VNAV

Trever Oakes

Trever Oakes

Filing Flight Plan
Joined
Jul 10, 2019
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KimJongUncle
Why do pilots use VNAV less during approach than they do during other phases of flight?
 
Not sure that is correct; 90% of any one flight is in level cruise where vnav autopilot control is not relevant.
So if you were to evaluate a time study of vnav use, most of the actual vnav autopilot control usage is on climb-out or descent/approach.
 
It's a great tool for managing descent profiles.. I love it and use it as often as I can
 
I'm trying to understand Trevor's question. What "VNAV" and why does he think it's not much used on approach? If he's talking about GPS assisted vertical navigation, approach is just about the only time I use it. If he's just talking about other vertical navigation, it's used any time I have to change altitude (whether it's just watching the altimeter and vertical speed gauge or using the VS mode on my autopilot).
 
To clarify, I have this question on a homework sheet for a Human Factors class. It’s worded exactly as above though.
 
I think you need some context for your homework question.. that's a somewhat random (and I'm not even sure factually accurate) statement when it just stands alone.. if however it proceeds a chapter about vertical path management, then maybe there's a relevant answer in there for you that pertains to whatever other coursework you have that puts it in context

On another note.. I probably shouldn't get involved, but what the hell.. PoA is a great forum and indeed for people to learn (and contribute!), but we're also a community, unlike what you might find on some other sites.. looking at your posts it seems like you came here primarily to look for answers to homework questions without much introduction or otherwise participation in the community.. if you peruse our threads you'll get a sense for what I'm talking about.. maybe start a discussion instead?

You may get a different response with a different approach.. just my $0.02
 
Tantalum said:
I think you need some context for your homework question.. that's a somewhat random (and I'm not even sure factually accurate) statement when it just stands alone.. if however it proceeds a chapter about vertical path management, then maybe there's a relevant answer in there for you that pertains to whatever other coursework you have that puts it in context

On another note.. I probably shouldn't get involved, but what the hell.. PoA is a great forum and indeed for people to learn (and contribute!), but we're also a community, unlike what you might find on some other sites.. looking at your posts it seems like you came here primarily to look for answers to homework questions without much introduction or otherwise participation in the community.. if you peruse our threads you'll get a sense for what I'm talking about.. maybe start a discussion instead?

You may get a different response with a different approach.. just my $0.02
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I agree, PoA is a great site. I’ve learned a lot of things here. There isn’t enough time to ask instructors everything, and there’s some very smart people here. However, when people start saying things like above, at that point all it does is discourage people from wanting to learn. I’ll gladly take constructive answers, and I’ll take anything I can use, but I get nothing out of comments like the one mentioned. For my purposes, it really did no harm. But it makes me feel sorry for the students on here asking questions that are actually important and receiving answers like that.
 
Trever Oakes said:
I agree, PoA is a great site. I’ve learned a lot of things here. There isn’t enough time to ask instructors everything, and there’s some very smart people here. However, when people start saying things like above, at that point all it does is discourage people from wanting to learn. I’ll gladly take constructive answers, and I’ll take anything I can use, but I get nothing out of comments like the one mentioned. For my purposes, it really did no harm. But it makes me feel sorry for the students on here asking questions that are actually important and receiving answers like that.
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Trevor there are all types in this community and in the world. Even good people act like Richard Craniums sometimes, myself included. My suggestion is to use comments like the one you didn't like as motivation to finish your degree rather than react to it. Don't let the downers get you down.
 
Trever Oakes said:
Why do pilots use VNAV less during approach than they do during other phases of flight?
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Is there more context to the question? Like are you discussing autopilots, instrument flight rules?? My first instinct is I don't use "VNAV" during approach because I have vertical guidance from the ILS but that too can be considered VNAV. Or maybe they want to hear that you should hand fly from the final approach fix and not use the VNAV feature of the autopilot... Too many ways it can be construed.
 
Trever Oakes said:
Wow... That is in absolutely no way helpful to me whatsoever. Sit down and give your mind a rest.
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Well, that's the first intelligent thing you've said today. It's hard to go beyond my original answer because you've refused to answer the question I and other's put to you about some context as to what you're talking about.

The key is that I think your instructor wanted you to do something other than just ask an internet forum to give you the answer. My previous comment and the first line above come from the book (and later movie) The Paper Chase about the first year at Harvard Law School. I'll excuse you not knowing that because they came out a couple of decades before you were born.
 
flyingron said:
Well, that's the first intelligent thing you've said today. It's hard to go beyond my original answer because you've refused to answer the question I and other's put to you about some context as to what you're talking about.

The key is that I think your instructor wanted you to do something other than just ask an internet forum to give you the answer. My previous comment and the first line above come from the book (and later movie) The Paper Chase about the first year at Harvard Law School. I'll excuse you not knowing that because they came out a couple of decades before you were born.
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Lol.. I did state the context of the question though. Scroll up to find where I said it was on a Human Factors paper, but worded exactly as I said above. That’s all I have to go off of.
When such a question with limited context and no obvious answer exists, I come to PoA because it is a great forum with a lot of useful information and smart people. I couldn’t figure it out, so why not pick the minds of other experienced people who may know? Maybe it’s just a terribly worded question that has no good answer; that’s what I’m getting from this forum.
You make a lot of assumptions for someone who knows nothing about the person who you are responding to. You assume that the first thing I did when I saw this question was not to think about it, but to post on a forum to get the answer. And you even finished off with the classic boomer intimidation tactic of citing something that was around before I was born. Come on man.. If you don’t have something to say that actually matters, why even comment?
 
Grum.Man said:
Is there more context to the question? Like are you discussing autopilots, instrument flight rules?? My first instinct is I don't use "VNAV" during approach because I have vertical guidance from the ILS but that too can be considered VNAV. Or maybe they want to hear that you should hand fly from the final approach fix and not use the VNAV feature of the autopilot... Too many ways it can be construed.
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Sadly, I wasn’t given any more context. I just wrote “not enough information” and turned it in. I’m not really sure what the professor was going for with the question. I find VNAV very useful during approach; the VNAV feature on the Garmin 430 is particularly nice to use because it gives you TOD.
 
If you don’t have something to say that actually matters, why even comment?
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You must be new here. I guess we couldn't believe that "Human Factors Class" and a vague (and apparently unfounded) single statement was all the context that was available. In fact, I doubt seriously it was and I doubt that "I need more information" is the answer your professor was looking for.
 
Trever Oakes said:
Lol.. I did state the context of the question though. Scroll up to find where I said it was on a Human Factors paper, but worded exactly as I said above. That’s all I have to go off of.
When such a question with limited context and no obvious answer exists, I come to PoA because it is a great forum with a lot of useful information and smart people. I couldn’t figure it out, so why not pick the minds of other experienced people who may know? Maybe it’s just a terribly worded question that has no good answer; that’s what I’m getting from this forum.
You make a lot of assumptions for someone who knows nothing about the person who you are responding to. You assume that the first thing I did when I saw this question was not to think about it, but to post on a forum to get the answer. And you even finished off with the classic boomer intimidation tactic of citing something that was around before I was born. Come on man.. If you don’t have something to say that actually matters, why even comment?
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Boomer??? Quit fricken crying and go ask your professor, he/she is the only one who can answer your questions.

Signed,

Another boomer
 
Tantalum said:
On another note.. I probably shouldn't get involved, but what the hell.. PoA is a great forum and indeed for people to learn (and contribute!), but we're also a community, unlike what you might find on some other sites.. looking at your posts it seems like you came here primarily to look for answers to homework questions without much introduction or otherwise participation in the community.. if you peruse our threads you'll get a sense for what I'm talking about.. maybe start a discussion instead?
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Please note this date. Ravioli agrees with Tantalum.

@flyingron - The question is at least in the training forum, so that's good, right? Would have been nice if it was preceded by "My CFI asked" or "My Professor asked" rather than just throwing out the question/assertion. But pobodys nerfect, right.

@Trever Oakes - Don't let us get you down. "There are no stupid questions." Poorly worded or left field questions, on the other hand... ;)
 
Trever Oakes said:
I agree, PoA is a great site. I’ve learned a lot of things here. There isn’t enough time to ask instructors everything, and there’s some very smart people here. However, when people start saying things like above, at that point all it does is discourage people from wanting to learn. I’ll gladly take constructive answers, and I’ll take anything I can use, but I get nothing out of comments like the one mentioned. For my purposes, it really did no harm. But it makes me feel sorry for the students on here asking questions that are actually important and receiving answers like that.
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Don't take these things so personally.. I fly a fair amount ( >100 hrs/yr) and started flying when I was 14, someone here the other day asked me if I was a pilot and told me to go back to groundschool.. it's honestly actually kind of funny.. if you've ever watched Top Gear (original with Clarkson) I liken our group to something like that

Ravioli said:
Please note this date. Ravioli agrees with Tantalum.
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Achievement unlocked!

PaulS said:
Another boomer
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OK, Boomer /s
It's funny.. in person I own the whole "Cirrus pilots aren't real pilots thing" and play it up with my local friends to the point of hyperbole.. "you fly a Cirrus, cool! How do you preflight?" -- "Dude I just make sure both wings are on and I have a bottle of Voss ready to go, hit TOGA then direct enter enter" if I were a boomer I'd do the same.. get vanity "BOOMR" plates or something
..mind you, anyone who knows me well enough (and hopefully most here) know that none of these things are true, I actually fly competently, often with the AP off:eek: and actually do a legit preflight

Grum.Man said:
I have vertical guidance from the ILS but that too can be considered VNAV
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And that's why I can't believe there isn't more context.. or the question was vague on purpose to illicit critical thinking, just like it did of us here.. maybe the prof is just looking for a competent thought out best effort answer? I agree with you by the way.. "VNAV" in the context of what the autopilot does vs hand flying an ILS could be a consideration here.. but both, strictly speaking, are "vertical navigation" .. but maybe most people don't have the "VNAV" button pressed on approach because they're getting ATC defined altitudes and then intercept an ILS on vector-to-final? I'm reaching.. but that's the only way I can make the question logically work

I digress.. off the rails we are

-this millennial has a kombucha to finish and then about 2 hrs of work to get through
 
Tantalum said:
……..
OK, Boomer /s
It's funny.. in person I own the whole "Cirrus pilots aren't real pilots thing" and play it up with my local friends to the point of hyperbole.. "you fly a Cirrus, cool! How do you preflight?" -- "Dude I just make sure both wings are on and I have a bottle of Voss ready to go, hit TOGA then direct enter enter" if I were a boomer I'd do the same.. get vanity "BOOMR" plates or something
..mind you, anyone who knows me well enough (and hopefully most here) know that none of these things are true, I actually fly competently, often with the AP off:eek: and actually do a legit preflight

……..


-this millennial has a kombucha to finish and then about 2 hrs of work to get through
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Oh no, I'm a boomer AND a Cirrus pilot, lol. I'd get a BOOMER plate but really don't want my car vandalized, I live in the Republik of Massachusetts.
 
I wonder if the context of the question is an autopilot using VNAV to fly an approach and regarding the fact that many fly ILS or LPV approaches with an autopilot.

VNAV can be used for approaches without a glide slope that an autopilot can follow. It sometimes takes a little more hands on programming as well as an understanding of what the (sometimes) different colored text with and without an underline mean. In addition, there can be a timing component as to how long before an initial checkpoint the VNAV approach can be activated, depending on the system used.
 
Or it's possible the instructor wanted the student to posit how he would determine what the statement means and suggest ways to validate the hypothesis. Getting your panties in a twist because you didn't get a canned answer from the forum and just writing "I can't tell" on the assignment is probably not what the instructor wanted to see here.
 
flyingron said:
Or it's possible the instructor wanted the student to posit how he would determine what the statement means and suggest ways to validate the hypothesis. Getting your panties in a twist because you didn't get a canned answer from the forum and just writing "I can't tell" on the assignment is probably not what the instructor wanted to see here.
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Yup...there is most likely some context to this question of which the OP is blissfully unaware.
 
PaulS said:
Oh no, I'm a boomer AND a Cirrus pilot, lol. I'd get a BOOMER plate but really don't want my car vandalized, I live in the Republik of Massachusetts.
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I'm in California.. not sure which is worse!
 
+1 to the suggestions to seek clarification directly from the professor.

I give a lot of tests and homework, and have no sympathy for those who just write "the question is confusing" and turn it in. If the intent is confusing, ya gotta ask me to clarify -- think of this as part of your job. Answering is part of my job.

You might also want to ask your professor about whether he or she considers "seeking answers on the internet" (looking them up, or soliciting them from forums) to be a form of academic dishonesty or not for this kind of assignment. In my class (physics), it generally is. But it may depend on the assignment. Tread carefully. The only way to know is to ask. Good luck!

--Professor from Gen-X


P.S. I didn't understand the intent of the VNAV question either.
 
Sounds like someone's wife is post menopause, and isn't giving it up. So he has to come on here and shake his fist at the clouds because he's tired of shaking his fist in other ways.

Sorry you were subject to that Trever. At least nothing got on you.
 
flyingron said:
Or it's possible the instructor wanted the student to posit how he would determine what the statement means and suggest ways to validate the hypothesis. Getting your panties in a twist because you didn't get a canned answer from the forum and just writing "I can't tell" on the assignment is probably not what the instructor wanted to see here.
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For someone with such a detailed template on critical thinking, I am surprised that you seem to be completely oblivious or ignorant to the tone behind this conversation.
I am okay with not finding the answer of this question; the professor is a very easy grader and I’m not going to lose a letter grade over one single question that myself and my classmates all had an issue with.
What I have an issue with is people who find threads posted by people who want to learn, and decide to post something like your second response towards the OP just to be an ass.
I personally could care less about your opinion, but there are people on this site who are actually trying to learn something, and it’s people like you who make that difficult. That is what my issue is.
 
Trever Oakes said:
For someone with such a detailed template on critical thinking, I am surprised that you seem to be completely oblivious or ignorant to the tone behind this conversation.
I am okay with not finding the answer of this question; the professor is a very easy grader and I’m not going to lose a letter grade over one single question that myself and my classmates all had an issue with.
What I have an issue with is people who find threads posted by people who want to learn, and decide to post something like your second response towards the OP just to be an ass.
I personally could care less about your opinion, but there are people on this site who are actually trying to learn something, and it’s people like you who make that difficult. That is what my issue is.
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Made even more difficult by the person “trying to learn” engaging in arguments on the internet that bear no relevance to what he’s “trying to learn”.

Welcome to the world. It’s a two-way street.
 
Trever Oakes said:
...I’m not going to lose a letter grade over one single question that myself and my classmates all had an issue with.
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Dear Lord, Please let the prof grade him down for this statement alone. It's 'my classmates and I had an issue' for Christ's sake. How many other courses are you failing?
 
Ravioli said:
Dear Lord, Please let the prof grade him down for this statement alone. It's 'my classmates and I had an issue' for Christ's sake. How many other courses are you failing?
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Haha.. I bet you’re really fun at parties.
 
Back to the question at hand - I am still a low-time private pilot, but I too find the basic VNAV calculations provided by the G430w pretty useful. I used it for the first time last weekend and it really helped to nail my TOD and resulted in a more comfortable 500fpm descent to pattern altitude and to my filed altitude penetrating the SFRA on my return. Pretty easy to either give it a ft above MSL or ft above an airport. I was pretty quickly able to program a VNAV profile to get me down to 2000' MSL 3 miles after a VOR waypoint... Anyway long story short even basic VNAV not coupled to an autopilot was pretty useful for me in terms of workload reduction... not that manually calculating a TOD is that tough.
 
Agree on the 430W VNAV thing. I will set it up for 1000AGL 2nm from destination when VFR. Had to qualify that if was for VFR, because some assbag CFI with epaulettes, or some old **** who's involuntarily celibate would chime about "terrain avoidance in rocky areas" and" you can't just descend like that always" blah blah. Can it, assbags. So to answer the original question, I use VNAV less/not at all for approach, because when IFR, I'm given altitudes by ATC, and just do the lazy 500-1000 FPM descent, and am not going to fiddle with unnecessary screen switching on the 430W when IMC. Then once on the approach proper, it's adhere the numbers on the plate, and again, unnecessary switching of the 430W screen. VFR is nice because I can shut off the brain, look outside for traffic, and I will get a MSG flashing at me to crank in a couple spins of trim for a 500fpm descent. (I like to be nice to my passengers' ears.)
 
VNAV is great on approaches as when set correctly it will do the stepdowns for you (Perspective). Good stuff if you remember to use it.
 
PaulS said:
VNAV is great on approaches as when set correctly it will do the stepdowns for you (Perspective). Good stuff if you remember to use it.
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It's real functionality is for those IFR crossing restrictions, but it's good for so much more. The problem for some IFR pilots is, the function (which exists in most current units, and is relatively rudimentary in the GNS) is used to little, that when they need it, they're not sure what to do. It's not a bad idea to use it regularly, even VFR like @Deelee, just to get into the habit and have the methodology fixed.
 
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