IREX, Bob Tait's book and MDA

[kiiga]

Hi there,

In Bob Tait's IREX book there is a number of practice questions that are based on one same premise - if you were conducting a straight in approach by day and successfully broke out of the clouds at some height that is LOWER than the specified circling height, you can then abort the approach (for whatever reason) and join the circuit BELOW circling height.
The book refers to AIP ENR 1.5 par 1.7.3(e) to prove the point.
(There you will find that it's OK to decent below MDA, by day and within the circuit boundaries, and ... etc.)

Yet, two pages later [ENR 1.5 par 1.10.1(d)] AIR says:
A missed approach must be executed if: ...
d) a landing cannot be effected from a runway approach, unless a
circling approach can be conducted in weather conditionsequal to or better than those specified for circling;


So basically if you are below the clouds and below circling MDA - do missed approach ... I guess. Looks like the book is wrong ...

I sent an email to Bob asking to clarify, but he is probably busy - not responding ...
Can someone please tell me if I am missing something here?

[Ted D Bear]

If it's below circling minima, you can't circle - that's why they're circling minima!

[The Green Goblin]

By day provided you have the required vis and 300 feet obstacle clearance you can circle as required to intercept the runway centreline for a landing. So in this case you would descend to the runway approach minima and circle with the 300 feet obstacle clearance, by night you'd descend to circling minima if you needed the reciprocal runway or take the runway approach and land with a tailwind. Operationally you would have a rough idea of the cloud base and if conducting the approach at night and planned to circle on a runway approach you would descend to the circling minima and if not visual and the downwind was acceptable, continue to the runway approach MDA and land if you are visual.

I don't recommend circling at 300 feet unless you're at an aerodrome you know well or in something very docile! (C172)

[JCJ]

Don't forget that is only for day time that you can descend and make a visual approach before the circling area. Following the published approach you can descent to MDA, so If you break free from cloud ABOVE the MDA you may continue visually.

Joining a "normal" circuit is only done when VMC exists.

During night time, if you are clear of cloud, you must still continue to the circling area above the circling minima.

Hope this helps.

[Wally Mk2]

Some good advice here. Yr Q refers to a 'straight in app' therefore the MDA is likely to be less than the circling one. The MDA you planned to make a decision whether to land or not is ONLY for the straight in app procedure unless it's daylight hrs & as others have said can remain at or above 300 ft clear of cloud etc (Cat B) to circle for another runway.
Yr ref to ENR 1.5 par 1.10.1 etc doesn't actually say circling MDA just circling meaning in the case of day & cat B 300ft & all it's limitations.

I at times am forced to circle at 300ft during the day in VMC after having made an app & it ain't fun!!! The books & the boffins will tell you what you can 'legally' do only YOU know what YOU can do in the real world taking into account the rules & Regs & yr personal assesment of the situation at hand.


Wmk2:)

[training wheels]

So basically if you are below the clouds and below circling MDA - do missed approach ... I guess. Looks like the book is wrong ...

Why do a missed approach if you're already below the clouds and visual? Once you're visual, you may then continue to descend below the MDA, as outlined by ENR 1.5 - 1.7.3 for a circle to land.

Yet, two pages later [ENR 1.5 par 1.10.1(d)] AIR says:
A missed approach must be executed if: ...
d) a landing cannot be effected from a runway approach, unless a
circling approach can be conducted in weather conditionsequal to or better than those specified for circling;

This is in reference to using an aid for a runway approach (eg, an ILS or LLZ), but due to excessive crosswinds, you can not effect a landing on that runway approach. So what you do is descend to the circling minima instead (and not the ILS or LLZ minima) and conduct a circling approach to land on a runway that's more suited to the wind direction.

Those who fly to Essendon would be familiar with this when strong southerlies are blowing whilst conducting an ILS on Runway 26. You conduct the Runway 26 ILS as normal but discontinue the descent at the circling minima and then break right for a circling approach for Runway 17.

[increasedescent]

Correct me if I'm wrong, I am a newbie to the IFR world but his question has interested me.

'training wheels' is he not refering to a situation where the cloud base is above the MDA for a straight in approach, but below the MDA for a circling approach? Thus in your example if you continued down the ILS, or your GP for the LLZ to the circling MDA, you would not be visual therefore unable to circle?

The only way around this I can think of is what the others have suggested - if by day, descent to the straight in approach MDA maintain 300' obstacle clearance.

ID

[kiiga]

Thanks Wally Mk2,

I think this is exactly what I was looking for:

Yr ref to ENR 1.5 par 1.10.1 etc doesn't actually say circling MDA just circling meaning in the case of day & cat B 300ft & all it's limitations.

I just hope that this is exactly what people at CASA think when they write the exam questions. :-)

So ... how often do you get to practice this unfunny thing ? :-)

[training wheels]

'training wheels' is he not refering to a situation where the cloud base is above the MDA for a straight in approach, but below the MDA for a circling approach? Thus in your example if you continued down the ILS, or your GP for the LLZ to the circling MDA, you would not be visual therefore unable to circle?

This is the Essendon 26 ILS (http://www.airservices.gov.au/publications/current/dap/MENII01-119.pdf) approach chart. Circling MDA is 1010 ft. ILS minima is 590 ft. To conduct a circling approach from the ILS, you need to be visual at 1010 ft and then break off the ILS there for a circle to land.

[increasedescent]

This is the Essendon 26 ILS (http://www.airservices.gov.au/publications/current/dap/MENII01-119.pdf) approach chart.I must be tired.

I do understand that, what I was getting at was, for example; if you were doing the 26 LLZ (MDA 770') and you did not break visual until say 900' (110' below circling MDA). For whatever reason, before or after you commenced the approach, decided a circling approach was required to another RW, you can then (by day only) abandon the approach and circle to land below the specified circling MDA, provided you maintain 300' obstacle clearance along the intended flightpath of the aircraft correct?

I have never been in this situation but I doubt you would do it at somewhere like Essendon of all places.

Sorry for the 5 line sentence and all the ','s, its late.

ID

[training wheels]

Sorry for the 5 line sentence and all the ','s, its late.

Yep, it is late ;) .. but from what it sounds like, you're trying to lower the circling MDA by continuing the descent to the LLZ minima? If I was in that situation where I had already gone through the circling minima, and couldn't land on the straight-in runway, I'd conduct a missed approach.

The circling minima is set higher than the LLZ and ILS minima for a good reason. :)

[AussieNick]

put it this way, if you break visual, but you are visual below the circling MDA, you cannot circle. This doesn't preclude you from continuing the runway approach to the MDA/MAPt as this is lower, but if your needing to consider a circling approach (using Training Wheels example) i'd be looking at holding or a diversion.

[increasedescent]

Thanks 'training wheels' that was my interpretation before GG's comment;

So in this case you would descend to the runway approach minima and circle with the 300 feet obstacle clearance

I am still a bit puzzled, but I haven't even experienced any approach down to minima as yet, so I think I will stick with playing by the rules for now :ok:

ID

[Wally Mk2]

"Kiiga" I am pleased that what I was trying to explain got thru, at times it's difficult to explain something that you know in words so that another understands, posts here show this to be the case. As for the CASA exams? Well their exams I have always felt are there to trip you up more than make you learn/understand anything. Their wording has caught many a pilot out along the way with common sense not being even slightly considered by the gooses who dream this stuff up! As you go thru yr IFR training you will learn much, far more than any text book will teach you, the text books are just a guide mostly (remember humans dreamed this at times rubbish up not machines) somewhere for you to start learning. Sure pass the exams (you obviously have to) but once out there in the real soup then you really start learning. Multi crew pilots in the most sophisticated A/C still stuff it up by CFIT for Eg. So don't think just because yr green that you are perhaps not good enough even the best haven't got a clue at times!

Wmk2


p.s...how often to we do we get to practice this 'unfunny' thing? Too often I reckon but it all boils down to a personal decision at the time despite what the rule books say.

[The Green Goblin]

Thanks 'training wheels' that was my interpretation before GG's comment;

Quote:
So in this case you would descend to the runway approach minima and circle with the 300 feet obstacle clearance
I am still a bit puzzled, but I haven't even experienced any approach down to minima as yet, so I think I will stick with playing by the rules for now

The example I offered is for something like a VOR/NDB which typicically get you down to 500 feet AGL on a runway approach where you will be perfectly legal to circle at 300 feet by day. An ILS will get you much lower and as such a circling approach is not an option at the DA. You could perhaps use the LLZ minima if you were assured of your 300 feet obstacle clearance or you could build your own DA into the minima factoring in local terrain. By night you have no option but the circling minima and must remain at this height until you intercept the normal approach path to land.

300 feet is a dangerous place to be in low vis operations. If you develop a high rate of descent with an increasing bank angle (say over 1500 fpm) you will hit the deck in less than 12 seconds. Pretty easy to do in mist and haze with the runway just sighted trying to manouvre visually!

GG

[hogespa28]

Quick easy one while people are answering IREX questions. How does a BCMG effect your buffer periods? I assume it is the same as a FM however my AIP is out of date and has to reference to it and I cant seem to make the online one doesn't like Macs.

Thanks

[maverick22]

hogespa28,

yes the same requirements apply to BCMG as for FM i.e. 30 mins buffer before or after.

Not that it helps but the Jep reference is ATC 3.2.7. Don't use the AIP anymore

[Wally Mk2]

Here's an interesting scenario seeing as we are talking about IFR stuff.
Ponder over this.
You have been cleared at night to make a visual approach into EN rwy 17 from 2000ft coming in from the Nth East (we get this all the time) This is with the requirement to not do so until established within the circling area (say 3nm, forget the 2.66 for Cat B that's rubbish) or on the EN rwy 17 PAPI. okay that's B&W. But seeing as when at or around 2000ft & still outside of the circling area & not vis with EN's rwy 17 PAPI you are actually visual with ML's rwy 27. So would it be fair to say that you could decend blw 2000ft even though outside EN's requirements whilst observing ML's PAPI on rwy 27 until you are within the EN circling area & or are visual with EN's rwy 17 PAPI then change from one to the other & still be within the legal requiremnts? Sounds complex I know but draw it out if need be

Should be interesting to see what other think about the above
And sorry for hijacking the thread a little but it's all part of the same thing & we can all learn:-)

Wmk2

[The Green Goblin]

(say 3nm, forget the 2.66 for Cat B that's rubbish)

If you're such a girl wally you need more than 2.66 in a King Air, use cat C speeds then you have yourself covered in the event of a prang :)

But seeing as when at or around 2000ft & still outside of the circling area & not vis with EN's rwy 17 PAPI you are actually visual with ML's rwy 27. So would it be fair to say that you could decend blw 2000ft even though outside EN's requirements whilst observing ML's PAPI on rwy 27 until you are within the EN circling area & or are visual with EN's rwy 17 PAPI then change from one to the other & still be within the legal requiremnts? Sounds complex I know but draw it out if need be

As far as my understanding the circling area is based upon the tangents from the runway that you are descending to. You cannot leave the 25nm MSA until you are established in the circling area (for a visual approach) determined by the tangents of the threshold of the runway that you are using. You may then descend to circuit height once established in the circling area or continue on a normal 3 degree glide slope from the MSA to intercept the normal final approach course.

Remember at night you fly as if you were in IMC :E