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Last light question

Old 27th Aug 2018, 00:53
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Last light question

This question came up in a practice exam:

Given: Planned flight time from Archerfield to Mackay is 140 min.
What is the latest departure time you can plan to depart from Archerfield to Mackay on May 27th?
  1. 270533 UTC
  2. 270513 UTC
  3. 270503 UTC
  4. 270523 UTC
The correct answer is given to be 3, 270503 UTC but that doesn't right to me.
EOD on May 27th is 0753 UTC (checked on NAIPS).
In my view, planning for an arrival 10 min before last light means landing at Mackay at 0743 UTC at the latest.
With 140 min or 2h20 min of flight time, this translates into leaving by 0523 UTC, not 0503 UTC.

Can anyone confirm or rectify my reasoning?

Last edited by Okihara; 27th Aug 2018 at 14:12.
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Old 27th Aug 2018, 01:36
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Been a while since I've done it, and currently not in a position to try myself, but what answer do you get if you use the conversion information out of the AIP?

You won't have access to NAIPS in an exam, so I'd expect you'd have to use the AIP conversion method.

I wonder if it yields a different result. Wouldn't surprise me.
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Old 27th Aug 2018, 01:54
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Originally Posted by Car RAMROD View Post
Been a while since I've done it, and currently not in a position to try myself, but what answer do you get if you use the conversion information out of the AIP?

You won't have access to NAIPS in an exam, so I'd expect you'd have to use the AIP conversion method.

I wonder if it yields a different result. Wouldn't surprise me.

Folks,
And what is the CDDP/CASA "approved" method if you are being prosecuted on a strict liability charge directly related.
Not an idle question, as you can fly in "daylight" to last light, or is the "10 minutes" "the law" or good advice, as well as such advice as effects of weather on actual light or dark.
Tootle pip!!
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Old 27th Aug 2018, 02:39
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I did the computation using the charts in the VFRG and the steps therein, and double checked the result with NAIPS.

Assuming the last light to be correct, is there any other reason that escapes me why you'd legally have to plan to land earlier than 10 minutes before that time?
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Old 27th Aug 2018, 03:15
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LeadSled, AIP ENR 1.2 para 1.1.2 b refers.
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Old 27th Aug 2018, 03:20
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CFI is correct (was typing answer when you popped it in) - it is 10 minutes plus any required holding
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Old 27th Aug 2018, 07:27
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Originally Posted by Charlie Foxtrot India View Post
LeadSled, AIP ENR 1.2 para 1.1.2 b refers.
CFI,
I am well aware of that, that or something similar, has been in the AIP for longer than I have had an Australian license. And that is quite a while.

My point was, does it have a head of power. At this stage, I haven't recently looked into the CAR, or the draft CASR Part 91.

The ICAO "VFR" has no such restriction.

It is a pre-flight requirement only, once you are airborne it is not applicable, "daylight VMC/VFR" extends to last light.

Twice now, flying aircraft that are strictly certified "daylight VMC only" I have had to do some night flying, on each occasion the circumstances were the same, the aerodrome close due a disabled aircraft as I was on final. It was at YSBK, the only available "diversion" was YSSY, I don't think I would have been too popular arriving there in the middle of evening peak, and in any event, "legal" night flying would still be involved.

On each occasion, a CASA FOI claimed that I didn't have the 10 minute buffer, on each occasion that was shown to be clearly wrong, and if they wanted to have a go at me for flying an aircraft outside the limitations of the C.of A, my address for service was: C/ XXXXXX Legal. Wider heads must have prevailed, the threats evaporated.

Tootle pip!!

PS: The legal position of ATC "holding" is quite interesting, but that is for another day, as AsA can vary that at will.
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Old 27th Aug 2018, 09:33
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Interesting point LeadSled makes about the head of power. I must admit to never having turned my mind to it, having always just assumed that the AIP had effective force of law.

A very quick look appears to support LeadSled’s position, with one rather large ... but.

you see, the Head of Power for all aviation activities has this broad section

CIVIL AVIATION ACT 1988 - SECT 20A

Reckless operation of aircraft
(1) A person must not operate an aircraft being reckless as to whether the manner of operation could endanger the life of another person.
(2) A person must not operate an aircraft being reckless as to whether the manner of operation could endanger the person or property of another person.

Now i am no QC but I would have thought that operating an aircraft in contravention the expressed and generally accepted collective wisdom (in this case the AIP - which has been around for wee while) might be considered to be reckless?

i would prefer to defend the affirmative position as defending the negative requires saying that as the AIP has no head of power, it therefore also must have no use.


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Old 27th Aug 2018, 10:05
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Okihara, just confirming, is that question copied exactly as it was shown in the exam? The devil can often be in the details for Exams!
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Old 27th Aug 2018, 10:19
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Dont use he VFRG tables for the last light questions. Only use what is published in the AIP. I’ve been told the day guide let light computation tables are incorrect.
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Old 27th Aug 2018, 10:40
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Do I read the thread correctly. You were talking about departing to go to Mackay. Then you are talking about landing at Archerfield.
Did I get it wrong or is the wording of the thread incorrect?

R16
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Old 27th Aug 2018, 11:18
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wtf isn't there a simple definition and an authorized method of calculating latest vfr landing time enshrined in simple regulation? Wtf were people thinking? simply select one definition of last light one set of conversions between civil, nautical and astronomical one method of calculating and one method of approximating. Then the earliest or latest becomes your legal planning figure.

What do the yanks do? how hard can it be?
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Old 27th Aug 2018, 11:33
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i would prefer to defend the affirmative position as defending the negative requires saying that as the AIP has no head of power, it therefore also must have no use.
You make the quite common and reasonable mistake of believing “the AIP” has a head of power.

The AIP is, in fact, a compendium of lots of disparate stuff, from aerodrome data to immigration and customs entry requirements to radio terminology and so on. Whether a purported requirement in AIP is a legal requirement depends on whether that individual requirement is supported by a specific law or exercise of a specific statutory power. I gave the example, in a different thread, of purported restrictions published in ERSA (part of the AIP) on the use of airspace around Mildura. The purported restrictions had no basis in law and were therefore removed.

To put this the other way around: Just because something is published as a “requirement” in AIP does not make it so.

I will provide an example.
174A Equipment of aircraft for V.F.R. flight ...

(1)CASA may issue instructions specifying:

(a) the radiocommunication systems; or

(b) the radio navigation systems; or

(c) the secondary surveillance radar transponder equipment;

that must be carried on, or installed in, an aircraft before it undertakes a V.F.R. flight.

[The usual criminal offence.]

(1B)If an instruction under subregulation (1) is not issued in the form of a Civil Aviation Order, the instruction does not bind a person until it has been:

(a) served on the person; or

(b) published in NOTAMS or AIP.
Note that the legal requirement to carry NAVCOM and SSR equipment on VFR flights depends on the valid exercise by CASA of the specific power to issue instructions specifying that equipment, which power is contained in CAR 174A(1). The VFR equipment requirements specified in AIP either reflect or publish those requirements, or are fluff.

To put this another way, if someone in Airservices had a ‘bright idea’ that VFR aircraft should all be equipped with signal flares and managed to get that ‘requirement’ published in AIP, the outcome would not be a legal obligation to carry signal flares on VFR aircraft. That’s because Airservices is not CASA. It would just be another Mildura ‘bright idea’ with no legal basis.

If a person operates a VFR aircraft without the equipment as instructed by CASA under CAR 174A(1) and published in AIP, that’s an offence against CAR 174A(1), not an offence ‘against the AIP’.

With that background, could you identify the provision of the law that makes it an offence not to plan on landing, or failing to land, at least 10 minutes before the end of civil daylight if flying to day VFR rules?

As you’ve cited section 20A of the Civil Aviation Act, could you identify the recklessness in deliberately planning to land, and in fact landing, 5 minutes before the end of civil daylight?

I should note that I plan to land at least 20 minutes before the end of civil daylight at my destination, and in the last few decades have busted that margin - but still in civil daylight - only once. I’m only commenting as I am allergic to folklore as well as the false legal=safe illegal=unsafe dichotomy that infects much of the shallow gene pool of Australian aviation.







Last edited by Lead Balloon; 27th Aug 2018 at 11:44.
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Old 27th Aug 2018, 12:20
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You make the quite common and reasonable mistake of believing “the AIP” has a head of power.

I did, in fact, state the exact opposite.

The rest of your post I would otherwise tend to agree with.
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Old 27th Aug 2018, 12:30
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I’ll expand on my interpretation of your words, so you can identify where my interpretation is diametrically opposed to what you stated:
[Bankstown Boy] would prefer to defend the affirmative position [because] defending the negative requires saying that ... the AIP [as an entire package] has no head of power [singular], and therefore [the AIP in its entirety] must have no use.
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Old 27th Aug 2018, 12:31
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Unless you've excluded context or misread/wrongly transcribed the full question here, I think the practice exam is wrong. Did you get it from Tait, ATC, somewhere else?
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Old 27th Aug 2018, 12:44
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Lead Ballon,

i have no intention of getting into a pointless semantics debate with you. I would only point out the following two salient facts from my post that you appear to have misinterpreted..

Firstly I acknowledged that, despite never giving it much thought before, I agreed with LeadSled’s position on the AIP having no head of power

Secondly I stated that my position was that I would not like to defend starts with the premise that “as the AIP has no head of power

if you want to believe that is me saying I do believe the AIP has a legal head of power, then I can’t help you any further.

i don’t intend to get in a slanging match, which this place devolves to far too often, so i’ll leave it at that.
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Old 27th Aug 2018, 14:03
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Great!

Could you identify the provision of the law that makes it an offence not to plan on landing, or failing to land, at least 10 minutes before the end of civil daylight if flying to day VFR rules?

As you’ve cited section 20A of the Civil Aviation Act, could you identify the recklessness in deliberately planning to land, and in fact landing, 5 minutes before the end of civil daylight?
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Old 27th Aug 2018, 14:12
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Originally Posted by runway16 View Post
Do I read the thread correctly. You were talking about departing to go to Mackay. Then you are talking about landing at Archerfield.
Did I get it wrong or is the wording of the thread incorrect?

R16
Thanks for pointing that out. It was indeed departing Archerfield to land at Mackay.

Last edited by Okihara; 27th Aug 2018 at 14:25.
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Old 27th Aug 2018, 14:15
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Wink

Originally Posted by bloodandiron View Post
Unless you've excluded context or misread/wrongly transcribed the full question here, I think the practice exam is wrong. Did you get it from Tait, ATC, somewhere else?
Thanks, I'm going to bed a little more confident that I might be right about this

The question is from a booklet with sample exams published by "Ground Effect".

Last edited by Okihara; 27th Aug 2018 at 14:25.
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