B737NG FMS and NDB Approach

[GAFA]

Does the B737NG FMS database contain NDB approach's? If it doesn't can you build the approach? I believe the A320 and F100/F70 FMS allows you to build the approach by selecting procedure turn and then entering the required data. Can this be done in the B737NG?

[Rainboe]

What is in the FMS database is what modules for the database your airline has purchased as an option. Yes you can put in NDB approaches, but you must still set up the equipment so one pilot flies the approach 100% and the other pilot usually monitors the map picture.

[Ennie]

We have NDB approaches in our 737 PG & NG FMS's.
We fly them in LNAV and VNAV together and if programmed properly the Autopilot does an excellent job!

[RAT 5]

You can build whatever you wish for approach, except manoeuvres like procedure turns, DME arcs etc. These can be approximated using suitable radial/distances.
If there is a VOR or even ILS approach in the FMC, which mirrors the NDB profile it is acceptable to use this. If you construct an approach you would most likely not be allowed to use LNAV, but HDG SEL and monitor raw data. You should monitor raw data at all times anyway.

[GAFA]

Thanks for the replies.

Would you build the NDB approach in the FIX page?

[Rainboe]

I think you should only set up a simple elementary approach using the FIX page and LEGS page (if you must do that). Do all the rest on Heading Mode and flying the aeroplane using the autopilot in Heading and using radio inputs rather than going head down for 5 minutes setting up procedure turns/altitudes/speeds and trying to fly a procedure in LNav. FMS is not a new way of doing things, just an enhancement and aid in your current way of flying. It is still not to be implicitly trusted and relied on.

[Capn Bloggs]

Using non-database approaches below the MSA is illegal here.

Rainboe :D

[Rainboe]

Quite! But where's 'here'? It's a question of philosophy. You are NOT setting up a non-database approach. You are merely setting up track lines and a fix position that approimates with what you think you will want to fly. Then you leave it alone- it's you, the NDB needles, a compass and a stopwatch. If you try and fly this in NAV, you would be demented! But you should have the track lines there for the guidance of the non-handling pilot.

[BOAC]

I assume the original poster's intention was to use LNAV/VNAV for the approach?

It will come, and there is no reason not to do it when company/regulatory rules allow. BA are already flying RNAV approaches into LGW on the Classic 737 on, I believe, a trial basis.

I guess with the growing inability of new co-pilots to navigate WITHOUT the map screen, building an NDB approach would make sense in a monitoring sense - as long as it is flown 'NDB needles' where company rules insist. I cannot see it being permissable, however, as a primary approach aid UNLESS the above permission is in place AND the non-procedural approach is in the company database.

[captjns]

As with most companies I have been with, if there is no overlay approach associated with the "pure" NDB approach which may not not be contained within the FMC's data base, then the approach must be flown in raw data. An approach may be built for reference purposes only.

Beware... of the man from the FAA, CAA or any other agency who may be riding the jump seat, and if a non data base approach is created and flown using LNAV and VNAV.

[Pilot Pete]

From the Boeing FCTM;
Use of LNAV
To use LNAV for approaches and missed approaches, a proper series of legs/waypoints that describe the approach route (and missed approach) must appear on the LEGS page. There are two methods of loading these waypoints:
• Database Selection
(text removed)
• Manual Waypoint Entry
Due to potentially inadequate terrain clearance, manual waypoint entry should not be accomplished for RNAV or GPS approaches, nor should this method be used with VNAV after the FAF.
When no procedure is available from the FMC ARRIVALS page, manual entry of a series of waypoints may be accomplished to define the approach routing. The waypoints may be conveniently defined by using names of waypoints or navaids in the database, bearing/distance from such fixes, intersections of radials or latitude/longitude information..................If the approach is not available in the NAV database, select the landing runway from the FMC ARRIVALS page. The runway and associated extended centerline then displays on the map to aid in maintaining position awareness. Pilots should not become involved in excessive “heads down” FMC manipulation to build map displays while at low altitude. Raw data VOR, ILS, and ADF displays should be used to avoid distractions during higher workload phases of flight. Map building should be avoided below 10,000 feet AGL.


So it comes down to state/ company rules as you can use LNAV (and VNAV with limitations) according to Boeing. We can't do VNAV approaches (company rule), but I built an LNAV track the other day for a non-fmc database approach, using raw data as my primary means of navigation, but tracking very nicely in LNAV. Worked a treat.