PPRuNe Forums - Manoeuvering in response to TCAS RA

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Manoeuvering in response to TCAS RA

In cruise with autopilot engaged and RA suddenly occurs. Should you immediately disengage autopilot/autothrottle and flight director at same time immediately following the RA commands?

Or:

Leave automatics engaged and use CWS or select VS mode to follow RA commands?
What are the chances of a delay in making the right MCP selection and thus causing a close shave?

Or worse still, press the wrong autopilot selection buttons and the autopilot fails to climb/descend?

Or, to minimise any automatic pilot mode delay following the RA command, is it generally a safer bet to disengage the automatics and get cracking without delay manually?

At least in my outfit, the following applies: TA: hands on controls but don't move anything, look for traffic. RA: disconnect and follow RA command smoothly but firmly. We don't have autothrottle, so that's not an issue ;)

Greetings
Auto pîlot OFF for TCAS RA to respond to the TCAS evasive maneuvre, Auto throttle OFF is a part of the reflexive behavior however it is less critical than the Auto pilot disconnection. :ok: for the Flight Director it is better to leave it ON, because it will show you which way to go when out of conflict.:}

Rather simple issue that bfisk has awnsered already correcly.
Only thing I would lke to add is to disengage the automatics IMMEDIATLELY to follow the RA command.

...fiddeling around with the MCP might be the last thing you ever do!:eek:

In the Airboos frog thingey -

TA - hands on gamestick but do nothing

RA - FDs off (puts AT in Speed hold), then AP off

Clear of Conflict: FDs ON, AP on, pull ALT (OPEN CLB/DES will bring the plane back to asigned level)

At Asigned level: Yell at ATC and tell him your gonna report his ass!

Slasher, your'e the man:ok:

If you have A/THR

Always check SPEED mode is active after turning off the FDs
Otherwise you can have serious problems.

I don't think disconnecting A/THR is a sensible thing to do, though I guess it depends on airplane and procedures.

Quote:

Originally Posted by ICAO Doc 9863 (ACAS)

5.2.1.8 Respond to RAs by disconnecting the autopilot and by using prompt, smooth control inputs;
manoeuvre in the direction and with the vertical rate ACAS requires. To achieve the required vertical rate
(normally 1 500 ft per minute) on aircraft where the RA is displayed on a vertical speed indicator (VSI), it is
recommended that the aircraft’s pitch be changed using the guidelines shown in the table below. Referring
to the VSI or vertical speed tape, make any further pitch adjustments necessary to place the vertical speed
in the green area.

Quote:

Originally Posted by ICAO Doc 9863 (ACAS)

5.2.1.9 For ACAS to provide safe vertical separation, the PF is expected to initiate the appropriate
RA manoeuvre within 5 seconds of when the RA is first displayed. Deviations from assigned altitude, when
responding to an RA, typically will be no more than 300 to 500 ft. RA manoeuvres should use vertical
speeds within the green areas, or the indicated pitch angle, and avoid red areas on vertical speed indicators
or tapes, or outlined pitch avoidance areas.

Quote:

Originally Posted by ICAO Doc 8168 (flight proc)

c) in the event of an RA, pilots shall:
1) respond immediately by following the RA as indicated, unless doing so would jeopardize the safety of the
aeroplane;

Conclusion, never follow an RA with AP engaged...whatever the A/C type.

Quote:

Conclusion, never follow an RA through automation...whatever the A/C type.

True for current types, but in future things might be different....

Airbus studies emergency traffic avoidance system to act without pilots-22/03/2006-Toulouse-Flight International

Slasher says FDs off first. Don't know if that was intentional but I have heard it before. I find this a little odd seeing that the intention during a RA is to manouvre away as quickly as possible.

Let's see what the ACAS III is all about first and we will talk about the future when it arrives...

Funny quote from your 2006 article:

Quote:

He is not specific about if and when the new system will enter service, but says it will probably be available on the A350 when deliveries begin in 2010

FDs OFF is true for all Airbus FBW.

Airbus:
TA: call out "TCAS I HAVE CONTROLS"

RA:
FIRST: AP OFF (you are now hand flying)
SECOND: FDs OFF (BOTH, please!) (A/THR reverts to SPEED)

Now you can pitch up or down smoothly but promptly to put the V/S in the green.

it is interesting to note that on parallel approaches a hand flown break out is also necessary

Could be wrong but I'm fairly sure that on Boeing you leave the FD on and follow it's command as it is responding to the RA? I'm not current so could easily be wrong.

Quote:

it is interesting to note that on parallel approaches a hand flown break out is also necessary

Any maneuver requiring prompt response will be hand flown: TCAS RA, PRM break-out, avoiding action, (E/)GPWS...

Quote:

In cruise with autopilot engaged and RA suddenly occurs. Should you

Do what your FCOM or FCTM says!

On my machine, when an RA occurs, pushing the AP disconnect button will make the FD bars automatically go away. Neat.

Bloggsie

I bet you are getting in plenty of practise in the sim for future reference:ok:

J:E

Am I the only one that finds this thread deeply scary?

No! (Plus post padding)

post padding?...look who's talking...