It is supposed to be a quarter g maneuver

Topics related to accidents, incidents & over due aircraft should be placed in this forum.

Moderators: lilfssister, North Shore, ahramin, sky's the limit, sepia, Sulako

Post Reply
pelmet
Rank 11
Rank 11
Posts: 4601
Joined: Tue Jun 14, 2005 2:48 pm

It is supposed to be a quarter g maneuver

Post by pelmet »

I did overhear a captain brief once to the cabin crew about the TCAS system and how they could expect to possibly float around(or however it was worded) in the event of a maneuver in response to an alert. Not true. The Resolution advisory(RA) gives enough time to do what is called a quarter g maneuver(half g for a reversal). ie. You will be at 1.25g or 0.75 g. Unfortunately some grossly over-react. Full control input is rarely necessary in an airliner. A nice smooth input to follow the RA command works just fine. Plus on the Airbus, if you don't press the takeover button, your input is added to the other pilots, up to max allowable input.

https://app.ntsb.gov/pdfgenerator/Repor ... L&IType=LA

"During climb, the TCAS accrued a TA then a RA down advisory 'don't climb greater than 500 fpm.' The crew simultaneously operated their respective side stick controls when the captain responded with an abrupt maneuver without making a verbal announcement that he was taking command. Input from both side sticks changed the aircraft nose-up pitch from 0.7 degrees to 4.22 degrees in 1.1 second and an aft galley g load from -0.36 g's to 2.27 g's. Subsequently, the Captain Side Stick Position gave an aircraft pitch change to 2.11 degrees nose-down and an aft galley CG of -0.76 g's in a span of one second. Both Side Stick positions cumulatively gave 1.8 degrees nose-up and 2.09 g's at the aft galley in 1.2 seconds. The VFR traffic had visual contact on the Airbus and both aircraft were advised by ATC that the traffic was not a factor. The seat belt sign had been turned 'OFF' and the FA's were preparing for passenger service."

"At 5 minutes 12 seconds after takeoff, during the combined control input, the Captain Side Stick position indicted a full nose down input."

" The flight attendants (enclosed statements) described the event with the following phraseology:
three strong consecutive jolts that threw me to the ceiling, floor,
and also against a galley wall 5 times,
hit by beverage carts, containers, and other service items,
hefty jolts which occurred without warning,
thrown approximately 5 times against the ceiling,
galley looked like a battle field,
aircraft jolted strongly and we were thrown some 50 centimeters into the air,
followed by another, much stronger blow,
thrown against the ceiling with great force several times, each time falling back to the floor,
thrown around the galley several times without warning,
thrown against the ceiling and the floor several times, and twice lifted some 10 centimeters from the floor."
---------- ADS -----------
  

KissPlusOne
Rank 1
Rank 1
Posts: 45
Joined: Tue Dec 11, 2018 12:07 pm

Re: It is supposed to be a quarter g maneuver

Post by KissPlusOne »

Those poor flight attendants.
---------- ADS -----------
  

User avatar
'97 Tercel
Rank 7
Rank 7
Posts: 529
Joined: Fri Jul 19, 2013 5:19 pm

Re: It is supposed to be a quarter g maneuver

Post by '97 Tercel »

I think the RA voice guy is too panicky-sounding.
---------- ADS -----------
  

ahramin
Rank Moderator
Rank Moderator
Posts: 5928
Joined: Tue Feb 17, 2004 5:21 pm
Location: Vancouver

Re: It is supposed to be a quarter g maneuver

Post by ahramin »

In my experience responding to TAs & RAs are the single most poorly taught item in the entire initial and recurrent training syllabus.
---------- ADS -----------
  

digits_
Rank 10
Rank 10
Posts: 2788
Joined: Mon Feb 14, 2011 2:26 am

Re: It is supposed to be a quarter g maneuver

Post by digits_ »

Yups. With a sim instructor who knows it is happening and then starts rushing you while you are still processing if it is going to be a climb or descent, and how much you need. Not realistic at all. You don't have much time, but you do have some time. It's never a good thing when you are pushed into blindly doing something.
---------- ADS -----------
  
As an AvCanada discussion grows longer:
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship

User avatar
Canoehead
Rank 8
Rank 8
Posts: 898
Joined: Wed Jan 05, 2005 11:08 pm
Location: YEE 220 @ 4

Re: It is supposed to be a quarter g maneuver

Post by Canoehead »

digits_ wrote:
Sat Feb 29, 2020 9:25 am
Yups. With a sim instructor who knows it is happening and then starts rushing you while you are still processing if it is going to be a climb or descent, and how much you need. Not realistic at all. You don't have much time, but you do have some time. It's never a good thing when you are pushed into blindly doing something.
How does the sim instructor play into it?
---------- ADS -----------
  

GRK2
Rank 3
Rank 3
Posts: 145
Joined: Sun Aug 02, 2015 5:04 am

Re: It is supposed to be a quarter g maneuver

Post by GRK2 »

digits_ wrote:
Sat Feb 29, 2020 9:25 am
Yups. With a sim instructor who knows it is happening and then starts rushing you while you are still processing if it is going to be a climb or descent, and how much you need. Not realistic at all. You don't have much time, but you do have some time. It's never a good thing when you are pushed into blindly doing something.
I'm pretty sure you're not required to "guess" which recovery maneuver a TCAS RA is going to give you! All you are required to do for a ride is to follow the RA and use your SOP's for your type to act, then recover. If you're being asked to guess the direction and rush for this, how about you tell your instructor to park the sim and when he/she can explain just exactly the standard required for the RA, then you can go back to training or complete your ride.I am also pretty sure that no one could possibly have the computing power in their brain needed to produce the RA actions needed. If you're being challenged to guess it's purely negative training and you need to have a word with your standards Captain(s)
---------- ADS -----------
  

digits_
Rank 10
Rank 10
Posts: 2788
Joined: Mon Feb 14, 2011 2:26 am

Re: It is supposed to be a quarter g maneuver

Post by digits_ »

GRK2 wrote:
Sat Feb 29, 2020 10:01 am
digits_ wrote:
Sat Feb 29, 2020 9:25 am
Yups. With a sim instructor who knows it is happening and then starts rushing you while you are still processing if it is going to be a climb or descent, and how much you need. Not realistic at all. You don't have much time, but you do have some time. It's never a good thing when you are pushed into blindly doing something.
I'm pretty sure you're not required to "guess" which recovery maneuver a TCAS RA is going to give you! All you are required to do for a ride is to follow the RA and use your SOP's for your type to act, then recover. If you're being asked to guess the direction and rush for this, how about you tell your instructor to park the sim and when he/she can explain just exactly the standard required for the RA, then you can go back to training or complete your ride.I am also pretty sure that no one could possibly have the computing power in their brain needed to produce the RA actions needed. If you're being challenged to guess it's purely negative training and you need to have a word with your standards Captain(s)
Who says anything about guessing? It takes a fraction of a second to process the input of the TCAS system. You see a warning, and you have to process what input would give you the required climb or descent rate. A 500 fpm climb requires a different control input than a 2500 ft climb. In order not to unnecessarily over correct, it's important that you figure that out.

If your sim instructor is rushing you for a correction right away, instead of half a second later, you significantly increase the risk of reacting too much. That doesn't matter in the sim, but for the unlucky flight attendants in the described event, it makes a big difference.

The TCAS RA's I've encountered in real life have always been more relaxed than the ones in the sim.
Canoehead wrote:
Sat Feb 29, 2020 10:00 am
digits_ wrote:
Sat Feb 29, 2020 9:25 am
Yups. With a sim instructor who knows it is happening and then starts rushing you while you are still processing if it is going to be a climb or descent, and how much you need. Not realistic at all. You don't have much time, but you do have some time. It's never a good thing when you are pushed into blindly doing something.
How does the sim instructor play into it?
They know it is going to happen, because they programmed it. In their mind they already know you'll need to climb or descend. The trainee will need part of a second to process that information. I've had sim instructors that demanded an instanteneous respond, basically unrealisticaly rushing you. That's how you get a possibly "panicky" reaction like in the first post.

Or when you are executing a controlled climb, start shouting "CLIMB CLIMB CLIMB" for a more aggressive climb, even though the TCAS only requires a 500 fpm climb. That's unnecessary and counter productive.
---------- ADS -----------
  
As an AvCanada discussion grows longer:
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship

pelmet
Rank 11
Rank 11
Posts: 4601
Joined: Tue Jun 14, 2005 2:48 pm

Re: It is supposed to be a quarter g maneuver

Post by pelmet »

Usually pretty straight forward. Follow the RA voice and PFD commands in a relaxed manner at one quarter g. Usually no rush, just sit and wait for commands to follow after the standard lights on, advise ATC and look out the window.

Maybe it is the guys feeling rushed that do these aggressive inputs.
---------- ADS -----------
  

GRK2
Rank 3
Rank 3
Posts: 145
Joined: Sun Aug 02, 2015 5:04 am

Re: It is supposed to be a quarter g maneuver

Post by GRK2 »

digits_ wrote:
Sat Feb 29, 2020 1:01 pm
GRK2 wrote:
Sat Feb 29, 2020 10:01 am
digits_ wrote:
Sat Feb 29, 2020 9:25 am
Yups. With a sim instructor who knows it is happening and then starts rushing you while you are still processing if it is going to be a climb or descent, and how much you need. Not realistic at all. You don't have much time, but you do have some time. It's never a good thing when you are pushed into blindly doing something.
I'm pretty sure you're not required to "guess" which recovery maneuver a TCAS RA is going to give you! All you are required to do for a ride is to follow the RA and use your SOP's for your type to act, then recover. If you're being asked to guess the direction and rush for this, how about you tell your instructor to park the sim and when he/she can explain just exactly the standard required for the RA, then you can go back to training or complete your ride.I am also pretty sure that no one could possibly have the computing power in their brain needed to produce the RA actions needed. If you're being challenged to guess it's purely negative training and you need to have a word with your standards Captain(s)
Who says anything about guessing? It takes a fraction of a second to process the input of the TCAS system. You see a warning, and you have to process what input would give you the required climb or descent rate. A 500 fpm climb requires a different control input than a 2500 ft climb. In order not to unnecessarily over correct, it's important that you figure that out.

If your sim instructor is rushing you for a correction right away, instead of half a second later, you significantly increase the risk of reacting too much. That doesn't matter in the sim, but for the unlucky flight attendants in the described event, it makes a big difference.

The TCAS RA's I've encountered in real life have always been more relaxed than the ones in the sim.
Canoehead wrote:
Sat Feb 29, 2020 10:00 am
digits_ wrote:
Sat Feb 29, 2020 9:25 am
Yups. With a sim instructor who knows it is happening and then starts rushing you while you are still processing if it is going to be a climb or descent, and how much you need. Not realistic at all. You don't have much time, but you do have some time. It's never a good thing when you are pushed into blindly doing something.
How does the sim instructor play into it?
They know it is going to happen, because they programmed it. In their mind they already know you'll need to climb or descend. The trainee will need part of a second to process that information. I've had sim instructors that demanded an instanteneous respond, basically unrealisticaly rushing you. That's how you get a possibly "panicky" reaction like in the first post.

Or when you are executing a controlled climb, start shouting "CLIMB CLIMB CLIMB" for a more aggressive climb, even though the TCAS only requires a 500 fpm climb. That's unnecessary and counter productive.
No guessing needed, TCAS will tell you the maneuver, disconnect the AP (if you have one) Disconnect the AT (again, if you have one) and simply and gently follow the RA command. No guessing needed. If your SIM instructor is yelling at you he or she is a bit of a Tw*t and needs to calm the frik down.
---------- ADS -----------
  

User avatar
Canoehead
Rank 8
Rank 8
Posts: 898
Joined: Wed Jan 05, 2005 11:08 pm
Location: YEE 220 @ 4

Re: It is supposed to be a quarter g maneuver

Post by Canoehead »

digits_ wrote:
Sat Feb 29, 2020 1:01 pm
They know it is going to happen, because they programmed it. In their mind they already know you'll need to climb or descend. The trainee will need part of a second to process that information. I've had sim instructors that demanded an instanteneous respond, basically unrealisticaly rushing you. That's how you get a possibly "panicky" reaction like in the first post.

Or when you are executing a controlled climb, start shouting "CLIMB CLIMB CLIMB" for a more aggressive climb, even though the TCAS only requires a 500 fpm climb. That's unnecessary and counter productive.
I would question the knowledge of your sim instructor in that case.

Deviating from what the RA is commanding is incorrect and dangerous. If the RA is commanding something in a certain range, you follow that command. Your instructor suggesting you climb (or descend) more aggressively than what the TCAS is telling you suggests they don't really understand how TCAS works.
---------- ADS -----------
  

Maynard
Rank 6
Rank 6
Posts: 440
Joined: Wed Sep 24, 2008 8:33 am

Re: It is supposed to be a quarter g maneuver

Post by Maynard »

'97 Tercel wrote:
Fri Feb 28, 2020 9:20 pm
I think the RA voice guy is too panicky-sounding.
Maybe they’re different, but I had an RA and it was a calm normal paced “Adjust your vertical profile” the “traffic traffic” was the standard.
---------- ADS -----------
  
I guess I should write something here.

ReserveTank
Rank 3
Rank 3
Posts: 176
Joined: Thu Nov 29, 2012 6:32 am

Re: It is supposed to be a quarter g maneuver

Post by ReserveTank »

Usually, only a few degrees of pitch change is required to resolve an RA. Every time I go to recurrent, the other pilot overreacts to the RA, making unnecessarily abrupt control inputs. This is brought about by the panicky nature of the aural RA and the fact that even many of the sim instructors become tense on the controls during an RA. This leads to crews lacking the practice and knowledge that a small pitch change is sufficient to clear an RA.
---------- ADS -----------
  

pelmet
Rank 11
Rank 11
Posts: 4601
Joined: Tue Jun 14, 2005 2:48 pm

Re: It is supposed to be a quarter g maneuver

Post by pelmet »

ReserveTank wrote:
Sat Feb 29, 2020 9:03 pm
Usually, only a few degrees of pitch change is required to resolve an RA. Every time I go to recurrent, the other pilot overreacts to the RA, making unnecessarily abrupt control inputs. This is brought about by the panicky nature of the aural RA and the fact that even many of the sim instructors become tense on the controls during an RA. This leads to crews lacking the practice and knowledge that a small pitch change is sufficient to clear an RA.
I have had RA’s in several types in the sim and none of them sounded panicky although they do sound as they should.....firm but no panicky change in voice pitch/tone.

One has a pitch area to target(or avoid depending on which way you view it) and a vertical speed red and green area. I typically target a vertical speed in the green area but adjacent or close to the red area. Works well.

Panicky pilot reactions is why one type now has......automatic RA. Manufacturer claims a 50% reduction in inappropriate responses. Just leave the autopilot on and watch the automatics do their magic. We have it . So cool to watch.
---------- ADS -----------
  

Post Reply

Return to “Accidents, Incidents & Overdue Aircraft”