WHY DIFFERENT MDA FOR CIRCLING APP ON RECIPROCAL R/Ws

[Capn Bloggs]

9.G, as I said above, "Overlay Approaches" simply do not exist here, nor do the US rules on flying them. If an NPA is in the DB, we can use LNAV and VNAV to fly it provided we monitor the raw data info.

please have a closer look at Jeppesen plate 16-1 YPKA on lateral & vertical profile VPA is depicted in brakets (3,00) starting from FN08Y till EP08 whereas neither VOBZ bor ZMUB do have it depicted this way.

The NDB 26 at VOBZ does have the top-of-the-drop waypoint; FN26, which is coded 3°, as shown, to the RW 26 waypoint.

Putting it another way, if the approach chart doesn't have the FMS waypoints, it's probably not going to be in the DB (all made by the same company), and guess what: we wouldn't fly it in LNAV/VNAV.

[aterpster]

9.G:

C.B, please have a closer look at Jeppesen plate 16-1 YPKA on lateral & vertical profile VPA is depicted in brakets (3,00) starting from FN08Y till EP08 whereas neither VOBZ bor ZMUB do have it depicted this way. I dunno how to copy paste it here perhaps someone else will be helpful. However here's something to think about:

[9.G]

Thanx aterpster, this is Jepp explanation about VNAV coding and how it's depicted on the charts. It's available on the new briefing strip concept description.

VERTICAL NAVIGATION (VNAV)

Vertical Navigation (VNAV) descent information will appear in the profile view of selected non-precision approaches beginning with charts dated 3 Dec 1999. The VNAV information appearing in the profile illustrates the geometric descent path with a descent angle from the Final Approach Fix (FAF) to the Threshold Crossing Height (TCH) at the approach end of the runway.

The VNAV descent path, depicted with a screened line, is based on the same descent angle coded into the Jeppesen NavData database. Use of this descent angle by certified VNAV-capable avionics equipment will ensure a stable, constant rate of descent that will clear all intervening altitude restrictions. Some approach procedures may require a delay of the start of descent beyond the FAF, until the VNAV descent path is intercepted. The profile view will depict this level segment of flight as required.

The VNAV descent angle appears in brackets along the VNAV descent path and is repeated in the conversion table. Additionally, the conversion table provides a recommended rate of descent relative to the VNAV angle and groundspeed.

The inclusion of the VNAV descent angle does not change or modify existing non-precision approach requirements. Usage of the Minimum Descent Altitude (MDA), as well as the Missed Approach Point (MAP), remains unchanged. In accordance with Federal Aviation Regulations (FARs) and ICAO PANS OPS criteria, do not descend below the MDA until attaining the required visual reference. Additionally, do not initiate the prescribed missed approach procedure prior to reaching the published missed approach point.

NOTE: Operators may obtain permission from their controlling authority to use Decision Altitude (DA) operational techniques when making a VNAV descent. This approval is specific to the operator and to the approach.
VNAV descent is optional. Use of any VNAV approach technique is dependent on operator approval, certified VNAV-capable equipment availability, and crew training.

another question is when will the a/c commence the left turn once the approach has been armed over KA (IAF)? So far I personally haven't seen a coding for timed turn neither in Thales nor Honeywell.

[hot_buoy]

Depends on the position of the critical obstruction that affects each runway. Quite common to see different circling MDA for each runway.

Dunno about that, Centaurus! The PANS-OPS circling area is defined as tangents joining arcs from each threshold. I reckon there can't be an obstacle that is unique to only one runway's circling approach as the circling area as defined applies to all runways.

Sorry to come in so late on this. The only reason that a circling altitude is different on one rwy approach to the reciprocal is that you have made a circling restriction AND that restriction encompasses part of the final or missed approach protection area. In this circumstance, you can not exclude obstacles affecting final or miss as part of the circling evaluation. So an obstacle you can exclude on one approach may not be for the reciprocal direction. Ostensibly, this means every procedure can have a different circling altitude to the same aerodrome. In Oz, the circling altitudes are common across the aerodrome to prevent confusion [as demonstrated above], except where an infrequently used procedure would unnecessarily raise the altitude to an unreasonable value. The Cairns NDB or VOR -B is a good example .

[Capn Bloggs]

Originally Posted by hotbouy

In Oz, the circling altitudes are common across the aerodrome to prevent confusion [as demonstrated above], except where an infrequently used procedure would unnecessarily raise the altitude to an unreasonable value. The Cairns NDB or VOR -B is a good example

The circling MDA is the same for both runways, so why is this example an exception?

[stubby1]

circle to land diff r/w.. what ht to follow?

My doubt remains as follows:-

I am doing a non precision app for r/w 09. I come to MDA .. r/w not sighted .. go till MAP .. sight the r/w but am not placed well for 09 ( laterally or vertically) & decide to do circle to land 27.

Do i refer to circle to land alt for 27. This requires me to flip the new chart, else be prudent enough to have gone through it before.

What is the verdict?

[Capn Bloggs]

If there was a possibility of circling and then landing on 27 after doing the 09 approach, I would have briefed it. If the circling MDA for 27 is higher, and your terrain clearance for your category (cat C: 400ft AGL; assuming day operations) can't be assured for the whole of the circle onto 27 (local knowledge required), to be on the safe side I'd do a missed approach and then do the 27 approach, although this would depend on your configuration and company policy.

It might be acceptable to zip back up to the 27 circling MDA and then circle as desired, particularly if you are still at the circling configuration, not landing config.