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Luftfahrer
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What Kind Of Approach Is That? [Video Enclosed]

Wed Jul 29, 2015 1:32 pm

Hello all,

please refer to the following video:

https://www.youtube.com/watch?v=lSQ2IIaGdXs

This is a Boeing 73G on arrival to runway 03R at Tocumen airport in Panama City (PTY/MPTO).

As you can see the pilots have both the LOC and VNAV mode activated for most of the final approach. I can't remember ever having seen this combination before. I checked the available procedures (which may have changed in the meantime) and available approach types to that runway include both ILS and RNAV/GPS (as well as SRA).

So I am wondering: Is this primarily an ILS (or rather, LOC) approach with VNAV instead of GS for vertical guidance (possibly due to GS inop)? Or an RNAV approach with LOC activated instead of LNAV for better lateral guidance? Or something completely different? Thank you for any insight.  Smile

[Edited 2015-07-29 06:40:31]
 
rendezvous
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Jul 29, 2015 9:12 pm

Maybe a LOC/DME approach using VNAV guidance to make it easier than using and adjusting VS the whole way.
 
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Starlionblue
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Jul 29, 2015 9:38 pm

YouTube links work if you remove the "s" in "https"

http://www.youtube.com/watch?v=lSQ2IIaGdXs
 
Luftfahrer
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Jul 29, 2015 10:25 pm

Quoting Starlionblue (Reply 2):
YouTube links work if you remove the "s" in "https"

Thanks! Even after six years of membership, I still don't know all the quirks of this forum. 
Quoting rendezvous (Reply 1):
Maybe a LOC/DME approach using VNAV guidance to make it easier than using and adjusting VS the whole way.

Yes, this is what I'm leaning towards as well. On the FMC in the video you can see they did select the ILS approach and the corresponding waypoint LAMBI can also be seen on the ND. My best guess is the glideslope was inoperative and so they simply used the VNAV mode to control the descent. However as they get closer to the runway, VNAV is also disconnected, though not sure if manually or automatically.

A true RNAV approach:

View Large View Medium
Click here for bigger photo!

Photo © zazaboeing



[Edited 2015-07-29 15:29:38]
 
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barney captain
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RE: What Kind Of Approach Is That? [Video Enclosed]

Thu Jul 30, 2015 7:47 am

Certain operators have tailored approaches that utilize LOC for lateral guidance and VNAV for vertical on non-precision approaches. This will become more standard as time goes on to eliminate the "dive and drive" of some NP approaches.
 
Max Q
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RE: What Kind Of Approach Is That? [Video Enclosed]

Sat Aug 01, 2015 9:07 am

Barney, do you still do dive and drive on some non precisions ?


We don't do that at all anymore.
 
thegman
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RE: What Kind Of Approach Is That? [Video Enclosed]

Sat Aug 01, 2015 9:40 pm

Quoting Max Q (Reply 5):

Barney, do you still do dive and drive on some non precisions ?


We don't do that at all anymore.

In Barney dive and drive is used for non-precision.
 
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barney captain
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RE: What Kind Of Approach Is That? [Video Enclosed]

Mon Aug 03, 2015 9:36 am

Quoting Max Q (Reply 5):
Barney, do you still do dive and drive on some non precisions ?

No. In the NG fleet, we use LNAV and VNAV on RNAV or GPS approaches. In the classic fleet with a non-prec app, we're limited due to the lack of a moving map. So no RNAV or GPS approaches in the classics. So on a LOC only app, we use a constant rate descent using VS method which closely approximates what the VNAV would follow.

Quoting thegman (Reply 6):
In Barney dive and drive is used for non-precision.

Huh?
 
BravoOne
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RE: What Kind Of Approach Is That? [Video Enclosed]

Mon Aug 03, 2015 2:05 pm

This may be a IAN approach (Integrated Approach Navigation) assuming the operator has approval along having purchased this optional capability from Boeing
 
thegman
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RE: What Kind Of Approach Is That? [Video Enclosed]

Mon Aug 03, 2015 5:25 pm

Quoting barney captain (Reply 7):

Huh?

The C-17.
 
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barney captain
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RE: What Kind Of Approach Is That? [Video Enclosed]

Tue Aug 04, 2015 7:26 am

I think I figured out where you were going with this -

Is the C-17 referred to as "Barney"?
 
Max Q
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RE: What Kind Of Approach Is That? [Video Enclosed]

Tue Aug 04, 2015 10:51 am

Quoting barney captain (Reply 7):
No. In the NG fleet, we use LNAV and VNAV on RNAV or GPS approaches. In the classic fleet with a non-prec app, we're limited due to the lack of a moving map. So no RNAV or GPS approaches in the classics. So on a LOC only app, we use a constant rate descent using VS method which closely approximates what the VNAV would follow.

Understood.


Ten times your groundspeed divided by two works well for a VS in the absence of VNAV.
 
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barney captain
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RE: What Kind Of Approach Is That? [Video Enclosed]

Tue Aug 04, 2015 8:50 pm

Quoting Max Q (Reply 11):
Ten times your groundspeed divided by two works well for a VS in the absence of VNAV.

That works beautifully for sure. We actually "cheat" by referencing the vertical deviation on the MCDU and adjust VS as necessary. You can usually hold it within +/- 30 ft without any trouble (usually less). For these non-prec app, we compute a DDA (Derived Decision Alt) by adding 50' to the MDA. This allows for a for a GA without descending below the actual MDA.

The reality is, we do so few of these type of approaches, that it's rarely an issue. The only exception is SAN, where it's the norm.
 
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flylku
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Aug 05, 2015 1:46 am

Quoting Max Q (Reply 11):
Ten times your groundspeed divided by two works well for a VS in the absence of VNAV.

I'd never heard that before but sure enough, in my humble little bird, 10 X 90kts = 900 dived by 2 = 450 which is exactly what I normally find maintains the GS on an ILS.
 
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Starlionblue
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Aug 05, 2015 3:15 am

Quoting flylku (Reply 13):

Quoting Max Q (Reply 11):
Ten times your groundspeed divided by two works well for a VS in the absence of VNAV.

I'd never heard that before but sure enough, in my humble little bird, 10 X 90kts = 900 dived by 2 = 450 which is exactly what I normally find maintains the GS on an ILS.

I learned 5x groundspeed while doing my PPL, which of course is "times 10 divided by 2".

In initial airliner training I was told to forget that and go with "half your groundspeed". Thus GS 150 gives V/S of 750fpm. Same result but perhaps slightly easier maths.
 
Max Q
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Aug 05, 2015 5:20 am

Quoting barney captain (Reply 12):
That works beautifully for sure. We actually "cheat" by referencing the vertical deviation on the MCDU and adjust VS as necessary. You can usually hold it within +/- 30 ft without any trouble (usually less).

That's on your non NG's ?


I can see how that would work very well.

Quoting barney captain (Reply 12):
For these non-prec app, we compute a DDA (Derived Decision Alt) by adding 50' to the MDA. This allows for a for a GA without descending below the actual MDA.

That's exactly the same as our procedure.


I sure don't miss the old 'dive and drive' days. Flying every approach in a stabilized, precision manner is a major improvement in safety.


I've gone into SAN a few times with this procedure and it works very well, as you say it's very rare to see it elsewhere, other than the Sim.

Best wishes.

[Edited 2015-08-04 22:22:35]
 
Max Q
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Aug 05, 2015 5:27 am

Quoting Starlionblue (Reply 14):
I learned 5x groundspeed while doing my PPL, which of course is "times 10 divided by 2".

That's good.

Quoting Starlionblue (Reply 14):
n initial airliner training I was told to forget that and go with "half your groundspeed". Thus GS 150 gives V/S of 750fpm. Same result but perhaps slightly easier maths.

Isn't that half your groundspeed times ten ?


Half of 150 being 75 ?!


Seems like there's a few good techniques


I do like easier calculations myself !


Best wishes.

[Edited 2015-08-04 22:28:42]
 
Max Q
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Aug 05, 2015 5:29 am

Quoting flylku (Reply 13):
I'd never heard that before but sure enough, in my humble little bird, 10 X 90kts = 900 dived by 2 = 450 which is exactly what I normally find maintains the GS on an ILS.

What are you aviating in flyk ?
 
thegman
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Aug 05, 2015 5:55 am

Quoting barney captain (Reply 10):

I think I figured out where you were going with this -

Is the C-17 referred to as "Barney"?

Mostly by C-5 people/lovers. Due to the nickname of the C-5, FRED. Barney is FRED's smaller sidekick, a nod to the Flintstones.

I thought your name was in reference to that.
 
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Starlionblue
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Aug 05, 2015 6:03 am

Quoting Max Q (Reply 16):

Quoting Starlionblue (Reply 14):
I learned 5x groundspeed while doing my PPL, which of course is "times 10 divided by 2".

That's good.

Quoting Starlionblue (Reply 14):
n initial airliner training I was told to forget that and go with "half your groundspeed". Thus GS 150 gives V/S of 750fpm. Same result but perhaps slightly easier maths.

Isn't that half your groundspeed times ten ?


Half of 150 being 75 ?!


Seems like there's a few good techniques


I do like easier calculations myself !

Yep, they're all the same. It has been interesting to see how people from different countries and backgrounds teach some of these basic things differently, and of course only their method is "the right one". 
 
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flylku
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RE: What Kind Of Approach Is That? [Video Enclosed]

Wed Aug 05, 2015 1:17 pm

Quoting Max Q (Reply 17):
What are you aviating in flyk ?

A Piper Warrior with the 160. Today I am flying a Searay (amphibian) with an instructor. Later this year I will fly a sailplane again. After that I will decide what rating to get next: always looking for ways to become a better pilot.
 
Max Q
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RE: What Kind Of Approach Is That? [Video Enclosed]

Thu Aug 06, 2015 5:37 am

Quoting flylku (Reply 20):
A Piper Warrior with the 160. Today I am flying a Searay (amphibian) with an instructor. Later this year I will fly a sailplane again. After that I will decide what rating to get next: always looking for ways to become a better pilot.

Very nice, the Warrior is a nice flying aircraft and that Searay looks like a blast.'


Best wishes.
 
Max Q
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RE: What Kind Of Approach Is That? [Video Enclosed]

Thu Aug 06, 2015 5:40 am

Quoting Starlionblue (Reply 19):
Yep, they're all the same. It has been interesting to see how people from different countries and backgrounds teach some of these basic things differently, and of course only their method is "the right one".

Good point and I agree, many different techniques out there, all that really matters is that it works and simple is better.
I've always been a big fan of the 'rule of thumb'


I never stop learning.


Best wishes.
 
AAR90
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RE: What Kind Of Approach Is That? [Video Enclosed]

Thu Aug 06, 2015 2:17 pm

Quoting barney captain (Reply 12):
The reality is, we do so few of these type of approaches, that it's rarely an issue. The only exception is SAN, where it's the norm.

Which begs the question: why do so many WN flights specifically request the RNAV-27 approach to SAN when the LOC-27 has lower minimums? Some procedural requirement(s) at WN?

Reason for asking is at AA the procedures are the same (use LNAV/VNAV) and as long as the LOC course is displayed I can use the LOC-27's lower minimums. I've landed 3 times this past winter when others (flying RNAV 27) have had to go around.
 
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barney captain
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RE: What Kind Of Approach Is That? [Video Enclosed]

Fri Aug 07, 2015 11:59 pm

Quoting Max Q (Reply 15):
That's on your non NG's ?

No, sorry - I wasn't clear. That "trick" is used in the classics where we can't use VNAV inside the FAF.

Quoting thegman (Reply 18):
I thought your name was in reference to that.

Ah, I see! I never knew that and I fly with quite a few C5 pilots. No, the name is (was) in reference to the Canyon Blue (purple) on the outside of our a/c and it's resemblance to a particular childrens dinosaur. I suppose I could update it for the new livery, but something about "Hot Dog on a Stick Captain" just sounds, well, wrong.  
Quoting AAR90 (Reply 23):
Which begs the question: why do so many WN flights specifically request the RNAV-27 approach to SAN when the LOC-27 has lower minimums? Some procedural requirement(s) at WN?

Reason for asking is at AA the procedures are the same (use LNAV/VNAV) and as long as the LOC course is displayed I can use the LOC-27's lower minimums. I've landed 3 times this past winter when others (flying RNAV 27) have had to go around.

Unfortunately we can't use the LOC overlay to get the lower mins, so it's the RNAV for ease of use unless we need the LOC for the lower mins. Completely backward imo that the higher workload LOC app gets us lower mins than the RNAV, but that's the way it works out with the DDA. Maybe one day we'll catch up. Hope all is well AAR.

[Edited 2015-08-07 17:00:11]
 
Max Q
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RE: What Kind Of Approach Is That? [Video Enclosed]

Sat Aug 08, 2015 4:43 am

Quoting barney captain (Reply 24):
Quoting Max Q (Reply 15):
That's on your non NG's ?

No, sorry - I wasn't clear. That "trick" is used in the classics where we can't use VNAV inside the FAF.

Understood, that's what I meant !


Best wishes
 
Luftfahrer
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RE: What Kind Of Approach Is That? [Video Enclosed]

Mon Aug 10, 2015 7:30 am

Quoting Starlionblue (Reply 14):
I learned 5x groundspeed while doing my PPL, which of course is "times 10 divided by 2".

Tell me your method and I tell you how good you're at mental arithmetic... 
 
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Starlionblue
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RE: What Kind Of Approach Is That? [Video Enclosed]

Mon Aug 10, 2015 7:39 am

Quoting Luftfahrer (Reply 26):

Quoting Starlionblue (Reply 14):
I learned 5x groundspeed while doing my PPL, which of course is "times 10 divided by 2".

Tell me your method and I tell you how good you're at mental arithmetic... 

Ha! 5x groundspeed is pretty easy in a 172. Harder in a jet given the speeds (what's 5 x 143?). ½ groundspeed suddenly becomes way easier.  

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