Selection of TA/RA during emergency descents?

Vector4Food

This job would be easier without all the airplanes
Watching this training video for a 777, I noticed part of the checklist was to turn the TCAS to TA. Which someone can please correct me means no resolution advisory.

Is this a normal part of any checklist during an unplanned descent?

Here's the video I'm speaking of:

 
Ta you get the traffic traffic alert. I've never seen that before, but when you're descending like a bat out of hell, I'll be surprised if you do get an RA.
 
As a prior Avionics Technician with a somewhat firm understanding on the TCAS system, I would offer an educated guess.

Since the TCAS systems talk to each other between the two conflicting aircraft, deciding who should climb or descend, selecting TA only probably announces to the other system that this system isn't going to be adhering to any RA requirements. Allows the sole RA aircraft to make a better decision about getting out of the way.

"I'm not moving, so you better figure it out..."
 
just form the title of the video it looks like they are doing single engine work, which most checklist will have selecting TA only.
 
I don't know if you'd be able to comply with the climb gradient requirements for a RA at single engine. You're expected to be able to start a climb at 1500-2000fpm when you get CLIMB CLIMB, and then increase from there if you get INCREASE CLIMB RA.

Additionally, if its an emergency descent you need to accomplish but the TCAS descides that it would be most efficient for you to climb instead to avoid an intruder what would you do? Either way you're in trouble.
 
That is exactly correct, the two aircraft are talking to each other, and TA/RA they are both agreeing to the resolution, hence why you do not ignore the command, i believe the DHL midair with the Russian airliner had to do with ignoring commands from the TCAS.

When you put it in TA only, your aircraft is essentially telling the other, you will not win this game of chicken...
 
Anybody have the video of Air Canada and whiskey nEarly colliding? They both had RA's to climb and descend into each other? I saw it during recurrent a while back. It happen in Indy ARTCC AO.
 
Anybody have the video of Air Canada and whiskey nEarly colliding? They both had RA's to climb and descend into each other? I saw it during recurrent a while back. It happen in Indy ARTCC AO.
I would love to see this!


Also thanks for the replies as always. Love this place!

Edit: that sounded way too enthusiastic about a potential disaster.... I mean love to see the video as a training aid!
 
In the event of an emergency decent, you are talking 8-10K fpm down for any CRJ variant with the actual profile. Automation will auto-recover beyond 10Kfpm in decent, even if you try to manually push more than DOWN 10.0 VS. TCAS or beyond Vmo/Vmm in speed mode. TCAS II sees that in RA/TA mode to the other aircraft, hence the "next generation".

-10KFPM vs -0-... yea... let's see who will change course. 320kts indicated/ 380-480 TAS@ 10-12 degrees down angle (8-10K FPM) vs. straight and level in any other variant.... Let's not get into trig and geometry of that, TCAS II is designed for that already. To make life more "common sense prevails", profiles tend to call for ATC notification.

I can confirm this across multiple 121's and the type training material for a type that can operate at FL510, in this case- automatic/automated decent in the range of 10-15KFPM down to 10K (with respect to terrain) without doing anything but putting the mask on and realizing the problem after the aircraft tells you.

Maybe I am missing something, just going by the bombardier GMM/AMM, plus the FAA approved profile for the CL-65 series. If cabin pressure goes nuts, it's mask and "full down bubble".
 
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