What Heavy jet will SWA buy?

[jynxyjericho]

So, you're a quitter? Couldn't handle it on the Surge 9? You work at Wendy's now? Thought so. Good try anyway... Have you thought about being a Legacy FA? If so, when you have a chance, can I get a Coke? And Jynxy, make it a Diet....


Bye Bye---General Lee

Lol. Pepsi ginny, no Coke!

 

[redflyer65]

The General hijacking a thread from St. George? Of course, it's a SW thread.

What an idiot. Gives the actual Delta pilots a bad name.

 

[Jim]

Could you give us an example of the "I had no idea..."?

If you're talking about discussing VNAV with the SWA pilots I know in Vegas, then it's normally things like when you can use speed intervention and remain in VNAV Path, at what speed difference will it drop into VNAV Speed from VNAV Path (i.e set speed versus what is actual as plane tries to maintain path), why you don't want to change "at or above" altitudes to hard altitudes, what "descend now" does with regard to computed path, etc.

But I'm out because obviously SWA pilots know everything about everything and the rest of us idiots use speed brakes because we're too stupid to figure it out (not talking about your posts per se). It's not a discussion anymore.

 

[General Lee]

Lol. Pepsi ginny, no Coke!

Not at my airline. You will need to know that as a new FA here....


Bye Bye---General Lee

 

[waveflyer]

If you're talking about discussing VNAV with the SWA pilots I know in Vegas, then it's normally things like when you can use speed intervention and remain in VNAV Path, at what speed difference will it drop into VNAV Speed from VNAV Path (i.e set speed versus what is actual as plane tries to maintain path), why you don't want to change "at or above" altitudes to hard altitudes, what "descend now" does with regard to computed path, etc.

But I'm out because obviously SWA pilots know everything about everything and the rest of us idiots use speed brakes because we're too stupid to figure it out (not talking about your posts per se). It's not a discussion anymore.

If you ignore GL and the other trolls, it can still be a useful discussion-
I am no self proclaimed expert Jim- and we're all too aware of those that don't have a great understanding of vnav. And rnp. And rnav. And lnav. And autothrottles. And iPads. And EFB's. And the -800 radar. And HF. And intl.

The list goes on my man-
This historically has not been a company that has embraced technology. IMO, GK is trying to change that and is meeting criticism from senior line folks from just about every department. He has stressed it- we have to use the latest in technology -

But to that end-
Our understanding is that not all boeing vnav operates exactly the same, and there is much difference within the internal guts of boeings top of the line vnav vs ours which is essentially one of the cheapest.
Is this rumor to you or how you understand it as well?
We have been taught when speed intervention can be used and remain in path- on approach essentially on an rnp -
And speed difference it will drop into vnav speed vs path-
I'm not all that studied up, just a dumb FO with a dozen competing interests- but I do want to understand this-
My understanding is that VNAV doesnt attempt to maintain a speed on an idle descent unless it drops 15 it's slow and the AT wakes up
It calculates a path based on that speed and then flies that path- and it is a deviation from that path by X amount, that constantly changes vs computer perceived, programmed and actual reality, which will recalculate paths and revert to vnav speed once outside it's parameters.

The last two are pretty simple and I'll acknowledge that there are quite a few who fumble a bit still-

But set me straight on the one above-

More specifically, if like to know if Boeing does in fact produce several levels of vnav that operate similarly with different levels of performance

 

[Golden Falcon]

My understanding is that VNAV doesnt attempt to maintain a speed on an idle descent unless it drops 15 it's slow and the AT wakes up
It calculates a path based on that speed and then flies that path- and it is a deviation from that path by X amount, that constantly changes vs computer perceived, programmed and actual reality, which will recalculate paths and revert to vnav speed once outside it's parameters.

Vnav will calculate a flight idle descent path based on the speed entered by the crew, weight of the airplane, and wind forecast entered by the crew, and any applicable speed constraints, the most common cause of speed deviations was the actual wind being different than the forecast entered by the crew, VNAV mode will activate the A/T when the speed is <15kts is correct, at least on the Boeing models I have flown..

 

[wood pecker]

Deleted rant

 

[Monkey Face]

More specifically, if like to know if Boeing does in fact produce several levels of vnav that operate similarly with different levels of performance

I believe there are two versions of common V-nav, full geometric path and partial geometric path. Southwest uses partial. When using partial, it may have a slight economy advantage. I was told one can change from full to partial with changes made on the CDU/MX prompt.

 

[Jim]

If you ignore GL and the other trolls, it can still be a useful discussion-
I am no self proclaimed expert Jim- and we're all too aware of those that don't have a great understanding of vnav. And rnp. And rnav. And lnav. And autothrottles. And iPads. And EFB's. And the -800 radar. And HF. And intl.

The list goes on my man-
This historically has not been a company that has embraced technology. IMO, GK is trying to change that and is meeting criticism from senior line folks from just about every department. He has stressed it- we have to use the latest in technology -

But to that end-
Our understanding is that not all boeing vnav operates exactly the same, and there is much difference within the internal guts of boeings top of the line vnav vs ours which is essentially one of the cheapest.
Is this rumor to you or how you understand it as well?
We have been taught when speed intervention can be used and remain in path- on approach essentially on an rnp -
And speed difference it will drop into vnav speed vs path-
I'm not all that studied up, just a dumb FO with a dozen competing interests- but I do want to understand this-
My understanding is that VNAV doesnt attempt to maintain a speed on an idle descent unless it drops 15 it's slow and the AT wakes up
It calculates a path based on that speed and then flies that path- and it is a deviation from that path by X amount, that constantly changes vs computer perceived, programmed and actual reality, which will recalculate paths and revert to vnav speed once outside it's parameters.

The last two are pretty simple and I'll acknowledge that there are quite a few who fumble a bit still-

But set me straight on the one above-

More specifically, if like to know if Boeing does in fact produce several levels of vnav that operate similarly with different levels of performance

In this case it more SWA Bubba than General Lee...

I've been told by Boeing instructors that the principals of VNAV are the same, how you implement/program VNAV differs by FMS/aircraft. But

- VNAV attempts to maintain optimum glide path. It will allow speed increases of up to +/- 15 KIAS to do so. Once the speed is greater than +/- from programmed, it drops out of path into speed.

- If you get the "drag required" FMS message, optimum glide path can not be maintained within the +/-15 KIAS speed constraint. You have to add drag to remain on path either through the use of flaps, speed brakes (or landing gear...) or a combination these. This is where , in my opinion, the SWA no speed brakes with flaps rule becomes a problem. Say you are doing an arrival with both speed and altitude restrictions and to fly that speed you need flaps to be above a minimum maneuvering speed. You get the add drag message. If you don't add drag, you do not descend at a rate great enough to maintain the path (next altitude restriction). Your speed requires flaps and is often above the next flap speed so more flaps are not an option. Now it is speed brakes or landing gear if you want to continue using a VNAV decent. I've seen SWA drop their gear 40 miles out of Vegas because of this. Talk about noise/vibration/pax comfort.... Of course you can always quit using a VNAV decent mode but then you lose all the advantages - mainly being if you keep the plane in VNAV Path you will meet all the arrival speed and altitude constraints of the published arrival (assuming you set up your FMS right).

- If you are not speed restricted, you can increase your speed on the VNAV descent page instead of adding drag if a greater descent rate is needed to meet an altitude restriction.

- Unless you are in the "on approach" mode, any speed intervention will drop it out of path and into speed mode. The approach phase is normally within about 12 miles or so of landing but it varies with each approach. You can determine if you are in the approach phase via your FMS. This varies with the FMS for example with the 767 Pegasus FMS we can tell on the route page. Worst case, always change your speed on the FMS VNAV descent page until right before the FAF (within 12 miles of the field) instead of using speed intervention.

- To maintain VNAV Path, make sure all your speed and altitude constraints are programed into your FMS. Unless a hard altitude is required, an "at or above" altitude usually works best because this allows the FMS to compute an optimum constant descent angle while meeting the final hard altitude requirement. If you want to slow or are given an assigned speed by ATC, change the speed on the VNAV descent page so the FMS can recompute a new path based on that speed.

- If you use "descend now", VNAV will initially set up a less than optimum slower descent rate until it intercepts the optimum glide path at which time it will increase the rate. If ATC gives you an early decent, use descend now vice flight level change if you plan on using a VNAV descent.

- Any use of the vertical speed mode will take you out of VNAV path.

Edit:

Vnav will calculate a flight idle descent path based on the speed entered by the crew, weight of the airplane, and wind forecast entered by the crew, and any applicable speed constraints, the most common cause of speed deviations was the actual wind being different than the forecast entered by the crew, VNAV mode will activate the A/T when the speed is <15kts is correct, at least on the Boeing models I have flown..

This too. If you think you will have stronger tail winds than predicted, you can trick the system by telling it engine anti-ice on. VNAV will then calculate its path using a higher idle thrust.

2nd Edit:
Speed brakes are not an "idiot stick" for use only when you screw up or when ATC screws you up. Speed brakes are a necessary tool for VNAV and should be used when needed without "shame".

 

[BILL LUMBERG]

Well done Jim.