . We followed it to anout 2500ft and then after returning to 3000ft got a frequency change, the next controller asked us if it was a TA or an RA. We informed him RA. It was very simple and calm for us but I imagine if we hadn't had specific training in ignoring ATC in this situation it may have been a difficult decision to ignore them. It was actually a bit surreal as it was so much like the training we had recieved. It is also valuable to do them above FL 350 in the sim to demonstrate to the crew that the control inputs are very small and controlled.
If I may add a few points here:
EXENG: If you had waited for your RA you would never have had to fly your max rate climb. Firstly because TCAS cannot demand one, but more importantly because, once RA is activated, any manouvres are coordinated with the threat a/c. They 'talk' to each other. (and very, very quickly too!!)
This coordination is also why you should NEVER manouvre in opposition to TCAS commands, REGARDLESS of what you may 'see' out the window! To do so will likely exacerbate the avoidance manouvre required! (Or ultimately cause a collision!)
Yes you have 5 secs to respond to a TCAS RA, but only 2.5 secs to respond to a reversal manouvre (which you may have triggered by not following what TCAS told you in the first place!)
Finally it's quite important to transmit your "TCAS RA" as soon as possible, because ONLY THEN will ATC stop attempting to 'control' you for collision avoidance!
The thoughts above were not just picked up in a sim, or from a study guide! TCAS makes calculations incredibly fast, and transmits that 'coordinated' information to both you and the threat extremely quickly too! A great piece of kit!
Always bear in mind TCAS will issue an RA whenever it thinks the closest point of approach of a target is closer than it's criteria allow. That doesn't NECESSARILY mean it is predicting a 'zero/zero' aka 'collision'!
In fact, that is a VERY rare prediction.
Finally (finally!) During a TCAS event, I believe TCAS information is instantly downloaded to a ground station?? Perhaps someone may confirm?
EXENG: If you had waited for your RA you would never have had to fly your max rate climb. Firstly because TCAS cannot demand one, but more importantly because, once RA is activated, any manouvres are coordinated with the threat a/c. They 'talk' to each other. (and very, very quickly too!!)
This coordination is also why you should NEVER manouvre in opposition to TCAS commands, REGARDLESS of what you may 'see' out the window! To do so will likely exacerbate the avoidance manouvre required! (Or ultimately cause a collision!)
Yes you have 5 secs to respond to a TCAS RA, but only 2.5 secs to respond to a reversal manouvre (which you may have triggered by not following what TCAS told you in the first place!)
Finally it's quite important to transmit your "TCAS RA" as soon as possible, because ONLY THEN will ATC stop attempting to 'control' you for collision avoidance!
The thoughts above were not just picked up in a sim, or from a study guide! TCAS makes calculations incredibly fast, and transmits that 'coordinated' information to both you and the threat extremely quickly too! A great piece of kit!
Always bear in mind TCAS will issue an RA whenever it thinks the closest point of approach of a target is closer than it's criteria allow. That doesn't NECESSARILY mean it is predicting a 'zero/zero' aka 'collision'!
In fact, that is a VERY rare prediction.
Finally (finally!) During a TCAS event, I believe TCAS information is instantly downloaded to a ground station?? Perhaps someone may confirm?
Last edited by 4468; 9th Jun 2013 at 10:26.
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If so, you show a comical (and if you're actually a pilot, worrying) lack of understanding of TCAS.
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TCAS can issue commands that exceed the performance capability of the NG.
Why do we turn off the autothrottle on the NG? Simply because you don't know what you will get if you don't. If you are climbing with N1, a manual TCAS descent will not change this. You will then descend with climb N1 and enter overspeed really fast. You will get the overspeed clacker and will have to figure out why, at the same time as you need to fly the aircraft inside the TCAS safe zone. A very common pilot reflex to overspeed is to raise the nose of the aircraft. Not a smart thing to do in this situation.
I've had 3 real TCAS RA's, excluding Monitor VS. Click, click, fly outside the killzone smoothly. The passengers or cabin crew never noticed anything.
Monitor VS are being modified into Maintain altitude (or something to that effect), since pilots don't understand that a Monitor VS doesn't tell you to do anything but monitor. They start to manouver and often will make the situation worse.
I'm not surprised some pilots overreact to RA's. It is normally new pilots, or pilots new to TCAS who do this. I used to think it was a fast, emergency manouver myself when I was first introduced to TCAS. I have had a 200 hr marvel in the right seat who tried to point the aircraft skywards after a TA, not sure what he would hav done with a RA.
Why do we turn off the autothrottle on the NG? Simply because you don't know what you will get if you don't. If you are climbing with N1, a manual TCAS descent will not change this. You will then descend with climb N1 and enter overspeed really fast. You will get the overspeed clacker and will have to figure out why, at the same time as you need to fly the aircraft inside the TCAS safe zone. A very common pilot reflex to overspeed is to raise the nose of the aircraft. Not a smart thing to do in this situation.
I've had 3 real TCAS RA's, excluding Monitor VS. Click, click, fly outside the killzone smoothly. The passengers or cabin crew never noticed anything.
Monitor VS are being modified into Maintain altitude (or something to that effect), since pilots don't understand that a Monitor VS doesn't tell you to do anything but monitor. They start to manouver and often will make the situation worse.
I'm not surprised some pilots overreact to RA's. It is normally new pilots, or pilots new to TCAS who do this. I used to think it was a fast, emergency manouver myself when I was first introduced to TCAS. I have had a 200 hr marvel in the right seat who tried to point the aircraft skywards after a TA, not sure what he would hav done with a RA.
Last edited by ManaAdaSystem; 12th Jun 2013 at 08:22.
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To much all you said I think
Hand fly with throttle and York ,is your first lesson when fly.
When ra , 25seconds to impact. For a high speed flying object ,it is to much.maybe a little Change in attitude will Change the flying path and make you "safe". So what I think is be easy and not be panic.just follow the rules.
When ra , 25seconds to impact. For a high speed flying object ,it is to much.maybe a little Change in attitude will Change the flying path and make you "safe". So what I think is be easy and not be panic.just follow the rules.
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john_smith
Do you have an FCOM reference for that? Mine (A320 and330) say that the V/S is optimised to avoid.. and V/S changes are minimised.
On the Airbus (not sure if its type specific or not: I suspect not) TCAS will only demand either a 1500fpm or 2500fpm ROC or ROD. Those are the only two possible options for climb or descent RAs.
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If you have the new TCAS software that directs 90 degree turns you don't have to worry about climbing. :-/
Incident: LAN B788 and LAN B788 near Lima on Jun 11th 2013, near collision
Incident: LAN B788 and LAN B788 near Lima on Jun 11th 2013, near collision
The latest TCAS is 7.1 and it does not issue turn instructions. I suspect that the crew who elected to turn did so without TCAS input. As the other aircraft was climbing their TCAS was almost certainly giving descend which they didn't do. That would explain why the first aircraft climbed 800ft when a "normal" RA would only require 500/600ft to generate "clear of conflict".
The latest TCAS is 7.1 and it does not issue turn instructions. I suspect that the crew who elected to turn did so without TCAS input.
Can I add my two pennorth, some of which has already been mentioned.
I am constantly surprised by pilots talking about the 'kill zone' and over stressing aircraft to 'escape' and thinking they are about to 'die', as if they are driving along a motorway and suddenly see a car coming towards them in the opposite direction. Nothing could be further from the truth.
Your TCAS is constantly interrogating all the aircraft around it, (can't remember how many, but it is dozens), and assessing them all for threats. It will give warnings (TAs) if it sees proximate traffic, and avoidance advice (RAs) if a conflict is predicted.
TCAS units all talk to each other. If an RA is required the two aircraft's TCAS units will talk to each other and agree a plan. One will decide to go up, the other down. One makes the final decision, and they both agree which one will be the master according to which one has the lowest squawk code. (If one aircraft cannot react properly, for example if it is on one engine, the other aircraft will double its avoidance if necessary. This is why you select TA only on your TCAS if you've had engine failure.)
TCAS will issue an RA to its pilots with 30 seconds to the predicted conflict. Look at your watch now and watch the second hand for 30 seconds. It's a loooong time! All that is needed therefore is a GENTLE climb, or descent, or maintain what you are doing, and the aircraft will pass harmlessly.
If some idiot decides to 'haul on the controls' they might well put themselves into conflict with other traffic above or below them, which might trigger further RAs and massively complicate what should have been a very gentle and controlled manoeuver. If some idiot decides to ignore both TCAS computers and make up their own avoidance or do the opposite of what they are told, then both units will recalculate their avoidance plan and this is where changes of instruction come from.
To sum up,
-Nobody is within milliseconds of crashing when a TCAS RA is issued.
-All that is needed is a gentle change of vertical speed - sometimes not even that, just maintain the vertical speed you are doing.
-Always obey TCAS RAs, do NOT do your own thing - do not make decisions based on what you might see out of the window. You don't know if the aircraft you can see is the conflict aircraft, and if you choose the 'wrong' aircraft you might do the wrong thing. Remember, the TCAS units are talking to all the other TCAS units around you, most of which you cannot see. TCAS will 'see' a conflict aircraft at least a minute before you will.
- don't panic - as long as you start to do what the TCAS IVSI display tells you within 2.5 seconds, (and you will be prepared to react already because you will have been warned by the TA), there will be absolutely NO drama whatsoever.
- there is no need to haul on the controls, the TCAS will give you warning with plenty of time for you to react safely and gently.
I am constantly surprised by pilots talking about the 'kill zone' and over stressing aircraft to 'escape' and thinking they are about to 'die', as if they are driving along a motorway and suddenly see a car coming towards them in the opposite direction. Nothing could be further from the truth.
Your TCAS is constantly interrogating all the aircraft around it, (can't remember how many, but it is dozens), and assessing them all for threats. It will give warnings (TAs) if it sees proximate traffic, and avoidance advice (RAs) if a conflict is predicted.
TCAS units all talk to each other. If an RA is required the two aircraft's TCAS units will talk to each other and agree a plan. One will decide to go up, the other down. One makes the final decision, and they both agree which one will be the master according to which one has the lowest squawk code. (If one aircraft cannot react properly, for example if it is on one engine, the other aircraft will double its avoidance if necessary. This is why you select TA only on your TCAS if you've had engine failure.)
TCAS will issue an RA to its pilots with 30 seconds to the predicted conflict. Look at your watch now and watch the second hand for 30 seconds. It's a loooong time! All that is needed therefore is a GENTLE climb, or descent, or maintain what you are doing, and the aircraft will pass harmlessly.
If some idiot decides to 'haul on the controls' they might well put themselves into conflict with other traffic above or below them, which might trigger further RAs and massively complicate what should have been a very gentle and controlled manoeuver. If some idiot decides to ignore both TCAS computers and make up their own avoidance or do the opposite of what they are told, then both units will recalculate their avoidance plan and this is where changes of instruction come from.
To sum up,
-Nobody is within milliseconds of crashing when a TCAS RA is issued.
-All that is needed is a gentle change of vertical speed - sometimes not even that, just maintain the vertical speed you are doing.
-Always obey TCAS RAs, do NOT do your own thing - do not make decisions based on what you might see out of the window. You don't know if the aircraft you can see is the conflict aircraft, and if you choose the 'wrong' aircraft you might do the wrong thing. Remember, the TCAS units are talking to all the other TCAS units around you, most of which you cannot see. TCAS will 'see' a conflict aircraft at least a minute before you will.
- don't panic - as long as you start to do what the TCAS IVSI display tells you within 2.5 seconds, (and you will be prepared to react already because you will have been warned by the TA), there will be absolutely NO drama whatsoever.
- there is no need to haul on the controls, the TCAS will give you warning with plenty of time for you to react safely and gently.
Last edited by Uplinker; 27th Feb 2014 at 06:23.
One makes the final decision, and they both agree which one will be the master according to which one has the lowest squawk code.
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Hi john_smith,
See page 13:
http://www.skybrary.aero/bookshelf/books/106.pdf
"2000 ft/min.
1000 ft/min.
500 ft/min.
0 ft/min.
RA requires one of
these vertical speeds"
All of my TCAS warnings have been due to other traffic with big ROD / ROC approaching their cleared levels. If only they observed ICAO Recommendation:
"Unless otherwise specified in an air traffic control instruction, to avoid unnecessary airborne collision avoidance system (ACAS II) resolution advisories in aircraft at or approaching adjacent altitudes or flight levels, operators should specify procedures by which an aeroplane climbing or descending to an assigned altitude or flight level, especially with an autopilot engaged, may do so at a rate less than 8 m/sec or 1 500 ft/min (depending on the instrumentation available) throughout the last 300 m (1 000 ft) of climb or descent to the assigned level when the pilot is made aware of another aircraft at or approaching an adjacent altitude or flight level."
See http://www.skybrary.aero/bookshelf/books/1804.pdf
So with say 3,000 ft per min ROC, pilots will have to have started to change their VS towards 1500 ft per min before 2,000 feet to go - else it is too late and the AP mode will have changed to ALT*.
TCAS will only demand either a 1500fpm or 2500fpm ROC or ROD.
http://www.skybrary.aero/bookshelf/books/106.pdf
"2000 ft/min.
1000 ft/min.
500 ft/min.
0 ft/min.
RA requires one of
these vertical speeds"
All of my TCAS warnings have been due to other traffic with big ROD / ROC approaching their cleared levels. If only they observed ICAO Recommendation:
"Unless otherwise specified in an air traffic control instruction, to avoid unnecessary airborne collision avoidance system (ACAS II) resolution advisories in aircraft at or approaching adjacent altitudes or flight levels, operators should specify procedures by which an aeroplane climbing or descending to an assigned altitude or flight level, especially with an autopilot engaged, may do so at a rate less than 8 m/sec or 1 500 ft/min (depending on the instrumentation available) throughout the last 300 m (1 000 ft) of climb or descent to the assigned level when the pilot is made aware of another aircraft at or approaching an adjacent altitude or flight level."
See http://www.skybrary.aero/bookshelf/books/1804.pdf
So with say 3,000 ft per min ROC, pilots will have to have started to change their VS towards 1500 ft per min before 2,000 feet to go - else it is too late and the AP mode will have changed to ALT*.
Hi DaveReid,
You might well be right, I was told it was the squawk. Anyway, the two TCAS involved do have a way of nominating which becomes the master.
Hi Rudderrat,
Yes, I personally think it's high time there was an autopilot or altitude capture software update installed to all aircraft which softened the rate of climb/descent as aircraft approached their cleared level to avoid the sort of nuisance TAs you refer to.
You might well be right, I was told it was the squawk. Anyway, the two TCAS involved do have a way of nominating which becomes the master.
Hi Rudderrat,
Yes, I personally think it's high time there was an autopilot or altitude capture software update installed to all aircraft which softened the rate of climb/descent as aircraft approached their cleared level to avoid the sort of nuisance TAs you refer to.