2 NDB approach
 

Who knows the max. vertical and lateral deviations on the glide path during 2NDB approach? any formulas?

What glidepath!

NDB approaches are non precision, there may be a list of advisory altitudes (or heights), there may be minimum altitudes (or heights) at certain points and then there will be a Minimum descent altitude below which no part of the aircraft may pass unless the appropriate visual references are in sight.


Max lateral deviation is 5 degrees, though I can't lay my hand on the exact reference for that as I'm in the garden!

How does measure this 5deg.?

You obviously can't go below the MDA (or circling minima, if that is necessary for your approach) or any stop altitudes that are detailed on the plate. If none you are quite allowed to descend to your MDA and maintain that until you reach the MAPt or you become visual with the runway.

In terms of lateral errors permitted you must maintain a QDM/QDR that is +-5 degrees of the designated approach. For example if the inbound QFU is 270 (all magnetic unless stated on plate) your needle on the RMI/RBI cannot deviate more than those 5 degrees either side. So it's your instruments that measure and show you this.

Phil - caution - I don't feel we are talking to a pilot here.

- may be correct in Russia but not under JarOps

If your QDM to the beacon is out by more than 5 deg to the approach path.

It's also easier to look at the plate. I've attached Wonderboom's 2NDB. You will -see that you start at +- 6000' once established. You can descend to 5100' at WB and then continue to the MAPt at WR.

http://www.caa.co.za/resource%20cent..._20NOV2008.pdf

I don't see any wrong with Phil's post. This system is practiced in the NZ & Oz.
You can descent up to your MDA and continue it till the MAPt. or till you become visual.

And as stated by Phil lateral is 5 deg on both sides
And even though vertical is limited to the MDA, I've seen many renowned operators go a bit below, say nothing more than 50-70ft to catch a glimpse of the ground to go for an approach.

Hope this helps.:ok:

KJ

- have another look? It is not 'wrong', just not complete. Do you know if Pensador flies only in 'NZ and OZ'?

BOAC, can you point exact place in JAR-OPS (or EU-OPS for that matter) where it does not allow you to descend to the MDA once all the other altitude constraints on the approach have been met/passed?

If you are talking about CANPA, which is mandatory by many operators, as far as I know it is not mandatory under JAROPS.

SC

ops 1.430

There are of course plenty of exceptions.

No glide path as such Pensador - only the one you construct - as its a Non-precision approach.

I prefer to attain a Constant Path Descent as definately not comfortable with sitting at Minimum Descent Altitude (MDA) early or even going below MDA unless fully visual.

Use check heights or Rate Of Descents indicated on your Jeppie or Aerad plates to monitor the glide/target profile and get your PNF to call out deviations as you go... :cool:

Airbus FPV
 

Quote from Pilot Positive:
Use check heights or Rate Of Descents indicated on your Jeppie or Aerad plates to monitor the glide/target profile and get your PNF to call out deviations as you go...

Yes! And, if you're a lucky Airbus driver, use the "bird": with or without the FD (subject to your SOPs). If using AP, you'll have to anticipate the start of the descent, due to the time/distance taken for the AP to achieve the push-over.

Levelling off at the MDA in a large aeroplane, and - having become visual at, say, 400 ft aal - catching the right moment to start down again, can be a nightmare, particularly at a "black-hole" airfield. :eek:

One thing to bear in mind with the continuous descent is that, if you are not planning to level off at the MDA (and why would you want to in a big jet?), you must go-around from a suitable margin above MDA, to avoid going below it during the G/A.

Chris

If only I were smart and had any idea what an NDB approach is...

er....... not always the case anymore. As you may find that DH is published rather than MDA and in this case it should be treated as a DH and a certain height loss below is accounted for in the procedure.

...would that quote fit on a headstone?

Sorry for question: What do the abbreviations QFU, QDM/QDR mean? For me they are new!

Why worry about NDB approaches. NDB's will all be gone the way of the dinosaurs very soon (at least in the modern world), and good riddance to them.

QDM Magnetic bearing to a station
QDR Magnetic bearing from a station
QFU Magnetic bearing of the runway in use

gusting_45,

I seem to have been hearing that argument since the 'Sixties! Unfortunately, some poor sods still have to do them for real. If you don't:
(a) count yourself spoilt:
(b) don't bother to come on this thread? :rolleyes:

FE Hoppy:

I assume you are right, but the basic principle would still apply; and the DH (or decision altitude?) would have to be type-specific, to cater for different flare performances. If I remember correctly, ILS DHs are normally predicated on the use of a radio altimeter, requiring suitably flat terrain. In the case of non-precision approaches, the latter is often not available, so any decision height/altitude would presumably be associated with a barometric altimeter?

[Some of us are old enough to remember when DHs were first introduced on ILS approaches! Prior to that, in the UK at least, we only had CH (critical height); the ILS equivalent of MDA. We even used to level-off at critical height on an ILS. NOT a good idea, as I'm sure most of our readers are aware, particularly on a jet... :eek: ]

Chris

Because some of the smaller airports cant afford a nice ILS or a even VOR??? :rolleyes:

Somethings are better than nothings ;)