Non precision MDA/DA

[Chally604]

Hello Forum,

sorry, but did I miss something the last few month?
I was always the opinion that Non Prec. Apps (talking of NDB now) are MDA based.

Means that I have an altitude which I will not bust.
Bombardier tells you to add 50 to the MDA and call it a DA and perform a GA if you haven't seen the light until then.

But no matter what the Bomabrider procedure is,... have a look to LOWL or LOWS. Check the NDB APPs.

They post a DA there.
Why? What would you do? To be on the save side, as long as I do not know why there is no MDA, I will still add 50 ft and perform GA there. But seems strange for me. If you read strictly the paper you can bust the DAs on those Non Prec. Apps. :confused:

What's you opinion?

Thanks for you help.

[OPEN DES]

Check the side of the plate. It probably says PANS-OPS 5.
PANS-OPS 5 now caters for constant angle non precision approaches.
If it says DA on the chart, use it as an DA. The loss of xx ft after initiation of the G/A has now been taken into account. There are not many procedures which are PANS-OPS 5 now (Europe) so the MDA+50ft is not completely a thing of the past.

Regards

[BarbiesBoyfriend]

Its 30' where I work.

The idea is that, lets say MDA is 400', you add your 50' so that gives you 450'.

You do the approach and at 450' you see nothing.

You start to go around but the a/c is still descending.

As you started the GA 50' above MDA, even though it takes a moment or two to arrest your descent, and you lose a bit of height as you do so, you don't go below MDA.

Whereas if you started the GA at MDA, you surely would.

Now, back in the day, you'd level at MDA and then clatter on until you reached the MAP or saw the runway. The so called 'Dive and Drive', so no need for extra height.

Perfectly good, IMHO, but far far too dangerous.:hmm:

[BOAC]

Challey - some good stuff here http://www.pprune.org/tech-log/401043-mda-constant-descent-npa.html. (http://www.pprune.org/tech-log/401043-mda-constant-descent-npa.html)

BBF - try not to tread on any squeaky floorboards outside the bedroom or we will have to hear again how great the ?Fokker Tri-motor was it? at 'dive and drive'.:)

[fireflybob]

BBF - try not to tread on any squeaky floorboards outside the bedroom or we will have to hear again how great the ?Fokker Tri-motor was it? at 'dive and drive'.

BOAC, now I wonder who you are referring to?

[Chally604]

@Ken

Thanks, of course that is what the approaches are all about. But check the plates. You will find NDB Apprs with a DA not MDA.

@Open Des
Thanks that was the right answer :ok: found Pan OPS and changed issues on the new plate are minimums an descent angles.

@BOAC
Thanks BOAC thats a good link.

All of you thanks for support.

Cheers

Chally

[BarbiesBoyfriend]

BOAC

Fokker tri-motor????:confused:

Am I getting old?

(it was when I was on the Shed. ;))

Chally 604.

Re minimums. While you and I all do the old stabilised app stuff,CANPA or whatever it's called.

If you were a dive and drive operator you'd want the 'proper' MDA would you not?

Not everyone has bought the CANPA stuff and non precision apps are as old as it gets in aviation these days.:)

[OPEN DES]

If you were a dive and drive operator you'd want the 'proper' MDA would you not?

Normally on these PANS-OPS5 approaches you cannot 'dive and drive' as terrain separation is based on the published descent angle.
CANPA is not much harder on a old-fashioned aircraft. ALT vs. DME using V/S will do the trick just fine.

Regards

[Chally604]

Yeah sure. I like it. If you want it basic, HDG + V/S is perfect and works always fine. Adjust your V/S by the altitude deviation at a certain mileage times two and you fly this thing like an ILS. :ok:

Take care

Chally

[Denti]

Flying it like an ILS is done by simply pressing the approach button, even the usual presentation to the pilots nowadays is exactly like an ILS :)

But yup, it is sometimes good training doing it the old fashioned way with HDG and V/S using the altitude/dme table on the approach chart.

[john_tullamarine]

BOAC, now I wonder who you are referring to?

C'mon, now, chaps, let's be nice ...

[Pontius's Copilot]

Chally

If you are working for a European operator, then EU-OPS 1.430(d)2 says ...

(d)2. All non-precision approaches shall be flown using the continuous descent final approaches (CDFA) technique unless otherwise approved by the Authority for a particular approach to a particular runway. When calculating the minima in accordance with Appendix 1 (New), the operator shall ensure that the applicable minimum RVR is increased by 200 metres (m) for Cat A/B aeroplanes and by 400 m for Cat C/D aeroplanes for approaches not flown using the CDFA technique, providing that the resulting RVR/CMV value does not exceed 5 000 m.


So an NPA flown under these rules is effectively an approach to a DA.
Perhaps some states/airports publish minima including the increment for GA transition, perhaps your Bombardier reference has adopted the terminology; but your company should specify whether to add (50ft) to any NPA minima or not.

[411A]

BBF - try not to tread on any squeaky floorboards outside the bedroom or we will have to hear again how great the ?Fokker Tri-motor was it? at 'dive and drive'.

Not Fokker, Lockheed.
Nevertheless, we still do a variation of dive and drive...and it seems to work quite nicely...for us, anyway.
I would suggest that dive and drive is not for everyone...only for those that do so regularly...and quite safely, thank you.:)

[Hahn]

Correct, as long as you drive a C 411....

[TyroPicard]

BOAC
Took three days - need stronger bait...

[411A]

Took three days - need stronger bait...

Much stronger.:}

[john_tullamarine]

411A, for those of us who have been around longer than a week or two, has shown that he is made of much stronger stuff than would see a man tremble in the face of a bit of incoming ...

[B-HKD]

Fact is, most of the 'pilots' around here seem to know little about flying! Scares the hell out me! I sure hope I won't be learning from some of you guys one day :eek:

Luckily there is always 411A to save the day and remind you of how to fly the thing :cool:

411A is the man! :D

[Capn Bloggs]

Flying 100-200ft below the exact 3° profile on an NPA makes a lot of sense (provided the limiting steps allow). You can actually get to the MDA, level off (drive, shock horror), get visual and land, as opposed descending nicely down the precise 3° slope, to getting to the MDA during the level-out but not being able to land because you're now above the PAPI. It's called wriggle room. :ok:

[BleedingOn]

Bloggs,

The idea is that you DON'T level off! You continue your stabilised approach if you have the required visual references at MDA/DA or you initiate a go-around. There's no mucking around below the profile: you wouldn't do it on a precision approach so why do it on a NPA?

[Capn Bloggs]

Chill out Bleed. We were doing this 20 years ago in jets and it works a treat. If you do get Visual, you fly the aircraft into the VASI and continue on to land. If you don't get Visual, you level off at the MDA then execute the MA at the MAP point. It really is not a big issue. Try a non-database approach without a DME - that's exactly what you would do.

We don't fly 200ft low on a precision approach because a precision approach has a DA. When and if our NPAs have a "DA" as low as the current MDAs, then we will fly down the 3° slope.

[Denti]

The level off thing, or dive and drive, however you wanna call it, is not allowed anymore for AOC-holders under JAR-rules. You have to fly a continues descent final approach to MDA or nowadays DA and execute a go-around if not visual by then.

By the way, Boeings 737 FMC-update 10.8 actually tried that, it flew 200ft low under certain circumstances on NPAs and they had to re-call that update ASAP as that behaviour (and some other snags) were deemed dangerously unsafe.

[Mike_E]

DA is the product of GPS. In the old days, we had MDA - tho shall not descend below which was for nonprecision approaches and we had DH which was for precision/ILS approaches which meant we made a decision at that altitude and started the transition to missed approach or continue to a landing. It was understood that some additonal altitude would be lost in the transition to a climb. Approaches were built with this in mind.

Now move to the 90s and later. The upstart GPS approaches muddle things a bit. GPS is considered a nonprecision approach although a very precise one. For that reason, those approaches that are surveyed and meet certain criteria have a designated "Decision Altitude". This is the GPS/non precision approach stopping point to treat with similar definition as Decision Height. Be careful. Not all GPS approaches have "DA"s some will have "MDA"s. DA minimums are not dive and drive minimums, they are for stabilized VPATH approaches.

Mike

[A37575]

you wouldn't do it on a precision approach

What! Not even a teensy-weensy bit?

[capt. solipsist]

INSTEAD of being "a bit low" on the profile for a CDFA during a NPA with actual limited visibility, it makes better sense to do the opposite -- be "a bit high".

Reason 1: Being so, you're bound to reach your MDA at a closer distance to the runway -- and therefore have a better chance of eyeing the runway --than being exactly on the profile. Sometimes less than a quarter of a mile more is all you need to be visual.

Of course, "a bit high" was in quotation marks to emphasize it being a subjective thing, and that you get above the profile just enough that the required sink rate after becoming visual from your usual 700FPM becomes only around 900FPM.

Reason 2: It plainly gives you a better perspective searching for the runway.

Cheers :ok:

[BOAC]

Being so, you're bound to reach your MDA at a closer distance to the runway - problem with that theory is that for a correctly constructed CD NPA you could then arrive at any given MAP before DA/MDA/DH (/QDR/QTE/TLA....):confused:

Far better to fly the damn thing as planned?

[Capn Bloggs]

INSTEAD of being "a bit low" on the profile for a CDFA during a NPA with actual limited visibility, it makes better sense to do the opposite -- be "a bit high".

Nope. You'd be above slope at the MDA (even though you may well pick up the runway because you are closer) and probably never get stable.

[manuel ortiz]

Denti,

Fully agree with a constant angle descento to a missed.

Could you mention the JAR that forbids a level off to the MAP.

Tks

[FlightDetent]

Could you mention the JAR that forbids a level off to the MAP. That'll be European Council Regulation 859/2008 a.k.a. EU-OPS, OPS 1.430 d(2). All non-precision approaches shall be flown using the continuous descent final approaches (CDFA) technique unless
otherwise approved by the Authority for a particular approach to a particular runway.

FD (the un-real)

[Capn Bloggs]

Can't see any level-off rules/prohibition there...:confused:

You do your CDA, then level at the MDA IAW the procedure, then at the MAP you do your MA. What's the big deal? You (or your company) may choose (require) to do an immediate MA when approaching the MDA if not Visual but is it a requirement?

[FlightDetent]

OPS 1.450 Terminology“Continuous descent final approach (CDFA)”. A specific technique for flying the final-approach segment of a nonprecision 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 15 m (50 feet) above the landing runway threshold or the point where the flare manoeuvre should begin for the type of aeroplane flown.C.B./manuel this of course does not disapprove your point. I'll attempt to dig more later.

[Capn Bloggs]

IMO "without level off" refers to diving and driving down the approach, not the final level-off when at the MDA if not Visual.

[9.G]

Capn Bloggs, there's 2 different approaches using CFDA technique as well:
Approach with a designated vertical profile using the CDFA technique:
a. The optimum angle for the approach slope is 3 degrees, and the gradient should preferably not exceed 6.5 percent which equates to a slope of 3.77 degrees, (400 ft/NM) for procedures intended for conventional aeroplane types/classes and/or operations. In any case, conventional approach slopes should be limited to 4.5 degrees for Category A and B aeroplanes and 3.77 degrees for Category C and D aeroplanes, which are the upper limits for applying the CDFA technique. A 4.5 degree approach slope is the upper limit for certification of conventional aeroplanes.
b. The approach is to be flown utilising operational flight techniques and onboard navigation system(s) and navigation aids to ensure it can be flown on the desired vertical path and track in a stabilised manner, without significant vertical path changes during the final-segment descent to the runway. APV is included.
c. The approach is flown to a DA(H). d. No MAPt is published for these procedures.


Approach with a nominal vertical profile using the CDFA technique:
The optimum angle for the approach slope is 3 degrees, and the gradient should preferably not exceed 6.5 percent which equates to a slope of 3.77 degrees, (400 ft/NM) for procedures intended for conventional aeroplane types / class and / or operations. In any case, conventional approaches should be limited to 4.5 degrees for Category A and B aeroplanes and 3.77 degrees for Category C and D aeroplanes, which are the upper limits for applying CDFA technique. A 4.5 degree approach slope is the upper limit for certification of conventional aeroplanes.
The approach should meet at least the following facility requirements and associated conditions. NDB, NDB/DME, VOR, VOR/DME, LLZ, LLZ/DME, VDF, SRA, RNAV(LNAV) with a procedure which fulfils the following criteria:
i. The final approach track off-set ≤ 5degrees except for Category A and B aeroplanes, where the approach-track off-set is ≤ 15 degrees; and
ii. A FAF, or another appropriate fix where descent is initiated is available; and
iii. The distance from the FAF to the THR is less than or equal to 8 NM in the case of timing; or
iv. The distance to the threshold (THR) is available by FMS/RNAV or DME; or
v. The minimum final-segment of the designated constant angle approach path should not be less than 3 NM from the THR unless approved by the Authority.
CDFA may also be applied utilising the following:
i. ii.
RNAV/LNAV with altitude/height cross checks against positions or distances from the THR; or Height crosscheck compared with DME distance values. The approach is flown to a DA(H). The approach is flown as an SAp.
Note: Generally, a MAPt is published for these procedures. :ok:

So-called dive and drive is still there and can be used it requires the minimum to be increased accordantly. :ok:

[Capn Bloggs]

Thanks 9g.

[FlightDetent]

9g Both your designated and nominal approaches are flown to DA. The next paragraph after your qoute reads (my bolding): The missed approach, after an approach has been flown using the CDFA technique, shall be executed when reaching the decision altitude (height) or the MAPt, whichever occurs first. The lateral part of the missed approach procedure must be flown via the MAPt unless otherwise stated on the approach chart.The way I read it:
- CDFA is constant profile do 50 ft over threshold;
- all NPAs shall be flown as CDFA [EU law since 2008];
- even nominal approaches (no vertical guidance) shall be flown to DA with Miss Approach procedure initiated upon reaching with no allowed level flight towards MAPt [EU law once your operator applies for Appendix (New) to OPS 1.430; every operator must adhere to Appendix (New) by September 2011 the latest]

Sincerely,
FD (the un-real)

[9.G]

The flight techniques and operational procedures prescribed above should always be applied; in particular with regard to control of the descent path and the stability of the aeroplane on the approach prior to reaching MDA(H). Level flight at MDA(H) should be avoided as far as practicable. In addition appropriate procedures and training should be established and implemented to facilitate the applicable elements of paragraphs 4, 5 and 8. Particular emphasis should be placed on subparagraphs 4.8, 5.1 to 5.7 and 8.4.

In cases where the CDFA technique is not used with high MDA(H), it may be appropriate to make an early descent to MDA(H) with appropriate safeguards to include the above training requirements, as applicable, and the application of a significantly higher RVR/Visibility.

This is from the new appendix 1.430.:ok:

[FlightDetent]

Would you say that the quoted Appendix principles

a) allow you to operate opposite to OPS 1.430 d(2) requirement - the paragraph, not appendixAll non-precision approaches shall be flown using the continuous descent final approaches (CDFA) technique unless otherwise approved by the Authority for a particular approach to a particular runway. or,
b) are provided to assist operators under special circumstances exempt from the general rule All non-precision approaches shall be flown using the continuous descent final approaches (CDFA) technique unless otherwise approved by the Authority for a particular approach to a particular runway.?
Also note the quite significant minima penalty When calculating the minima in accordance with Appendix 1 (New), the operator shall ensure that the applicable minimum RVR is increased by 200 metres (m) for Cat A/B aeroplanes and by 400 m for Cat C/D aeroplanes for approaches not flown using the CDFA technique, providing that the resulting RVR/CMV value does not exceed 5 000 m.

FD (the un-real)