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View Full Version : WHY DIFFERENT MDA FOR CIRCLING APP ON RECIPROCAL R/Ws

stubby1
11th Mar 2011, 03:38
hi

I understand that MDA for circling approach is applicable subsequent to an airfield app aid instrument procedure (non electronic glide path).

Then on breaking off from lets say 09 VOR app I can choose to circle to land on 09 ( if straight in criteria not met) or 27.

How come then on some app plates there are different MDA for circle to land for 09 & 27.

Am I missing something ?:ugh:

Centaurus
11th Mar 2011, 12:19
Depends on the position of the critical obstruction that affects each runway. Quite common to see different circling MDA for each runway.

aterpster
11th Mar 2011, 13:28
stubby1:

I understand that MDA for circling approach is applicable subsequent to an airfield app aid instrument procedure (non electronic glide path).

Do you have a specific example?

aslan1982
11th Mar 2011, 14:13
I think it has to do with flying the missed approach procedure for the the initial Instrument Approach.

For example at Dublin

Flying the VOR approach to 16 for a circle to land at 34

We set the minimas for 16 as this was the approach we flew and it will be the go around procedure we follow at any stage during the procedure.

The go around for 16 is climb on track 155 degrees to Killiney climbing 3000feet

Whereas the go around for 34 is climb straight ahead to 3000 and contact ATC

So even if we are at 300 feet on finals to 34 and ATC say go around we must follow the procedure for RW 16 which is climb turn and track 155 to killiney.

I know at dublin the circle to land MDAs for 16 and 34 are the same but maybe this might help

I hope I understood ur question right.

Capn Bloggs
11th Mar 2011, 14:28
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.

d105
11th Mar 2011, 16:29
At some airports the circling minima's are different because of neighbouring noise sensitive zones.

aterpster
11th Mar 2011, 17:22
d105:

At some airports the circling minima's are different because of neighbouring noise sensitive zones.

That, and more typically, a high obstacle that can be isolated by sectorizing circling minimums, or even prohibiting circling in a particular sector. But, the procedure makes this clear.

sevenstrokeroll
11th Mar 2011, 19:17
and some procedures don't authorize circling to one side, EG: south of runway, why not take a look at dozens of approaches, especially in mountainious areas.

FlightPathOBN
11th Mar 2011, 21:10
Hold patterns can be an art form in procedure design. There are many, many variables.
Sometimes the MDA is set using terrain/obstacles, ATC may set the MDA for conflicts, and other times, it will be set to help facilitate the approach MVA.
There are numerous hold pattern templates (the FAA has 31 hold patterns) to use, driven by aircraft class, altitude, and holding speeds/turn radius/bank angle limitations, therefore the size of the hold pattern may also drive the MDA.
There are also engine out hold patterns...

BOAC
11th Mar 2011, 21:21
We set the minimas for 16 - well, if you did that in the UK you would have your bottom smacked!

So even if we are at 300 feet on finals to 34 and ATC say go around we must follow the procedure for RW 16 which is climb turn and track 155 to killiney. - why not ask to stay in the circuit?

Capn Bloggs
11th Mar 2011, 23:45
Obstacles and Noise areas are only going to force different MDAs if you mandate a particular circuit direction. For example, if there is an obstacle to the east of the runway, then all circling could/would be at the same MDA on the western side, regardless of landing direction.

Pitch Up Authority
12th Mar 2011, 06:20
Although the MDA is based on obstacles within an area defined by tangents connecting circles draw around the runway thresholds, it occurs to me that the obstacle clearance of the let down procedure itself also interferes.

With this in mind you could expect a different circling MDA, limited by a VOR let down Rwy 09 circling 27 then on an ILS let down 27 circling 09.

I am puzzled

stubby1
12th Mar 2011, 07:59
aviators
am still perplexed. Assume a vor proc which breaks off at an angle to r/w.

First is it not true that shooting vor app for r/w 09 , when i break off at MDA I have a choice of circle to land on 09 or 27(where straight in not possible ).

Now the vor char for 09 on which i did the procedure gives me a circle to land min. should i use it to cicle to land on 27 or 09 itself

Added to this is my Q, why then have diff min.:hmm:

aslan1982
12th Mar 2011, 12:53
BOAC

- well, if you did that in the UK you would have your bottom smacked!

So what minimias do you use. In the case of Dublin for example

So even if we are at 300 feet on finals to 34 and ATC say go around we must follow the procedure for RW 16 which is climb turn and track 155 to killiney.

- why not ask to stay in the circuit?

we must follow the procedures in our ops manual. We cant just do half a go around into a visual circuit. Well its not recommended.

In our circling approach for a go around we make a climbing turn in the shortest direction towards the landing runway and execute the missed approach

BOAC
12th Mar 2011, 15:25
So what minimias do you use. - circling minima like most do.

I would suggest that to fly a full IFR g/a from `1 mile visual final WITHOUT asking to stay in the circuit is bordering on madness!

Pitch Up Authority
12th Mar 2011, 20:37
I agree. What I meant is that the MDA of a NP might be higher than the MDA based on the obstacles in the circling area. For example a NP based on a VOR that is not on the field in combination with a low intensity approach light system.

This might explain why the circling via an ILS on 27 might bring you down to an MDA based on obstacles within the circling area while the VOR on 09 is not able to bring you down to the same MDA as the ILS.

I am just trying to figure out where the original question is based on.

BOAC
12th Mar 2011, 21:18
Stubby - you there? Example please!

Tinstaafl
13th Mar 2011, 04:05
I'd say varying circling minima can be due to a number of obstacle and/or navaid constraints. There are limits to the gradients allowed for different sections of the approach so an obstacle from one direction on final could impose a limit that doesn't occur from another direction. MDA has to allow for the missed approach gradient so an obstacle could intrude into one runway's missed approach but not into another's.

Approach type could make a difference too. Different approaches have to consider different tolerances leading to different obstacle considerations.

blackburn
13th Mar 2011, 04:39
As Centaurus stated Depends on the position of the critical obstruction that affects each runway. Quite common to see different circling MDA for each runway
And as Tinstaafl has also stated, an obstacle could intrude into one runway's missed approach but not into another’s

The MDA whether for a circling approach or a straight in approach is firstly dependant on the critical obstacles affecting either the approach or the missed approach gradients. The critical obstacles are often not the obstacles within the circling area for the particular performance category of aircraft. However once visual an aircraft on a circling approach is then subject to the rules applying to vertical obstacle clearance along the flight path and the visibility criteria determined by the procedure designer.

Hope this helps clarify the problem.

Blackburn

stubby1
13th Mar 2011, 09:40
FRIENDS

Pl look up vor for 08 & 26 VOBZ vijaywada. (how do i get the figure on this mail ?!!)

If i were to break off from vor 08, & circle to land 26, which MDA do i use for cirling. I am following the vor 08 chart & it gives me ;x; height for circle to land. but then the vor 26 chart gives me :y: height.

Guys , as the chart for 08 is in front ,i guess i should follow circling ht i see on it...x: ...but aint i doing circling for 26 ?? shud i flip the chart to vor 26 to take the circling ht :y:

AM TRULLY FOXED. WHAT WUD U DO ???:ugh:

BOAC
13th Mar 2011, 10:30
I can only access the AIP charts and they look as if they have been done by a six-year old! The VOR26 is designated 'CAT A/B' but has minima for CAT C. NDB 26 is designated 'CAT A/B/C' but does not show any minima for CAT C (finger trouble?)

It appears that CAT A/B you circle on 08 from the VOR using a DA of 890'.
Cat C/D you cannot operate in at all!?? There do not appear to be any charts.

CAT A/B you circle on 26 from the VOR using a DA of 680' Cat C/D 890'
Using the NDB for some bizarre reason you use a DA of 680' CAT A/B and I would GUESS 840'for CAT C/D (Which I suspect is a chart error!)

Good luck! It would be useful to see what JEPP/AIG make of this.:ugh:

9.G
13th Mar 2011, 11:46
for the RWY 08 circling 26 is only available for cat A & B aircraft that's it. Use the associated minimas. :ok:

aterpster
13th Mar 2011, 15:10
Jepp charts:

http://terps.com/vobz/VOBZ%20Jepps.pdf

BOAC
13th Mar 2011, 15:38
Hmm. Still confusing, but Jepp have done well considering the source material!

I really cannot see why circling differs between runways under PANSOPS. There are no obvious obstacles.

Any idea why Cat C is so restricted?

9.G
13th Mar 2011, 16:51
coz even the straight in approaches are restricted to A&B only. Only NDB RWY 26 is authorized for cat C. I guess it's due to large offset between the RWY and final courses :ok:

BOAC
13th Mar 2011, 17:14
Cannot see the logic. Cat C could easily circle off the 08 VOR.

Aterp - need some assistance here - what is 'FN26' on the NDB proc and the '4.3' and 3 degree slope - are we looking at PRNAV?

aterpster
13th Mar 2011, 17:36
BOAC:

Cannot see the logic. Cat C could easily circle off the 08 VOR.

It wouldn't be the first time PANS-OPS has been tortured by a less than sterling procedures staff.

Aterp - need some assistance here - what is 'FN26' on the NDB proc and the '4.3' and 3 degree slope - are we looking at PRNAV?

That is an On-Airport, No-FAF NDB IAP. Jeppesen has coded a sensor FAF for LNAV (RNAV), thus FN26. They have also coded a 3 degree VNAV path from FN26 to a 50' thresold crossing height. It is 4.3 miles from FN26 to the threshold.

BOAC
13th Mar 2011, 18:22
1) Roger!

2) Is there a reference for the use of 'FN' - I suspect it is a TERPS point rather than a PANSOPS point, and should that chart not be annotated 'RNAV or perhaps 'APV(Baro)' in PANSOPS? I've been all over Jepp (on-line) and have not found anything.

aterpster
13th Mar 2011, 19:05
BOAC:

2) Is there a reference for the use of 'FN' - I suspect it is a TERPS point rather than a PANSOPS point, and should that chart not be annotated 'RNAV or perhaps 'APV(Baro)' in PANSOPS? I've been all over Jepp (on-line) and have not found anything.

Any time a fix is in bracketts [FN26] it is a CNF; computer navigation fix. This is in the domain of RTCA and FMS engineers. It is neither TERPS nor PANS-OPS; rather it is a method of doing an FMS overlay of any ground-based procedure. If the state (India in this case) does not authorize RNAV overlay of the procedure per se, then it goes to the operator's authorization whether or not the underlying nav aid must also be monitored while flying the LNAV (RNAV) overlay.

BOAC
13th Mar 2011, 19:13
Thanks for the clarification - I take it it would 'exist' in the Jepp NAV database then? Is there a Jepp pdf or whatever explaining?

9.G
13th Mar 2011, 19:58
timed approach must be flown conventionally however aided by a FMS way point to commence the descent, quite few of them still out there. We don't have the approaches in the data base only the FN way point for aid the identification of descent point. :ok:

BOAC
13th Mar 2011, 20:19
timed approach must be flown conventionally - only one problem with that!

aterpster
13th Mar 2011, 20:27
BOAC:

Thanks for the clarification - I take it it would 'exist' in the Jepp NAV database then? Is there a Jepp pdf or whatever explaining?

This graphic shows two references I found in the Jepp legend. The bottom graphic is the procedure loaded into the Garmin G-1000 trainer, which uses the same nav data as the actual hardware:

http://i201.photobucket.com/albums/aa214/aterpster/CNF.jpg

BOAC
13th Mar 2011, 21:19
Again thanks - I am familiar with 'ff05' but not 'FN' - I assume there is no significance to a pilot in the different lettering - 'ff' / 'fn'? I see also it does refer to a 'Jepp NavData waypoint'.

Incidentally, I reckon that Garmin database is incorrect - it shows 4.3 to the 'map' which is actually the BZ? How can the MAP be the BZ anyway with only a 2 degree track change from THLD? In fact, where IS the MAP on an RNAV approach like that? Surely if the idea is to fly a CDA at 3 deg the MAP must be on the approach track at 680/890 (not 490!)? It looks like someone in Jepp is as confused as I am:). I do hope that is not the actual database for NDB26 at VOBZ which uses the same nav data as the actual hardware: or there may be tears!

Is 'RW26' actually south of the threshold in the database?

aterpster
13th Mar 2011, 22:54
BOAC:

Incidentally, I reckon that Garmin database is incorrect - it shows 4.3 to the 'map' which is actually the BZ?

Highly unlikely that Garmin's database is any different from any other FMS that uses Jeppesen data.

The legal MAP is the NDB, which is 1.1 miles beyond the threshold. Why they coded a different MAP is beyond me. There are many of these remaining in the U.S., (VOR or NDB overlays) but when there were Jepp didn't move the MAP.

reynoldsno1
13th Mar 2011, 23:12
The reason is that circling minima can never be less than the straight-in minima. Consequently, differing minima for the runway approaches may result in the circling minima being raised for one runway only.

Circling minima are calculated independently of the navigation aid used, and have different obstacle clearance requirements and a fixed visibiity requirement.

Straight-in minima are determined dependent on the navigation aid used, and visibility requirements may vary dependent on visual aids available and the MDH. If these are greater than the equivalent circling minima, the circling values must be raised.

BOAC
13th Mar 2011, 23:55
Aterp - if that is a genuine Jepp product you have screenshot then there is a serious error which needs addressing with great urgency. The MDA is dangerously wrong!

Still no logical explanation from anyone for two different circlings at VOBZ. Is it just a co-incidence that the CAT C circling alt for 26 is the same as the VOR minima CAT A/B for 08? Bizarre!

Capn Bloggs
14th Mar 2011, 00:13
I am familiar with 'ff05' but not 'FN' - I assume there is no significance to a pilot in the different lettering - 'ff' / 'fn'? I see also it does refer to a 'Jepp NavData waypoint'.

We have FDs here as well.

The legal MAP is the NDB, which is 1.1 miles beyond the threshold. Why they coded a different MAP is beyond me. There are many of these remaining in the U.S., (VOR or NDB overlays) but when there were Jepp didn't move the MAP.
We have numerous examples of this here in Oz. I believe Jepp codes it that way because they assume, as it is a runway approach, you will not be circling after passing the threshold and not Visual. Therefore the runway threshold (RW26) is coded as the "end" of the approach although our coding also has the navaid after RW waypoint, then the MA climb.

Of note is that the database track from the "FAF" waypoint eg from FN26 to RW26 will not be the charted track if the navaid is offset. Because of an ARINC rule ("if FF, RWY and MAPt all lie within 0.14nm of the same track"), Jepp are able, and do, code direct to the RW26 waypoint from FN26. Obviously, if the navaid is offset, the flown track will diverge from the charted track, with the aircraft tracking "straight" at the threshold whilst being offset (requiring a double-turn when Visual), instead of crossing the centreline at around the MDA on the charted track, requiring only one turn onto final. Practically, this can be a real problem as the crew is presented with a significant double-turn to get lined up on final after becoming Visual.

aterpster
14th Mar 2011, 00:38
BOAC:

Aterp - if that is a genuine Jepp product you have screenshot then there is a serious error which needs addressing with great urgency. The MDA is dangerously wrong!

The two VOR IAPs don't have an altitude coded at that point. Why the 490 on the NDB is beyond me. It does seem to be a coding error. Nonetheless, a properly trained crew is to predicate MDA on the chart, not anything in the database.

Still no logical explanation from anyone for two different circlings at VOBZ. Is it just a co-incidence that the CAT C circling alt for 26 is the same as the VOR minima CAT A/B for 08? Bizarre!

That is a question only the Indian procedures design staff could answer.

BOAC
14th Mar 2011, 00:49
Capn Bloggs - useful stuff there. I hope, however, in Oz you have the CORRECT DA in your coded approaches:sad:

Sure gets complicated when you 'twist' an offset approach into a straight-in for a computer - how do you GET to the MAP if it is the NDB and if it isn't, how is the obstacle splay affected by 'moving' the MAP to either the threshold or abeam the NDB?

Presumably if you went round off Aterp's VOBZ NDB26 you would need to go left to pick up the NDB 250 track - or would you just fly the 'RNAV' track to the north of the correct track? My head hurts.

Capn Bloggs
14th Mar 2011, 01:18
Presumably if you went round off Aterp's VOBZ NDB26 you would need to go left to pick up the NDB 250 track - or would you just fly the 'RNAV' track to the north of the correct track? My head hurts.
Disregarding the track dislocation :eek: at FN08, for a bit of head-spinning, take a close look at at where the magenta line goes in the region of the threshold. The NDB is just north of the opposite threshold (26).

http://i521.photobucket.com/albums/w334/capnbloggs/YPKANDB08ApproachND.jpg

9.G
14th Mar 2011, 08:16
BOAC, this is NOT a RNAV approach. It's a NDB approach constructed in accordance with PANS OPS 4 as shown in the left bottom corner. If it was overlay the title would be GPS or NDB approach. Once you've realized that, and rightfully pointed out deficiencies, you simply fly it raw data and use the FN point to commence your 3 degree descent towards the minimum instead of dive and drive. The title of the procedure states clearly what it is and how it must be flown. :ok:

Capn Bloggs
14th Mar 2011, 08:32
this is NOT a RNAV approach. It's a NDB approach constructed in accordance with PANS OPS 4 as shown in the left bottom corner. If it was overlay the title would be GPS or NDB approach. Once you've realized that, and rightfully pointed out deficiencies, you simply fly it raw data and use the FN point to commence your 3 degree descent towards the minimum instead of dive and drive. The title of the procedure states clearly what it is and how it must be flown.
That's not the way thousands of these approaches are flown. The FMS is used to fly the NDB approach; no "overlay" or "title" necessary. The primary purpose of FN26 and RW26 is to facilitate the FMS flying the approach. The final descent path is coded at 3° from FN26 to RW26. You are welcome to fly 3° raw data from FN26, but you may may well pop out above the PAPI at the MDA. If I didn't have a DME or FMS VNAV profile to follow, I'd be going down a bit/earlier than FN26 just to make sure I got to the MDA before it intercepted the GS ie Dive and Drive.

aterpster
14th Mar 2011, 09:03
Capn Bloggs:

That's not the way thousands of these approaches are flown. The FMS is used to fly the NDB approach; no "overlay" or "title" necessary. The primary purpose of FN26 and RW26 is to facilitate the FMS flying the approach. The final descent path is coded at 3° from FN26 to RW26. You are welcome to fly 3° raw data from FN26, but you may may well pop out above the PAPI at the MDA. If I didn't have a DME or FMS VNAV profile to follow, I'd be going down a bit/earlier than FN26 just to make sure I got to the MDA before it intercepted the GS ie Dive and Drive.

You are correct for those who have the necessary AFM and other authorizations. Lacking that an IAP like this one requires monitoring of raw data; i.e., the NDB.

BOAC
14th Mar 2011, 09:10
Given what I see here there is indeed no other way to fly this particular plate. If all this 'Garmin'/GPS NAV stuff (as presented) is progress I want none of it. The whole thing appears to be a waste of effort and certainly possibly dangerous and needs to be put back in the 'interesting' box until everyone catches up.

GPS in itself offers enormous benefit in both situation awareness and ultimately in the flying of an approach, but we do not appear to be 'there' at VOBZ (nor YPKA!) as far as I can see. Capn B - I think if I was presented with that picture I would turn down the screen lighting. Take away the 'magenta line' and we have a useful SA tool. Leave it there.....................?

Regarding VOBZ, since the NDB26 is the ONLY IFR approach for CAT C, I am amazed the the procedure is not annotated NDB/DME!

Lacking that an IAP like this one requires monitoring of raw data; i.e., the NDB. - I cannot follow your logic there ie "requires monitoring of raw data;" - it seems to me that one needs to discard the fancy gizmos and USE raw data? Right now - March 2011, the only advantage I can see for the 'overlay' is for Flight Simmers. Are you saying this sort of flying is actually 'approved'?

I really would appreciate someone who 'knows' explaining why the two circlings are different at VOBZ.

9.G
14th Mar 2011, 09:36
C.B. primary and only approved navigational source is approach plate NOT the BOX. FMS is just advisory and in case of discrepancy Jeppesen prevails. That's how simple it is. You may elect to use it at your own peril and fly it out of the box. :ok:

If the title was, NDB or GPS approach then I wouldn't need to monitor the raw data but simply fly it of the box. Since it says NDB that's the primary navigational source. In case I lost both FMS I still can fly it following the needle unlike GPS. :ok:

Capn Bloggs
14th Mar 2011, 10:06
You may elect to use it at your own peril and fly it out of the box.
Absolutely legal here if it is in the FMS database, as per my pic above. The PM monitors the approach in Rose/Appr display with the NDB needle. FMS Profile monitoring is not relevant as there is none.

In fact, the ADF display in my machine is so bad that the "only" way to do an NDB approach is with the box.

BOAC
14th Mar 2011, 10:38
the "only" way to do an NDB approach is with the box - I shudder to think how you do that based on the image you posted:suspect:

Capn Bloggs
14th Mar 2011, 11:38
Yes, well, that's not an example of a well-programmed database approach! :{

Most are a bit better than that and do make life very easy/safe. :ok:

9.G
14th Mar 2011, 13:46
C.B. one must pay very close attention to the details on the charts namely on your example GPA is shown in brakets (most probably ending at 50 ft over the THR.) thus it's the data based and the NDB approach RWY 08 can be flown out of the box with vertical guidance yet must be monitored by raw data. VOBZ, on the other hand doesn't have GPA in brakets, meaning it's a geometrical projection from the THR 3 degrees upwards. Now you tell me, will you fly this approach in LNAV/VNAV mode? Most probably you'll end up flying it in LNAV monitoring the needle and going V/S or FPA on the vertical mode. Not really overlay if you ask me. :ok:

aterpster
14th Mar 2011, 15:07
Some of this has to be laid at the door of the Indian aviation authority. Not only is there the imponderable about CTL minimums, both VOR IAPs should be VOR/DME because (forgeting LNAV for a moment) both require a DME fix for the FAF.

In my current Garmin database at least, both of these IAPs are called VOR/DME. Jeppesen apparently has that latitude with their database unlike the actual chart. Well, I guess the VOR 26 can be flown without DME as shown by the broken line in the profile. But, there is no such option on the VOR 08.

Maybe the guy who designed these IAPs also issues ATPs to Indian pilots.

As to wheter these three IAPs can be flown by an LNAV aircraft without use of raw data that is true for some operators, not true for others.

As to containment areas, they are very wide compared to the accuracy of LNAV. With U.S. TERPs the primary would be 1.25 miles each side of centerline at the NDB and 1.0 miles for the VOR. I believe the PANS-OPS values are a bit wider than that.

9.G
14th Mar 2011, 16:05
As I said there are quite few of them out there, ZMUB NDB 14 being one of'em. Have a look at that animal and tell me it's an overlay too? :ok:

aterpster
14th Mar 2011, 16:57
9.G:

As I said there are quite few of them out there, ZMUB NDB 14 being one of'em. Have a look at that animal and tell me it's an overlay too?

Indeed it is. It's in the database for monitoring for non-approved operators and for overlay for approved operators. Note the CNF [FN14].

http://i201.photobucket.com/albums/aa214/aterpster/ZMUBNDB14.jpg

9.G
14th Mar 2011, 18:20
Well, flying a scheduled service to ZMUB the only thing I can say it's not in the data base. What is the data base is the way point FN14 where the descent will be commenced. It's a substitute of FAF in absence of such. Overlay to me is when I can just press the approach button and the a/c flies both LNAV/VNAV following the published NPA profile, NOT the case here. The approach is flown using raw data aided by the FN14 to identify the descent point. :ok:

aterpster
14th Mar 2011, 21:12
9.G

Well, flying a scheduled service to ZMUB the only thing I can say it's not in the data base. What is the data base is the way point FN14 where the descent will be commenced. It's a substitute of FAF in absence of such. Overlay to me is when I can just press the approach button and the a/c flies both LNAV/VNAV following the published NPA profile, NOT the case here. The approach is flown using raw data aided by the FN14 to identify the descent point.

All that says is the equipment you fly into ZMUB doesn't have the procedure in its database. The coding on the chart shows both FN14 and the final segment VNAV path angle. It's up to the airframe vendor and/or the airline what Jeppesen-provided data is included in a particular aircraft or aircraft fleet's nav database.

The database I am looking at has the complete procedure with base legs for A/B and C/D, and a VA leg to 7,600 for the missed approach, followed by a turn back to the NDB.

Anyone who would descend below MDA and past the early MAP is asking for trouble unless good VFR is assured. But, you know that since you fly there.

9.G
14th Mar 2011, 22:03
aterpster, I dunno your data base and I don't exclude discrepancies. One thing though I read on Jeppesen approach chart is the description of approved data based DPA. It states that data based DPA is depicted in brakets unlike this one. I believe, that's the reason why we don't have it in the data base. :ok:

FlightPathOBN
14th Mar 2011, 22:41
I certainly hope that it wasnt manually added....

even CNF's have 5 place settings....

aterpster
15th Mar 2011, 01:11
FlightPathOBN:

I certainly hope that it wasnt manually added....

even CNF's have 5 place settings....

More specifically, it is a sensor fix. They are four letters.

Capn Bloggs
15th Mar 2011, 04:58
C.B. one must pay very close attention to the details on the charts namely on your example GPA is shown in brakets (most probably ending at 50 ft over the THR.) thus it's the data based and the NDB approach RWY 08 can be flown out of the box with vertical guidance yet must be monitored by raw data. VOBZ, on the other hand doesn't have GPA in brakets, meaning it's a geometrical projection from the THR 3 degrees upwards. Now you tell me, will you fly this approach in LNAV/VNAV mode? Most probably you'll end up flying it in LNAV monitoring the needle and going V/S or FPA on the vertical mode. Not really overlay if you ask me.
No GPA in brackets for my NDB at YPKA, approach flown the whole way in LNAV and VNAV. In the database and approved for use. Raw data monitored. We've never had overlay approaches. We went straight to dedicated GPS NPAs (now called RNAV/GNSS) when no suitable navaid approaches exist.

even CNF's have 5 place settings....
Yes, some of our new charts indeed now have 5-letter waypoints eg FS26Y on the YPKA VOR-Y Rwy 26.

9.G
15th Mar 2011, 09:19
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:
The GPS Approach Overlay Program is an authorization for pilots to use GPS
avionics under IFR for flying designated nonprecision instrument approach procedures, except LOC, LDA, and simplified directional facility (SDF) procedures. These procedures are now identified by the name of the procedure and “or GPS” (e.g., VOR/DME or GPS RWY 15). Other previous types of overlays have either been converted to this format or replaced with
stand-alone procedures. Only approaches contained in the current onboard navigation database are authorized. The navigation database may contain information about nonoverlay approach procedures that is intended to be used to enhance position orientation, generally by providing a map, while flying these approaches using conventional NAVAIDs. This approach information should not be confused with a GPS overlay approach (see the receiver operating manual, AFM, or AFM Supplement for details on how to identify these approaches in the navigation database).
NOTE: Overlay approaches are predicated upon the design criteria of the ground-based NAVAID used as the basis of the approach. As such, they do not adhere to the design criteria described in paragraph 5-4-5k, Area Navigation (RNAV) Instrument Approach Charts, for stand-alone GPS approaches. :ok:

Capn Bloggs
15th Mar 2011, 12:18
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
15th Mar 2011, 14:58
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:

http://i201.photobucket.com/albums/aa214/aterpster/YPKA16-1.jpg

9.G
15th Mar 2011, 15:50
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) 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. :ok:

hot_buoy
29th Jun 2011, 03:25
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 http://www.airservicesaustralia.com/publications/current/dap/BCSNB02-124.pdf.

Capn Bloggs
29th Jun 2011, 05:30
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
:confused: The circling MDA is the same for both runways, so why is this example an exception?

stubby1
29th Jun 2011, 07:16
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:8 the verdict?

Capn Bloggs
29th Jun 2011, 07:34
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.