Setting MAA on a VNAV app VS / NPA (v/s, NDB VOR etc)

[skelsey 765]

 

 

So the charts are basically referring to DA then/

 

Only if it says DA on the chart.

 

If it says MDA you need to add 50ft.

[Driver170 42]

 

 

geometric path is not necessarily an idle path.
 
Geometric (adj):
1. Relating to geometry, or according to its methods
2. Characterised by or decorated with regular lines and shapes
 
A geometric path means that the FMC draws a straight line from one altitude constraint to the next and follows it. This may or may not involve idle thrust, but it will certainly involve variable rates of descent as your groundspeed changes and as the gradient between constraints changes.

 

So it calculates the paths to the next altitude restraint, and then navigates them with thrust as required.

It doesn't state on the charts if its DA or MDA 

[JoeDiamond 67]

Only if it says DA on the chart.

 

If it says MDA you need to add 50ft.

 

This will vary with different operators.  We are allowed to use the MDA as a DA without adding 50 feet under any of the following situations:

 

- if the runway has a PAPI or VASI installed.

- If the runway has a published ILS approach we can also use the published MDA as a DA when conducting the ILS with the glideslope inop or a localizer approach.

- the approach has a ball note that reads "Only authorized operators may use VNAV DA in lieu of MDA.

 

In all other cases we would add 50 feet to the MDA, this is rarely the case.

 

Edit:  The approach must also have a coded glide path in the FMC database.

[Driver170 42]

We are allowed to use the MDA as a DA without adding 50 feet under any of the following situations:

 

Edit:  The approach must also have a coded glide path in the FMC database.

 

Is this why operators use DA 

 

 

 

AERODROME OPERATING MINIMUMS ACCORDING TO EU-OPS 1

In May 2008 we asked commercial operators about their plans for this EU-OPS implementation. The following items are directly related to the results of that survey:

 

a. All non-precision approaches will be reviewed to show CDFA (Continuous Descent Final Approach) profile and minimums.

 

b. In case of CDFA only, a DA(H) is shown instead of the previously published MDA(H). The missed approach point is still shown according to state source but the missed approach initiation arrow is moved to the point where the DA(H) is reached.

 

c. Jeppesen charted AOM do not include an add-on when current MDA(H) is replaced by DA(H). Pilots are reminded to check their operator’s Flight Operations Manual or similar documents whether they have to apply an add-on or not.

 

d. For CDFA profiles, Jeppesen will show DME vs altitude bands, distance vs altitude bands or timing vs altitude tables. If not provided by the State source those altitudes will be calculated by Jeppesen.

 

e. Non-CDFA profiles and minimums will be shown in exceptional cases only and may be combined with CDFA profiles and minimums.

 

f. For CAT I operations with full approach light system (FALS) Jeppesen will include RVR values below 750m together with the higher values. Pilots are reminded to check their operator’s Flight Operations Manual or similar documents to fulfill the requirements for using the lower RVR values.

 

g. Lower than standard CAT I minimums are charted on request on customer tailored charts.

 

h. Other than standard CAT II minimums will be charted if the procedure is approved for such operations by the state of the airport.

 

i. Circling minimums must not be lower than the minimums of preceding instrument approach procedure. If circling MDA(H) and/or visibility must be raised due to higher straight-in values, only one set of circling minimums is shown which relates to the highest straight-in minimums.

It mentions below  1. Approach methods: 2D: without vertical guidance, flown to an MDA(H) so why does an LNAV NPA only allow you to fly to the MDA(H)

 

 

The new scheme introduces two types of approach methods (2D and 3D), two types of approach minima (Type 1 and Type 2), in addition to redefining three types of approach procedures (NPA, APV, and PA).

 

1. Approach methods: 2D: without vertical guidance, flown to an MDA(H) 3D: with vertical guidance, flown to a DA(H)

 

2. Approach minima: Type A: minimums 250 ft (75m) or greater Type B: minimums below 250ft (75m), and further divided into CAT I, II and III

 

3. Approach procedures: Non-Precision (NPA): an instrument procedure (IAP) designed for 2D Type A

 

Approach with Vertical Guidance (APV): an IAP designed for  3D Type A

 

Precision Approach (PA): an IAP designed for 3D Type B

[Spin737 102]

 

 

- if the runway has a PAPI or VASI installed.

- If the runway has a published ILS approach we can also use the published MDA as a DA when conducting the ILS with the glideslope inop or a localizer approach.

 

Interesting. How does a PAPI keep you from dipping below MDA? I'd like to know how they sold that to your POI.

[JoeDiamond 67]

Interesting. How does a PAPI keep you from dipping below MDA? I'd like to know how they sold that to your POI.

 

The way it was explained to me was that if the runway has visual or electronic glideslope guidance it complies with the TERPS obstruction clearance plane, or something to that effect.  You can initiate a go-around at MDA and you will still be clear of obstacles.

[Jack C 8]

Seems like there are different ways operators do things that's for sure.