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Old 7th Jan 2017, 01:17   #1 (permalink)
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B737NG Vor Approach

Which mode is best, LNAV or VOR/LOC?

Advantages and disadvantages.

Assuming nav aid at the end of the arrival runway.

Thank you.
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Old 7th Jan 2017, 04:02   #2 (permalink)
 
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Approach mode, what else? Backup is LNAV/VNAV for that.
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Old 7th Jan 2017, 04:29   #3 (permalink)
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NPA - talking lateral sense now.
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Old 7th Jan 2017, 06:54   #4 (permalink)
 
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Yes, so was i. Approach mode takes care of both lateral and vertical of course. And is the preferred mode of operation.
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Old 10th Jan 2017, 21:45   #5 (permalink)
 
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Not a lot of operators are approached for IAN approaches.
Raw data navigation tracking will be more accurate. When flying in LNAV you can parallel the actual required radial which is one of the down falls.
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Old 11th Jan 2017, 14:47   #6 (permalink)
 
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There is special approval required for IAN? Wasn't aware of that, and as far as i know IAN is standard equipment from a certain MSN on.

Anyway, i would argue that LNAV is actually much more precise than raw data, a standard VOR can be up to several degrees off, a DVOR still up to 1, plus up to 0.4 receiver error added to that, whereas ANP with the 737NG is usually around 0.05. However, yes, coding of the VOR approach in the database has to be correct of course, something which should be taken care of by the database supplier and the quality management system of the airline.

VOR/LOC could be used, however only if there is a co-located DME with the VOR and the VOR is situated below 5000ft, at least according to the FCOM i have, but is really meant for approaches where the VOR is on the arrival end of the runway or well in front of it.
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Old 11th Jan 2017, 15:48   #7 (permalink)
 
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Denti - My airline would have kittens if I did an IAN approach. We only just got approved for RNAV approaches and still people are sceptical of doing them.

VOR/LOC and VS is in the DNA.
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Old 11th Jan 2017, 17:16   #8 (permalink)
 
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There is special approval required for IAN? Wasn't aware of that, and as far as i know IAN is standard equipment from a certain MSN on.
Unfortunately no, still optional...

I'd say if you have dual GPS, good ANP and coded approach, LNAV/VNAV (or IAN if you're lucky) is the way to go. Makes it much easier and you can still monitor the needles/DME on ND.
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Old 11th Jan 2017, 20:26   #9 (permalink)
 
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VOR/LOC and VS is in the DNA
Oh my, that is something i had to do in initial training on the -300 all those years ago, and even then we changed it to LNAV/VS very soon on the classic, on the NG with its much better avionic suite it was LNAV/VNAV until IAN arrived in, hmm, 2005 or so.
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Old 11th Jan 2017, 21:31   #10 (permalink)
 
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1 IAN
2 LNAV/VNAV
3 LNAV/VS
4 VORLOC/VS
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