IREX

[Jabberwocky]

I mis-read the daps, the MSA at 12DME is 3500ft. So it's going to be a missed approach, in which case you wouldn't bother descending if you're just going to climb again to 3900ft as per the MA procedures, hence as Kwyjibo has said. But if the MSA is 3500ft, could you not still descend to 3500ft if desired?

I think i need to read over my notes...

[pavlov's dog]

"You are flying from Bathurst to Parkes and conducting a DME arrival in IMC. GPS RAIM is not available. At 12 DME and 3700ft you lose DME reception. Which action would you carry out to continue flight at the lowest permissable level to Parkes?"
Maintain 3700
Continue descent to 3500
Climb to 3800
Climb to 6100
Climb to 3900
I got this one wrong, and I put continue descent to 3500. The reason I put this is that the way I understand missed approaches is that it isn't something you just start doing as soon as something's wrong. You continue to the Mapt and then carry out the procedures. Anyone want to shed some light on this one?

Hi Unobvious,

At 14 DME on the BTH-PKS track you are clear to descend to 3500ft. 25nm MSA is 3900ft, 10nm MSA is 3800ft. A few paragraphs from AIP apply to this problem:

ENR 1.5 para 1.10 (b)

1.10 Missed Approach - Standard Procedures
1.10.1 A missed approach must be executed if:

b. during an instrument approach and below MSA (as specified
on the IAL chart) the performance of the radio aid becomes
suspect, or the radio aid fails;


GEN 3.3 para 3.6 and 3.7:

3.6 An aircraft must not be flown under the IFR, lower than the published lowest safe altitude or the lowest safe altitude calculated in accordance with this section, except when being assigned levels in accordance with ATS surveillance service terrain clearance procedures or when being flown in accordance with a
published DME arrival, instrument approach or holding procedure,or except when necessary during climb after departure from an aerodrome, or except during VMC by day (CAR 178 refers).

3.7 If the navigation of the aircraft is inaccurate, or the aircraft is deliberately flown off track, or where there is a failure of any radio navigation aid normally available, the area to be considered is a circle centred on the DR position, with a radius of 5NM plus 20% of the air distance flown from the last positive fix.



So putting this all together:

1. A radio NAVAID required for the approach has failed (and GPS can't be used in lieu due no RAIM) so a Missed Approach must be conducted.

2. As no longer flying a DGA, must remain above LSALT/MSA until arriving overhead the fix or facility (the Parkes VOR in this case). Note you don't need to fly the entire missed approach (ie you don't nee to fly to the overhead then track outbound), just get above LSALT/MSA then continue IAW GEN 3.3 para 3.6.

3. Even though you had fixed yourself inside 14nm (at 12DME when DME failed) there is no provision in the regs to continue using what is effectively a lower route LSALT within 14nm of 3500ft. A NVFR aircraft can use a lower route LSALT once a critical obstacle has been passed, but this must be determined by a visual positive position fix, and doesn't apply to IFR -I just include this in case there's some confusion about using a lower route LSALT once fixed beyond a limiting obstacle.

So while I would argue that provided you remain within tracking tolerances towards the PKS VOR you would still have 1000ft obstacle clearance if you descended to 3500ft, the AIP references quoted require you to get above the LSALT or applicable MSA. At 12 DME (now your DR position) you need to consider a distance out to 17nm, which still puts you within the 25nm MSA so you'd need to climb to 3900ft. If you were at 8 DME you'd still need to go to 3900ft because of the 5nm tolerance.

A real "technicality", hence a great IREX question. I must admit that personally I'd have no issue continuing at 3500ft as I'd be happy I had the required terrain clearance, but the regs don't permit it. I don't know how many IFR pilots placed in this position would recall the requirement and actually climb as they'd be fairly happy that they had the required obstacle clearance (admittedly I'd have been one of them until I double-checked AIP). Great timing as I have a CIR(H) ME renewal this week. Also a good question for my trainees...

Congratulations on the IREX pass too -not an easy exam, though that's probably more to do with misreading the questions and technicalities like the question above. I did my IREX about 8 years ago, have been instructing IF in helicopters reguarly for the past few years, and still there are things to learn -subtle nuances like the question above. My point being that the IREX (like most ratings) is a licence to learn. It takes a while to get on top of the regs and completely understand them (obviously I got a step closer today, but I'm not there yet!). Now you've got the IREX keep the knowledge up -if you're not using it you're losing it! If you're not in a position to fly and apply IF, find some folks to pose questions to (Bladeslapper ain't that bad a place for that...). Another way to test your knowledge is the quiz in the back of CASA's Flight Safety magazine: not helicopter orientated, but neither is the IREX! I heard a statistic once that a third of pilots who sit the IREX pass first time, another third take several attempts, and the remaining third never pass. Assume it's true, and consider yourself in good company.

From here I'd recommend downloading a copy of CASA Form 645 (Instrument Rating Assessment) and putting together a study guide for the Pre-Flight Examination. You will get quized on all items for an initial issue (and a renewal depending onthe ATO) and any KDR items from the IREX. The IREX pass is the first step: you need to demonstrate a practical understanding to the examiner when the time comes.

All the best with the next step in your training!

PD

[skypig]

pavlov's dog (1.at least he was well fed. 2. great old band)

Well said mate - great use of Bladeslapper

Link to form 645 http://www.casa.gov.au/wcmswr/_assets/m ... orm645.pdf

sky "Renewal comming up" pig

[Jabberwocky]

Thanks for that pavlov's dog. It's a great help for us newbies to have someone show us their answers to the Casa riddles like that.

[pavlov's dog]

Thanks guys, but no guarantees I'm right!!! (Think I am but! )

PD

[UnObvious]

Knocked out ATPL Air Law within the last few days also, and I had a question in regards to a pilot electing to discontinue the approach before reaching the Mapt. The correct answer (and the answer I put) was "continue to the Mapt, climbing as required, and carry out the published missed approach procedure."

So PD, I think you're on the money.

Watch for a post on what to study for the air law exam!