IFR question (Aerocourse Workbook 6th edition (a))

[ETOPS]

I'm at a bit of a loss regarding question 81 in the Flight Planning & IFR Procedures section.

The answer in the back makes reference to the following TAF:
TAF CYWL 151630Z 1517/1605 26015G25 3SM SN FG OVC010 PROB40 1520/1523 2SM SN FG 0VC007

First of all, is 0VC007 a typo for OVC007, or is it really "zero"VC007?
If its not a typo, how does one interpret "zero"VC007 (I'm aware VC stands for vicinity)?

The question asks about the suitability of Williams Lake as an IFR alternate at 2000Z.
The YWL plate provided as reference is for NDB RWY 29 (GNSS).
That means there is only non-precision approaches available and therefore the alternate minima should be 800-2.
So why is Williams Lake a suitable alternate at 2000Z? Does the GNSS overlay count as a precision approach?

Anyway, the answer may very well be staring me in the face and I'll probably look rather dumb for asking this...oh well.

Thanx in advance.

[Typhoon]

I'm at a bit of a loss regarding question 81 in the Flight Planning & IFR Procedures section.

The answer in the back makes reference to the following TAF:
TAF CYWL 151630Z 1517/1605 26015G25 3SM SN FG OVC010 PROB40 1520/1523 2SM SN FG 0VC007

First of all, is 0VC007 a typo for OVC007, or is it really "zero"VC007?
If its not a typo, how does one interpret "zero"VC007 (I'm aware VC stands for vicinity)?

The question asks about the suitability of Williams Lake as an IFR alternate at 2000Z.
The YWL plate provided as reference is for NDB RWY 29 (GNSS).
That means there is only non-precision approaches available and therefore the alternate minima should be 800-2.
So why is Williams Lake a suitable alternate at 2000Z? Does the GNSS overlay count as a precision approach?

Anyway, the answer may very well be staring me in the face and I'll probably look rather dumb for asking this...oh well.

Thanx in advance.

I'll try give it a shot for ya. I think 0VC007 is a typo for OVC007. Secondly, GNSS (overlay) approaches are not considered precision approaches, but I think they provide lower minimums than standard non-precisions (I think usually down to 250ft AGL).

About your alternate min question, because the weather in the original forecast (vis of 3sm and ceiling of 1000 which is above 800-2) is suitable to hold it as a alternate you can use it as an alternate for 2000Z. This is because (I don't have the plate infront of me so I can't see the landing mins) the rule for PROB30/PROB40 is that this weather needs to be above LANDING mins, not ALTERNATE mins, therefore the 800-2 rule does not apply for the PROB40 section of the forecast, only the landing mins.

Hope that helps.

[sakism]

TAF CYWL 151630Z 1517/1605 26015G25 3SM SN FG OVC010 PROB40 1520/1523 2SM SN FG OVC007

It is OVC007 - overcast 700'. The zero is definitely a typo.

Alternate minima is 800-2. This works because the forecast is 1000-3.

The 700-2 is a PROBABILITY. If you read the CAPGEN carefully, you will note that when using a TAF, weather forecast as a PROB need only be greater than the Landing Minima NOT Alternate Minima.

I don't have the plate in front of me, but if the answer says it works as an alternate, then I can only assume the landing minima is less than 700-2.

Typhoon beat me to the punch.

[ETOPS]

Ahh, there it is!
I read (several times) the exact line in the AIM, and the landing just did not register...

Thanks for the quick response guys.