PPRuNe Forums

PPRuNe Forums (https://www.pprune.org/)
-   Tech Log (https://www.pprune.org/tech-log-15/)
-   -   TCAS RA (https://www.pprune.org/tech-log/567721-tcas-ra.html)

qualityjet 15th Sep 2015 18:08

TCAS RA
 
Hi!

What do you think, can TCAS give you a climb command when you are flying your max FL? So does it know anything about ac's performance?

Just thinking...

deptrai 15th Sep 2015 18:19

Follow the RA, trade speed/inertia for height (and avoid stalling), you're trying to avoid a collision, not to cruise. Generally TCAS are not aware of aircraft performance, though many inhibit climb RA above a certain altitude (check with your outfit). Where that is the case, when 2 level a/c are on collision course, TCAS will generate a descend RA for one and keep the other level.

Wizofoz 15th Sep 2015 18:32

TCAS takes performance into consideration- it will give you a climb at max altitude, but one your residual performance can handle.

tubby linton 15th Sep 2015 20:14

At altitude the pitch change to achieve the required miss is quite small if you have a TAS of 7-8 miles per minute.

deptrai 15th Sep 2015 20:16

TCAS takes performance into consideration- it will give you a climb at max altitude, but one your residual performance can handle.

Afaik TCAS is NOT aware of actual performance limits, e.g. degraded performance due to loss of an engine, but some limits have been taken into consideration during certification.

http://www.faa.gov/documentLibrary/m...-55C_CHG_1.pdf :


(1) Aircraft not inhibited to climb when at maximum certified altitude should climb in response to TCAS climb RAs.
(2) Aircraft that are climb-inhibited from TCAS climbs at maximum certified altitude will be issued a “DO NOT DESCEND” RA.
and (courtesy of airbus)


AC 20-131A defines the maneuvers that the aircraft must be able to perform.
• In particular, the aircraft must prove that it can respond to a TCAS RA CLIMB order, even when it is at its maximum altitude.
( AC 20-131A here: https://www.faa.gov/regulations_poli...cumentID/22190 )

Wizofoz 16th Sep 2015 04:40

Correct depral- so you CAN comply with an RA even if it is "CLIMB" while at max altitude.

Also right about single engine- which is why S/E checklists (on Boeing anyway) include putting TCAS into TA only.

Thai Pom 16th Sep 2015 05:18

During the installation there is Pin Programming that is done that sets the aircraft ceiling. TCAS should not issue a climb RA if this height will be reached.


Cheers, TP

latetonite 16th Sep 2015 06:36

..and the pin is changed with Every weight?

Wizofoz 16th Sep 2015 06:39

Thai Pom,

Not the impression I was under- do you have a reference?

Thai Pom 16th Sep 2015 06:44

Hopefully the answer you want.
 
No it is part of the certified engineering package, based on the certified Ceiling from the OIM. I believe in later installs it can be changed visa the MCDU but I am not sure on that.


TP

deptrai 16th Sep 2015 07:16

Generally aircraft have been tested that they can comply with RAs in most scenarios. During installation, various inhibit parameters can be set, most obviously AGL, but also configuration; this will depend on manufacturer/type, and your outfit.

JAR 16th Sep 2015 22:47

Embraer 170-195:

TCAS​ WARNING​ INHIBITIONS

No​ CLIMB​ commands​ or​ INCREASE​ CLIMB​ commands​ are​ issued​ at​ or above​ 34000​ ft​ MSL.​

Pin Head 17th Sep 2015 00:49

Read a circular once from the European safety agency before EAsA and ITBASICALLY implied instigate some sort of a climb (even the slightest) at max altitude as it will relay and coordinate with the other a/c and force him into a descent.

Pin

GlobalNav 17th Sep 2015 21:55

"( AC 20-131A here: https://www.faa.gov/regulations_poli...cumentID/22190 )"

There is a more current AC now - AC 20-151B and here's a brief excerpt:
2-16. Aircraft Performance Considerations. Use paragraphs 2-16 through 2-17 and Table 1 of this AC to help you evaluate the need to inhibit TCAS II CLIMB and/or INCREASE CLIMB RAs resulting from inadequate aircraft climb performance. The collision avoidance maneuvers posted as RAs by TCAS II assume an aircraft’s ability to safely achieve them. If it’s likely the required response to CLIMB and INCREASE CLIMB RAs are beyond the performance capability of the aircraft, then TCAS II must know beforehand so it can change strategy and issue an alternative RA.

ACMS 17th Sep 2015 23:30

Really?
So what if both Aircraft are operating at their max altitudes?

Bang?

Doubt it.

West Coast 18th Sep 2015 00:31

Page not found

Thai Pom 18th Sep 2015 01:12

ACMS
 
One of them would be given the "descend" command ?

ACMS 18th Sep 2015 03:39

Thai----obviously one would, posters here said that a RA to climb would not be given above Max Alt.

I'm simply pointing out that idea is wrong.

ACMS 18th Sep 2015 03:46

From the A330 FCTM, it says you MUST follow the RA even if above Max Alt

If a RA is generated:
• The flight crew must always follow the TCAS RA orders in the correct direction, even:
‐ If the TCAS RA orders are in contradiction with the ATC instructions
‐ At the maximum ceiling altitude with CLIMB, CLIMB or INCREASE CLIMB, INCREASE CLIMB TCAS RA orders
‐ If it results in crossing the altitude of the intruder.

deptrai 18th Sep 2015 05:46

that a RA to climb would not be given above Max Alt. I'm simply pointing out that idea is wrong.

again, it depends on type.


All times are GMT. The time now is 23:20.


Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.