Real life 737 NG - RNAV question

[Guest Lenny Zaman]

Chris An RNAV approach will be considered as a non precision approach.Not sure about the boeing procedure but i think you are confusing with an airbus procedure.Normally approaching the final stage of the approach(usually for non precisions we fly in 'managed-selected' or 'managed-managed'(horiz mode-vert mode)) Flying a fully managed RNAV approach(which requires a high NAV ACCURACY and GPS primary) requires the pushing of the airbus 'APPR' button on the FCU. This will arm the FINAL APP mode. Which basically is a nicely enhanced NAV mode and virtual (FMGS calculated) Glide Slope(using the "brick" as reference), but not using any navigation signal apart from the GPS enhanced FM mixing position.Basically, if you fly an RNAV approach fully managed in an airbus, you will push the APPR button before passing the FAF and you will get very similar indications as the ILS.(the 'Brick' glideslope)In boeing, the only logic option for me to perform an RNAV approach is VNAV+LNAV coupled and pretty high minima.(as well as GPS primary etc etc).Bottomline:Don't mix up the 2 concepts,in boeing planes,the 'APP' pushbutton is only for ILS approaches(maybe MLS in some customised planes/facilities) but NOT for RNAVIn airbuses the APPR button is also used in non precision approaches.Hope this helps a bit...and hope the explanation is not too confusingCheers

[basa 0]

Talking about RNAV approaches, look at this: It seems a RNAV approach, VNAV and LNAV engaged in short final.Jose Luishttp://www.airliners.net/open.file/1067620/L/

[neilbradley1 2]

Clayton,The chart you have displayed is a STAR (STandard Arrival Route) designed to get the aircraft in a position at to either execute a VSA (visual approach) to RWY 01 via STAKE and the Visual River Track, or to carry out the VOR RWY 14 approachas stated in the narrative.Niether of these are RNAV approaches to a runway as I think you believe they are. In Australia they are called RNAV (GNSS) approaches and are basically GPS approaches requiring no ground aid input (VOR or NDB). Brisbane (YBBN) has four such approaches published. The one for RWY 01 starts at GLENN at 3000', course 016. At 5.6 NM to BBNSF commence descent to cross 4.0 NM BN at 2505'. Cross BBNSF at 1230'. Descend to the MDA (560' for straight in)and track to BBNSM. If not visual at BBNSM carry the missed approach. Track direct to BBNSH, thence 016 or as directed by ATC. Climb to 3000'.Hope that helps.NB

[Guest tomahawk_pa38]

Chris,Maybe you've tried this and I apologise in advance if I'm insulting your intelligence, but I had a spell of this happening and it was always on flights over about an hour long. Solution (as supplied by Matts some while ago) : Apparently if you don't make sure your power supply settings are correct on the overhead, the batteries run down and the first thing you lose is the nav stuff. So make sure you have no blue lights illiminated on the overhead - this cured it for me.

[Tabs 2,790]

Clayton,That chart is a STAR, not an approach - the reason you were able to use LOC and GS modes on it is because you're intercepting an ILS at the end there... An actual RNAV approach such as this one: http://www.myairplane.com/databases/approa...fs/00430R21.PDF here at my home airport, has no reference to a localizer frequency etc. You simply fly it in LNAV and VNAV down to the minimum descent altitude, which in this case is 3160 without VNAV (ie, if you're just stepping down in FLCH or VS) and 3080 if you have VNAV engaged. If you can't see the runway upon reaching that altitude, you execute a missed approach and either try again or switch to a precision approach with lower minimums...

[Chris Catalano 0]

Thanks for the thought. Actually, it was not that as it turned out. I DID try arming VNAV & typed in the speed & altitude constraints & the worked like a CHARM!!!!! Pressing the APPR button in the boeing planes will not work to couple the systems. This only works in the Airbus planes as stated above. I got it also on good authority from a dear friend of mine who is a real-life Captain of an A320. He used to fly the Boeing 737 & said that pressing approach in the Boeing planes for an RNAV will not bring you down the glideslope as it does in the Airbus planes. Again, I tried typing in speed & altitude constraints with VNAV engaged & it worked fine. I also made sure that I had VREF + 5 set as the speed for the FAF. I actually decided to hand dial the speeds down to the appropriate values until I got to 1 mile before the FAF, and then, when the plane was at the correct speed & altitude, I pressed VNAV & the plane flew perfectly down the glideslope in this non-precision approach. Thanks to all of you for helping me to figure this out.Chris Catalano

[clayton4115 56]

hi Ryan and Neilthanks for this information,Ryan, for the rnav at your airport do those waypoints actually go into the FMC?