VNAV, Descend Via and Embray'ers

crazyjaydawg said:
Actually this is because the uncoupled side has an altitude that is off by more than 80 feet. The altimeters are within RVSM limits, but they're far enough off that the uncoupled box is constantly recalculating a new descent profile. That top of descent is within a minute of your current position (because you're damn close in altitude) but it's just far enough off that I gives you that warning chime that the uncoupled FMS wants to start down in less than 1 minute.

They only way to settle this is to unpair the FMSs (not an authorized procedure) or just write up the altimeters on the ground and have them re calibrated.

Btw cross checking altimeters upon leveling in RVSM and writing it down is a requirement. It could be rather eye-opening sometimes. Those Delta birds are getting old and cranky.
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Man how did you figure that out? I'm gonna sound so smart now when the noobs ask WTF is it doing??

Well, your altitude is off by more than 80' braj. You didn't know that?!?!
 
learhawkerbe400 said:
I always tell people if you're not using VNAV then turn it off. What's the point of leaving it magenta? All it will do is capture some random altitude you don't want it to.
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Descend and maintain means descend and maintain, which means FPA (FLCH).

Descend via means path.
 
You know i likes the ARTS 3E with the FDAT radar displays better than that stupid ACD set up or that STARS pos, i mean a square radar display no thanks and ill keep my paper strips also. what do you guys think about it ?
 
queeno said:
You know i likes the ARTS 3E with the FDAT radar displays better than that stupid ACD set up or that STARS pos, i mean a square radar display no thanks and ill keep my paper strips also. what do you guys think about it ?
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Non-radar is the basis of all ATC, as it has been explained to me, so I think keeping THAT skill current is probably a good idea too.
 
B767 said:
"Turn right 070. Airport 2 o'clock 9 miles. Do you have it?"

"In sight."

"Cleared for the visual 16R."

A few minutes later.

"Airline 123, turn right 145 to join final. 170 to LEETZ. You're number 1, contact tower 132.65."

"What the bloody hell?! You cleared us for the visual 5 minutes ago!"
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All.

The damned.

Time.

Every time.
 
Gotta love getting switched from 12R to 12L on the KKILR1 after you've already started down.

"Now descend via the KKILR1, 12 left transition..."

"Um, which one part of that transition is most important to you? Because the rest ain't gonna happen." :-)

Back on topic, does anybody know if the datalink winds (if that option is enabled) actually results in a modified path that makes crossing speeds work a little better?

Doesn't the Airbus get actual winds aloft in the vicinity from other nearby Airbus' and "remember" the winds in the area for 2 hours or something clever like that, which would at least partially explain why it does such a nice job meeting speed reductions on the way down on its own.

I gotta believe the 170/190 box can do a better job and it's just installed options (or the lack thereof) holding it back. ("Better" being a relative term, since the thing is still pretty darn sweet.)
 
jtrain609 said:
As a general rule, as long as you're allowed to continue to descend to the original altitude, being pulled off the arrival isn't a big deal as long as you pop it into FPA and keep descending at roughly the same rate you were at before the vector.

Then once you're back on, making a fix a hard altitude and doing a vertical direct gets you right back where you were.

It also tells you how screwed you are, because our box will tell us what the angle is on the vertical direct. You'll know right away if you won't be able to stay on the arrival.
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"Depends".

On the airbus, we have (technically) two managed descent modes, which are both "managed".

Here's the split. Once you start down a managed (VNAV) descent path, the airplane will start descending, join the desired vertical path and then assume that once you reach your path, that you will be in a constant descent to all other fixes on the profile as it planned.

Once you get off the lateral path, the aircraft will still presume you're going to continue descending, even though you've had a mode reversion to VS or "open" (same as FLCH).

So when you're back on path, the 'technique' is to re-cruise by re-inserting your cost-index or re-inserting some of the data on your approach flight phase page on your MCDU because until you do that, where the aircraft is still convinced you're descending as it planned previous to your departure from the managed (VNAV) path, even though you've been droning around in a different mode.

The distinction between geometric managed descent and a profile (I think that's what it's called, I'm having a brain fart, save me @PeanuckleCRJ) descent mixed in with a new runway and a new restriction is one of our leading causes of unstabilized approaches in the Airbus.

Things that aren't a problem for the Airbus are big problems in Boeings. Things that aren't a problem in Boeings are a big problem in Airbus. Mix in another few fleet types into an ATC environment that presupposes that all turboprops are Brasilias and all jets have the characteristics of mad dogs and CRJ's, we've got a recipe for hilarity.

Every time I'm arriving in SLC with a new pilot, I start the brief early, talk about the various ways they're going to attempt to bone us and with almost 100% certainty, they will (which is great because it's pre-briefed and we've talked about some mitigation techniques) or make up something completely new and unexpected when the inevitable "ZOOOOOOMG! Uhhh, here's a Gordian Knot, untie it! Contact tower on…"
 
woutlaw said:
Doesn't the Airbus get actual winds aloft in the vicinity from other nearby Airbus' and "remember" the winds in the area for 2 hours or something clever like that, which would at least partially explain why it does such a nice job meeting speed reductions on the way down on its own.
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We've got "History" winds from the inbound flight, but generally, there's a fleet-wide live-data wind uplink every X hours that we all get from actual data.

Well, except for the Douglas and the Boeing "Foster Child" fleets.
 
learhawkerbe400 said:
Man how did you figure that out? I'm gonna sound so smart now when the noobs ask WTF is it doing??

Well, your altitude is off by more than 80' braj. You didn't know that?!?!
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So after finishing consolidation and seeing this issue at least 3 times I am happy to have an answer. All the guys I've flown with have been clueless. I have pointed out the altimeter discrepancies. I'm surprised they let them get so bad. Either way, now I know. And knowing is half the battle, convincing the captain is the other half.
 
Autothrust Blue said:
Descend and maintain means descend and maintain, which means FPA (FLCH).

Descend via means path.
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"Kinda".

If you're in the flight levels, just with a basic "descend and maintain XXX" an "OP DES" (FLCH) will often dive for the weeds at idle power. Most will use "Managed" but some people are sporty and like to screw with "V/S" and all the inherent fun involved with that decision.
 
Derg said:
"Kinda".

If you're in the flight levels, just with a basic "descend and maintain XXX" an "OP DES" (FLCH) will often dive for the weeds at idle power. Most will use "Managed" but some people are sporty and like to screw with "V/S" and all the inherent fun involved with that decision.
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True. We can get what you would call a managed descent within some miles of TOD (I forget how many, honestly--I'll look) by putting a lower altitude in the window and hitting descend now in the flight plan, and activating too. It'll drive at 1000 ft/min and then intercept the path. Nifty.

I don't mess with VS in this thing. FPA is pretty cool.
 
Autothrust Blue said:
I don't mess with VS in this thing. FPA is pretty cool.
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Most of the too cool for operational convention first officers that try to begin the descent in V/S, descend in another mode, and then attempt to "smooth it out" transitioning back V/S at the bottom screw it up, during ALT * (ALT capture for the boeing types) and end up causing all sorts of hilarity.
 
Derg said:
Most of the too cool for operational convention first officers that try to begin the descent in V/S, descend in another mode, and then attempt to "smooth it out" transitioning back V/S at the bottom screw it up, during ALT * (ALT capture for the boeing types) and end up causing all sorts of hilarity.
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I'm unlikely to use the machine to correct the machine...
 
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