Question on calculating minimum alternate requirements

[radarbeam]

Is there there anywhere in the CARs/CAP/AIM that says that we cannot take credit for improving weather during a TEMPO for alternate calculations?

Say the alternate minima is 600-2 and our planned ETA is 22z. Can we use the following alternate? I answered YES we could because of the TEMPO but it is apparently the wrong answer because the lowest forecast during the period is 300-1.

TAF CYQY 191739Z 1918/2018 31010KT 1SM -DZ BR BKN003 OVC010 TEMPO 1806
6SM -RA BR SCT003 OVC010
FM0600Z 29005KT 2SM -SHRA BR OVC004
RMK NXT FCST BY 00Z=

I also stumbled on this link, it explains everything in detail however the author cannot provide any references to the TEMPO rule...
http://www.tompaul.ca/understand-becmg- ... lternates/

Thanks!

Edit: forgot to include the link.

[photofly]

Post again explaining how and why you're incapable of downloading the TC AIM and searching for the phrase "alternate minima" - or even using Google - and I'll tell you where to find it.

[Rookie50]

Is there there anywhere in the CARs/CAP/AIM that says that we cannot take credit for improving weather during a TEMPO for alternate calculations?

Say the alternate minima is 600-2 and our planned ETA is 22z. Can we use the following alternate? I answered YES we could because of the TEMPO but it is apparently the wrong answer because the lowest forecast during the period is 300-1.

TAF CYQY 191739Z 1918/2018 31010KT 1SM -DZ BR BKN003 OVC010 TEMPO 1806
6SM -RA BR SCT003 OVC010
FM0600Z 29005KT 2SM -SHRA BR OVC004
RMK NXT FCST BY 00Z=

I also stumbled on this link, it explains everything in detail however the author cannot provide any references to the TEMPO rule...

Thanks!

Its in the CapGen (I believe -- or in the AIM) -- but bottom line its common sense. You cannot take credit for any TEMPO improvement, as its a transitory improvement, which may not in reality be the condition when you arrive -- You also though if the TEMPO condition is worse and puts you below minimums, this also disqualifies the alternate. Essentially whatever is the worst forecast weather during the period, is the baseline that must be used.

[radarbeam]

Post again explaining how and why you're incapable of downloading the TC AIM and searching for the phrase "alternate minima" - or even using Google - and I'll tell you where to find it.

Don't worry photofly, I'm a pretty resourceful guy and I'm not looking for a free ride or to waste anybody's time. I've been going back and forth to the AIM and the CAP GEN numerous times in the past few days and the extract below is the only reference to alternate minima with a TEMPO I could find. Nothing is said about not taking credit during improving periods...at least as far as I can understand it.

3.14 (c) the forecast TEMPO condition shall not be below the published alternate minima requirements for that aerodrome

[radarbeam]

Its in the CapGen (I believe -- or in the AIM) -- but bottom line its common sense. You cannot take credit for any TEMPO improvement, as its a transitory improvement, which may not in reality be the condition when you arrive -- You also though if the TEMPO condition is worse and puts you below minimums, this also disqualifies the alternate. Essentially whatever is the worst forecast weather during the period, is the baseline that must be used.

Thanks Rookie! Makes a lot of sense indeed. However, I'm looking for the written reference on this but I can't seem to find it anywhere in the CAP or AIM.

[RamAirTurbine]

Its in the CapGen (I believe -- or in the AIM) -- but bottom line its common sense. You cannot take credit for any TEMPO improvement, as its a transitory improvement, which may not in reality be the condition when you arrive -- You also though if the TEMPO condition is worse and puts you below minimums, this also disqualifies the alternate. Essentially whatever is the worst forecast weather during the period, is the baseline that must be used.

Thanks Rookie! Makes a lot of sense indeed. However, I'm looking for the written reference on this but I can't seem to find it anywhere in the CAP or AIM.

CAR 602.123 No pilot-in-command of an aircraft shall include an alternate aerodrome in an IFR flight plan or IFR flight itinerary unless available weather information indicates that the ceiling and visibility at the alternate aerodrome will, at the expected time of arrival, be at or above the alternate aerodrome weather minima specified in the Canada Air Pilot.

Then you would use the CAP GEN and CAP to calculate your applicable weather minima and figure out all the TEMPO, PROB and BECMG.

Hope this helps!
RAT

[ahramin]

Radarbeam, your reference is the one you posted. If the TEMPO period has to be above the required minima, you're necessarily not going to find a reference allowing the TEMPO to be below required minima.

[ahramin]

I think I've figured out what you can't figure out:

1) The forecast weather must be at or above the required minima.

2) A TEMPO in the forecast weather must be at or above the required minima.

This means that BOTH 1 AND 2 must be at or above the required minima.

Or as Peter Shewring used to say: A TEMPO never helps, only hurts.

[ahramin]

Or maybe you just never actually learned what TEMPO means. If so, look it up and read it carefully.

[Rookie50]

Another related note: you can't use the improvement stated in a BCMG forecast until the very end of the period referenced -- but must use a worsening BCMG forecast immediately at the beginning of the BCMG period. Always must use the worst potential interpretation for alternate and minima planning. And yes it does happen that way, too.

[photofly]

nothing is said about not taking credit during improving periods...at least as far as I can understand it.

Indeed. Nothing is said about that, because you can't. If the underlying forecast itself is BELOW alternate minima, that's the end of the story.

[sidestick stirrer]

A hypothetical ( or maybe not) question: can you also specify your destination as your alternate?

[trey kule]

I assume you mean file to destination A, and then have your real planned destination as the alternate.
Once airborne, its off to the "alternate"

Absolutely. It used to be done routinely by the airlines..maybe still is.
0r maybe things have changed.

Suppose you want to fly to Campbell river and the weather is well above, and forecast to be above minimums to use as an alternate.
Vancouver, your real alternate is above IFR minimums but below alternate.
Easy Peasy. File to Vancouver. Cancel when airborne and head to your " alternate"

Before any one jumps down my throat about safety, fuel reserves etc etc....the question was is it legal?
The answer is yes.

On the south american runs many moons ago it was SOP to do this as there was not enough fuel to make some of the trips legally otherwise.

[sidestick stirrer]

Not quite and I apologize for the poorly-worded question.
What I meant to ask was could we file a flight plan to Airport Y and also list Airport Y as our alternate for the same flight?

[trey kule]

Your question was fine. I misinterpreted what you were asking.


Before I get any more egg on my face, I am just going to reframe from your question

[sidestick stirrer]

I don't see any egg there at all and you are indeed right.
The scenario I heard of was a pilot filed a flight plan to an airport where the forecast at the ETA was below alternate limits for that airport.
In a slow and short-ranged airplane, flying in a huge country with few airports, there wasn't any airports that he could reach as an alternate.
However, by delaying his departure a bit, the forecast for the destination improved above alternate minima an hour after the new ETA and he had the fuel to loiter for an hour to make the flight plan legal.
So it was legal, when strictly interpreting the rules. However, that is why there are Regulations and there are Standards, the latter being a working-language interpretation of the intent of the Regulation.
The rule writers never envisioned anyone distorting the rules this way and probably never felt it necessary to include language to prohibit the scenario.
We all realize the increase in risk when " putting all of our eggs in one basket" but managing risk is what we do everytime we even consider flying.
Flying so that we are committed to an airport where there is only one runway may seem pretty stupid to some, maybe even most.
Employing techniques like PofNR or being able to land on a taxiway if after the PofNR might make it more palatable.
Which brings up another question: can we land on taxiways? Can we operate from any "maneuvering area"?

[DanWEC]

You can't FILE your destination as an alternate, unless you have an permission and operating under an OC (604-705)

602.122 Except as otherwise authorized by the Minis ter in an air operator certificate or in a special authoriza tion issued under subsection 604.05(2), no pilot-in-command shall operate an aircraft in IFR flight unless the IFR flight plan or IFR flight itinerary that has been filed for the flight under section 602.73 includes an alternate aerodrome having a landing area suitable for use by that aircraft.

[ahramin]

The word alternate has a sufficiently clear definition that it should be obvious it has to be a different airport.

Is the No Alternate IFR Ops Spec still around? It basically equates to using your destination as your alternate.

[Oxi]

You'll see that in routes between yyz-yow-yul

[Cessna driver]

Is there there anywhere in the CARs/CAP/AIM that says that we cannot take credit for improving weather during a TEMPO for alternate calculations?

Say the alternate minima is 600-2 and our planned ETA is 22z. Can we use the following alternate? I answered YES we could because of the TEMPO but it is apparently the wrong answer because the lowest forecast during the period is 300-1.

TAF CYQY 191739Z 1918/2018 31010KT 1SM -DZ BR BKN003 OVC010 TEMPO 1806
6SM -RA BR SCT003 OVC010
FM0600Z 29005KT 2SM -SHRA BR OVC004
RMK NXT FCST BY 00Z=

I also stumbled on this link, it explains everything in detail however the author cannot provide any references to the TEMPO rule...

Thanks!

Its in the CapGen (I believe -- or in the AIM) -- but bottom line its common sense. You cannot take credit for any TEMPO improvement, as its a transitory improvement, which may not in reality be the condition when you arrive -- You also though if the TEMPO condition is worse and puts you below minimums, this also disqualifies the alternate. Essentially whatever is the worst forecast weather during the period, is the baseline that must be used.

Don't believe YEG's TEMPOs, 95% of the time they are wrong