New Jepps plates - a question?

[Geoffersincornwall]

The new Jepps charts now show non-precision approaches with a 'stabilised descent path' that terminates with a DA rather than an MDA. I have searched for some explanatory material on the correct interpretation of the MAP point but in vain.

Can anyone offer an explanation as to when it is correct to continue to maintain the stated minimum height and when it is not. The term DA tends to imply no level flight permitted but the 'old' MAP appears to be marked on the chart.

Thanks.

G. :ok:

[hands_on123]

There's a few weird things going on with the new jepp plates i notice!

[365GUY]

What is shown on the plate is a Continuous Descent Final Approach CDFA

Search for TGL-44 ACJ Ops 1.430, that has all the info

[Geoffersincornwall]

This is the link - many thanks 365

http://www.jaa.nl/publications/a&gm/TGL-44.pdf

G

[Geoffersincornwall]

The text of the JAA leaflet indicates that a go around is mandatory at DA when flying a CDFA correctly but points out that at the published DA and with RVR at the published minima it may not be possible to see the required visual cues to continue visually even if ground contact is achieved.

This translates into a tip for Sim Instructors to up the vis if you want to achieve a successful approach to a landing. I was wondering why my guys couldn't see the approach lights at DA and now I know.

The old style approaches with level flight to MAP may still be available depending on your OM. CPs please note, we need to know what your OM says on that subject so please make sure your lads and lasses are aware if they present for TR or Recurrent Training.

G.

[212man]

I think the point is that although CDFA NPAs are now industry standard - as promoted by the FSF ALAR programme and through JAR OPS NPA 41 (which is now incorporated in EU OPS-1) it requires the individual approval of NPAs by the NAAs to use the MDA as a DA. Generally operators use MDA+50 ft as a company DA to avoid penetrating the MDA. However, some MDAs are being approved as DAs and in this case descent below MDA is allowed. It must be clearly approved though. One thing the new Jep plates show - without any approval implicit - is the CDFA profile encoded into the Nav database, along with the waypoint names. Very useful!

[Outwest]

to use the MDA as a DA.

Just to clarify this 212man, do the plates show both an MDA and a DA? Or do you mean an altitude that was previously shown as an MDA is now shown as a DA?

[WIGYCIWYT]

Since both JAR-OPS 1 and EU-OPS are for fixed wing only, surely CDFA’s do not really apply to rotary wing ops? IIRC they were brought in by industry to get around the difficulty experienced in large fixed wing aircraft of moving from a non-precision approach to a landing, bearing in mind the NPA’s are sometimes offset from the centre line, and a ‘level’ segment didn’t help.

As an Aerad user, is the ‘normal’ JAR-OPS 3 info available on the Jeppesen plates as well?

[Non-PC Plod]

No, and therein lies the problem - When the plate shows only a DA, and not an MDA, do we assume that the DA must be at least the same or higher than the MDA?
It would appear logical that way, if you dont descend below the DA until you are visual, you must be also above the MDA. However, I dont say anything which says in black and white that you can do this.:uhoh:

[JimL]

You might be interested in this Safety Reminder Message from Eurocontrol (dtd. 03/02/2010):

SYNOPSIS

 EUROCONTROL has been advised of concerns about the use of Decision Altitude/Height (DA(H)) instead of Minimum Descent Altitude (MDA(H)) as the aerodrome operating minima (AOM) on some non-precision approach charts produced by Jeppesen for countries applying “EU Ops”. This has become a source of confusion and has implications for aircraft operators.
ANALYSIS

 Commission Regulation EC 859/2008 dated 20 August 2008, EU Ops 1.430(d) 2 (applicable from 16 July 2011) states that “all non-precision approaches shall be flown using the continuous descent final approaches (CDFA) technique”.

 EU Ops, 1.435.9 defines CDFA as, “A specific technique for flying the final-approach segment of a non-precision instrument approach procedure as a continuous descent, without level-off from an altitude/height at or above the Final Approach Fix altitude/height to a point approximately 15m (50ft) above the landing runway threshold or the point where the flare manoeuvre should begin for the type of aircraft shown”. Moreover, Appendix 1 (New) to OPS 1.430, states that, “the missed approach, after an approach has been flown using the CDFA technique, shall be executed when reaching the decision altitude (height…”.

Note: Additional CDFA guidance material is currently under preparation.

 Jeppesen only publish DA(H) on CDFA-based, non-precision approaches where the equivalent national AIP minima is shown as an OCA(H). Where national AIP minima is shown as a MDA(H) or for non-CDFA-based, non-precision approaches, Jeppesen continues to publish MDA(H).

 ICAO PANS OPS definitions:

 Minimum Descent Altitude/Height (MDA(H)): “a specified altitude or height in a non-precision approach or circling approach below which descent must not be made without the required visual reference”.

 Decision Altitude/Height (DA(H)): “a specified altitude/height in a precision approach or approach with vertical guidance at which a missed approach must be initiated if the required visual reference to continue the approach has not been established”.

 Obstacle Clearance Altitude/Height (OCA(H)): “The lowest altitude or the lowest height above the elevation of the relevant runway threshold or the aerodrome elevation as applicable, used in establishing compliance with appropriate obstacle clearance criteria”.

 The DA(H) value shown on the Jeppesen charts is at least equal to the published national AIP OCA(H)) minima for a non-precision approach. Importantly, however, the DA(H) published on the Jeppesen charts does not include any add-on to account for any height loss during the initiation of a missed approach. This is not mentioned directly on the charts, but it is described in the Jeppesen Briefing Bulletin JEP 08-D and in the legend pages to the Jeppesen Airway Manual.

 EU Ops 1.430 (a)1 states that, “an operator shall establish, for each aerodrome planned to be used, aerodrome operating minima…”

YOUR ATTENTION IS REQUIRED

 Aircraft operators are invited to:

 Note the issue above specifically with a review of the need to consider the requirement for an add-on factor to account for height loss at missed approach initiation.

 Share their operational experiences.

 It is critical to flight safety that pilots brief the DA(H) or MDA(H) (as appropriate) so that there is no ambiguity as to what minimums are being used irrespective of the type of approach being flown.

FURTHER READING

 Commission Regulation EC 589/2008 (EU Ops) dated 20 August 2008. SKYbrary - EU-OPS (http://www.skybrary.aero/index.php/EU-OPS)

 ICAO Doc - 8168 PANS OPS

 Jeppesen Airway Manual

 Jeppesen Briefing Bulletin JEP 08-D - 26 Sep 08 at http://www.jeppesen.com/main/corporate/documents/aviation/notices-alerts/hubwatch/BriefingBullentins/abb_jep_08_D.pdf

 Draft Implementing Rule for Air Operations of Community Operators (EASA NPA 2009-02B) (CDFA Guidance pages 155-165). EASA - European Aviation Safety Agency (http://www.easa.europa.eu/ws_prod/r/doc/NPA/NPA%202009-02B.pdf)

For more information contact, EUROCONTROL Safety Alerts Coordinator, Richard Lawrence at: [email protected]

There should be some alleviation from the requirement for CDFA for helicopter operators - this, in recognition that they do not yet have the same sophistication as aeroplanes with FMS/GPS procedures and that the majority of procedures carried out in helicopters are still MDA(H) based (ARA and Pins).

Jim

[Geoffersincornwall]

I teach pilots from all and every corner of the globe and have only Jepps (via JeppView) to use as reference material. The complexities of the situation mitigate against simple solutions but I need a simple solution if I am to succeed with the IFR part of any course.

If, when asked, the student replies that his organisation has no CDFA SOP then I will use the published DA plus 50 feet and fly it in the same way you fly an ILS with the application of GA power at DA+50 unless the required visual reference is available.

The briefing will include a simple explanation that:
a. Where an MDA is shown on the plate for a Non Precision Approach the approach can be flown in the 'old' way with a level off at MDA and a GA to be initiated at the MAP.
b. Where a DA is shown with no explanatory information the DA + 50 will be the rule.
c. Where there is an indication that use of the DA has been approved because the re-evaluation of obstacles in the context of a descent below DA during a GA then the DA may be used without the 50 feet increment.
d. Visibility parameters will need review when setting up the sim weather if a 'break-out is required for a revised DA plus a revised GA point will put the pilot flying in a position where the published vis minima will almost certainly be inadequate.

Would appreciate feedback on this approach to the problem.

G. :ok:

[scotbill]

Considering that the continuous descent approach to MDA was in vogue in airlines like the old British European Airways more than forty years ago it is amazing that a dirty dive and level-off should still even be considered as appropriate for large aeroplanes.
As a wise airman of my acquaintance pointed out: "Once you have levelled off at MDA, you are halfway into a go-around anyway". The practice of attempting to resume the approach from level flight at a few hundred feet above ground has led to numerous accidents all round the globe.
In the simulator have seen many pilots demonstrate that a continuous descent non-precision approach can be flown within instrument rating ILS limits, thereby insuring that the aeroplane is perfectly positioned on the notional glideslope.

[JimL]

Geoff,

The missed approach depends for obstacle clearance on being started from the MAPt; revising the procedure is not a simple matter and it must obey the basic principles of the regulations of the State in which it is being undertaken.

Providing the VNAV that results in the RNP APCH or RNP AR APCH, or the process that results in the non-precision approach overlay should not be undertaken in an ad hoc way but should be part of a SMS approach to provision of CDFA (advice should be sought for the non-cognoscenti).

There is a substantial difference in the provision of the DA(H) or MDA(H) - as examination of ICAO Doc 8168 Figures I-4-1-2 and 3 will illustrate. As you will see from these diagrams (which I have sent to you), the OCA(H) will have height additions which result in the 'lower limit' and 'margin' which are used in the provision of DA(H) or MDA(H). These additions will include both those mandated by the State's regulation and those added by the operator in providing the OM limits.

You might/will find that not all States (EASA, FAA etc) use the same process, it might be difficult therefore to provide a simple set of rules. As a first step you could examine any CDFA profiles that have been provided in your operator's OM - this will give you a good idea of how much progress has so far been achieved towards the provision of CDFA procedures.

Jim

[Geoffersincornwall]

Jim

Number one problem is that CDFA is not well understood by most helicopter pilots and there is a great shortage of written SOPs in many parts of the world. My first task as a sim instructor is to reinforce the SOPs in use by my customer. Where these do not exist - about 75% of the time - I teach and therefore use a generic form of MCC and JAR-based protocols.

When teaching on a TR or Recurrent course I am essentially teaching how to manage the systems that are new to the student or improving his understanding during recurrent courses where IFR features. I need to set targets in the brief and make sense of the chart annotations used, in our case by Jepps. I have solved one mystery and that is to answer the much asked question "why is the Missed Approach Point displayed on a NPA chart featuring a DA?" The answer is that any turn described in the MA Procedure should not be initiated before the indicated MA Point.

My intention is not to deliver a de-facto solution for any NPA but simply provide realistic targets during the brief and be able to answer the 'why' question at a basic level. The material you provided goes a long way to helping with that but obviously I will have to make it clear that NAA guidance and OM instructions will always take precedence.

G.

[Non-PC Plod]

Geoffers,

Sounds like an issue for the training standards department!:E :{

[Geoffersincornwall]

Further discussions with JimL have highlighted some issues that are so dependent on specifics (particular type of approach at a particular airfield) that the wisdom of a general approach must be in question when used as a teaching objective. Instead of my suggested 'published DA +50 ft' during training exercises it may be a wiser choice to use the published DA as is and to include a discussion of the OCL issues in the brief.

The essential as far as I am concerned is that when the helicopter arrives at the DA/MDA we (crew and instructor) all know what to expect and that my explanation to the crew as to why we will fly a CDFA in this way is an intelligent interpretation of the regulatory (and advisory) material available.

I welcome discussion on the subject.

G.

[212man]

Geoff, I'm not sure why you would add 50 ft to a DA? If published as such then treat it as exactly that - a DA. The addition of 50 ft is reserved for the MDA to ensure it is not breached during the missed approach - often called a Company DA. It's not scientific, but widely practiced and empirically, it works!

On the face of it, it seems very simple to use this procedure, but careful briefing and cross checking with the FMS is required. Most FMSs will code the V-Path to cross the threshold at 50 ft (TCH) with an angle between 2.75° and 3.5° depending on the step down fixes - but ideally 3°. What's important is to appreciate the relationship between the MAPt and the MDA crossing point, and the FMS should show you. If the MAPt is some way before the threshold you will probably reach it first and maybe some way above the MDA. On the other hand, if the MAPt is close to, or even beyond, the threshold, the MDA will be reached first.

To those who say that the CDFA technique is not relevant to helicopters, can you answer how exactly you are supposed to carry out the visual segment of the approach if you spot the runway as you cross the threshold, or are halfway down it (mid-field NDB?) at 600 ft? far better to look up at a familiar sight picture and a set of PAPIs in front of you!

The missed approach depends for obstacle clearance on being started from the MAPt; revising the procedure is not a simple matter and it must obey the basic principles of the regulations of the State in which it is being undertaken.

Jim, I assume you are cautioning against starting the MAP after the MAPt? Clearly, commencing the missed approach before it is acceptable and might be a result of many other factors - ATC, equipment failure, unstable (FW) etc

[Geoffersincornwall]

Sorry I misunderstood your earlier suggestion re. +50 feet and was trying to adopt a 'safety-first' approach given that a conventional 'old out, new in' update process necessarily means that we cannot compare old with new - or the MDA as was with the DA as now is.

The absence of explanatory material has not helped.

Out of interest which websites would you (and others are welcome to contribute) recommend as essential reading for (a) professional helicopter pilot, (b) helicopter instructor and (c) sim instructor.

Will be interesting to see what comes out of the woodwork.

G.

[212man]

I'd recommend the Airbus safety library, which has all kinds of useful publications. Many are similar in content to those on the Flight Safety Foundation site, but generally more reader friendly.

This is a guide on flying NPAs as if PAs: http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-GEN-SEQ02.pdf

Here's the library site: Safety Library | Airbus, a leading aircraft manufacturer (http://www.airbus.com/company/aircraft-manufacture/quality-and-safety-first/safety-library/)

Here's the FSF site for approach and landing accident reduction:
ALAR Briefing Notes in English | Flight Safety Foundation (http://flightsafety.org/current-safety-initiatives/approach-and-landing-accident-reduction-alar/alar-briefing-notes-english)

Other good sites where are skybrary.aero and smartcockpit.com

[JimL]

212man,

Caution must be exercised when starting the missed approach before the MAPt - unless it is straight ahead; a MAPt with a turn started too early might put the helicopter into an obstacle area.

For this reason, each procedure must be examined before such choices are made.

You raise an interesting point about the location of the MAPt on the angle between the FAF and the threshhold crossing height. We all make the assumption that an overlay procedure will work without modification but, clearly, the FMS has to be programmed with an algorithm that takes account of that or the procedure has to be hard-wired with a DA at the MAPt.

Are there still procedures out there that have the MAPt after the threshhold?

Jim

[212man]

Jim,
if you commence the MAP before the MAPt then clearly you must continue the azimuth guidance to the MAPt before commencing any turns. This is not news though, and is equally applicable to an ILS with a MAP before DA.

Yes, there are MAPts beyond the threshold - many non-DME approaches will have the MAPt at the navaid - NDB or VOR - which may well be somewhere on the aerodrome.

[FlightPathOBN]

This is from PansOps 8168 Ammend 14...Note the differences in calculating the DA vs MDA from the OCA.

(there are many thread regarding MDA/DA in the tech forum)

http://operationsbasednavigation.com/wordpress/wp-content/uploads/2011/04/NPAPAac.jpg

[WIGYCIWYT]

212 man

Surely there are two distinct points here? The first is whether or not CDFA procedures are “mandated” for helicopters - surely they are not since all of the guidance / regulation appears in FW material (e.g Eu-Ops, from which helicopters are expressly exempted).

The second point is a discussion over whether or not it is a good, better or worse procedure for helicopters. That isn’t a straightforward answer, since it doesn’t aid older helicopters at all, but just adds height to the minima (the CDFA ‘DA’ is always higher than an MDA(H)).

Your point about what to do when the missed approach point is past the threshold is surely moot? This is really just the official point from which to start the Go Around - I certainly wouldn’t expect to try to recover from there BUT I will have probably been flying a level segment at the minima for some time prior to the MAPt so would expect to commence a visual approach from somewhere before the MAPt - possibly from a similar geographic position that the CDFA would have put you at, but from a lower altitude.

I just don’t think we have the same problems as the FW guys with the ‘level ‘ bit of the current procedures, particularly at the sort of airspeeds you can elect to fly the approach if it looks marginal.

We have had no indications at all from the Authority here that we are expected to use CCDFA procedures.

The quickest answer to Geoffers problem is surely to switch to Aerads?!

[FlightPathOBN]

The FAA criteria for Helicopter procedure design is 8260.42B, and uses constant descent angle of 4 degrees as a starting point...

http://operationsbasednavigation.com/wordpress/wp-content/uploads/2010/11/HeloCDA2.jpg


http://operationsbasednavigation.com/wordpress/wp-content/uploads/2010/11/HeloCDA.jpg

[JimL]

There is currently a debate going on about whether to encourage helicopters to use CDFA procedures; as someone has already said, in EU-OPS the penalty for not flying a CDFA approach is an increased RVR (and this can be waived by the Authority). A similar penalty is likely to apply to EASA OPS.

It is not clear (to me at least) where WIGY' has obtained the information that the DA(H) will always be higher than the MDA(H) - certainly the DA(H) calculation in EU-OPS Appendix 1 (New) to OPS 1.430 appears to be the same for a CAT 1 (system minima 200ft) approach and CDFA with the exception of the 'system minima in Table 3' (which ranges from 250ft - for a localiser with or without DME, to 350ft for a vanilla NDB; with an RNAV/LNAV at 300ft).

As the level segment of an MDA(H) approach can be flown in IMC it is likely that the minimum speed will be governed by the Flight Manual (Vmini). Some gains here though as approach speeds are between 70kts and 90kts - lower than for our heavy fixed wing brethren.

There has been representation to EASA not to mandate CDFA (with its addition to RVR) for helicopter and they are unlikely to press the issue. (As was previously stated, this could have had an effect on the ARA (DH below system minima) and complicate Point in Space procedures.)

There is likely to be encouragement from the Authority (EASA) to move to CDFA for airfield procedures as there is no doubt that it does improve safety (as has been seen in the ALARP work).

Moving to AERAD only postpones the inevitable.

Jim

[FlightPathOBN]

Jim,

I would concur with you, with the criteria basically being massage FW procedure. The tables, speeds, and parameters just dont fit..a helo is not the same as a CAT A aircraft, Vmini is a major issue, and a reliance on PinS procedures.

When the .42B criteria came out, I was hoping for industry feedback, it just appears it was largely ignored...

[gribbs]

Just a couple of points:

1. Continuous descent approaches are not yet mandatory for helo ops. There are procedures in Europe, however, where there is no option, in that only a DA is published for the non-precision approaches. Even though they're not mandatory for helos, clearly we may need to fly them and thus need to know how they work.

2. Several states have simply relabelled MDAs as DAs without any thought as to why there's a difference. However, just because there may not be a difference between the new DA and the previous MDA does not mean that there is an error; although the two are calculated differently there's no reason that a DA should necessarily be higher than the MDA it replaces.

3. The MAPt is simply the LATEST point by which you must commence a go-around; you're quite free to go around earlier. In fact, if you follow the letter of the 1173/1174 forms precisely (LST/LPC) they say "NPA down to the MDA" and "go-around on reaching the MDA", thus there is no need for a level segment for licensing purposes and the pilot (unless briefed otherwise) should start the MAP on reaching minima.

4. Unless the plate specifically says that you must continue to the MAPt before commencing the go-around then you can turn as soon as you like since the area in which obstacles are considered includes those as far back as the FAF. I'd not advise this, however.

5. Continuous descent non-precision approaches with a DA are still NON-precision; they don't become precision approaches simply by the change from an MDA to a DA.

6. Some aircraft have a Pressure Error Correction (PEC) which must be added to the minimum altitude for precision approaches since the pitot lags and over-reads in descent. For non-precision approaches this has been allowed to be ignored since there is the level segment during which the baralt will stabilise, but continuous descent profile descents clearly have the aircraft still descending at the DA, so although the law doesn't require it, the sensible pilot will add the PEC to non-precision continuous descent procedure minima.

I don't log on to PPRuNe very often so please direct questions and comments to me at gCAP (gCAP Main Page (http://www.gcap.eu)).