CARS Visibility Question

[whyisitdoingthat]

Hi all,

When the CARS ask for visibility for minimum VFR operations and they mention miles, does that mean NM or SM. I've understood it to be SM, but I want to make sure. What I can't find however is a CARS reference to prove it either way.

Thanks so much

[Chuck Ellsworth]

I believe it is statute miles.

When will Canada change to ICAO format and use meters for visibility limits?

[whyisitdoingthat]

Thanks .,

From a practical standpoint it seems kind of silly for me to even care, but I'm just tweaking an ops manual and want to have some definitive stuff for the guys on the line. I'm with you on the Meters thing and hope our southern friends follow suit also since it's done pretty much everywhere else on the planet.

[Chuck Ellsworth]

One has to wonder how advanced civilization really is when we still have so many different formats to wade through just to get simple information.

We still have to read weather in code instead of plain English...and the stunning part is we are expected to use computers to access code......

I'm getting depressed just thinking about how fucked up the system really is.

[. ._]

Whaddaya mean? You can always call the AWOS that replaced the FSS guy... oh wait.

Nevermind.

[DaveC]

I'd rather use the AWOS guy than the FSS guy sometimes..

[Beefitarian]

I understand there were probably FSS guys that were so bad you would rather not have to deal with them but there is no AWOS guy. That is kind of important for the joke there.

[DaveC]

I understand there were probably FSS guys that were so bad you would rather not have to deal with them but there is no AWOS guy. That is kind of important for the joke there.

I know, it was kind of a random comment. Every time I call I get different information, all depends on the person on the other end I suppose. I've had a couple of really good ones

[Beefitarian]

The two things I miss about FSS is having a guy explain something I have never seen. "What's a xxxxxx?" and when you're some where in BC and they usually had excellent local knowledge. I did not need to be a mountain flying expert they would tell me what's up. "Don't go now, hope slide is blocked with cloud and it's really not passible."

The only thing I hate about AWOS is when you can't know what the visibility is because there's no one there to clear the sensor. Which is fine if it's reading low and you don't go zipping along into some bad weather the machine did not pick up on.

Edit: I hope I didn't sound like a jerk. Of course I am but I wasn't trying to be mean there. Sorry if it seemed like I was.

[DaveC]

The two things I miss about FSS is having a guy explain something I have never seen. "What's a xxxxxx?" and when you're some where in BC and they usually had excellent local knowledge. I did not need to be a mountain flying expert they would tell me what's up. "Don't go now, hope slide is blocked with cloud and it's really not passible."

The only thing I hate about AWOS is when you can't know what the visibility is because there's no one there to clear the sensor. Which is fine if it's reading low and you don't go zipping along into some bad weather the machine did not pick up on.

Edit: I hope I didn't sound like a jerk. Of course I am but I wasn't trying to be mean there. Sorry if it seemed like I was.

Oh no, didn't sound like a jerk just sounded like I didn't get the joke. Re-reading my response, I can see why.

I agree, sometimes they give really good information. . They er on the VERY SAFE side 99% of the time and always give you extra information (sweet ). FSS is a valuable service, no doubt.

[photofly]

I can't find a definitive statement either. But it is SM. Visibility in weather reports and briefings, and where given on instrument approach plates, are always statute miles.

EDIT: oh wait, here it is: http://www.tc.gc.ca/eng/civilaviation/p ... .htm#1-5-1

[grimey]

Yea, I doubt Canada will ever get it's shit together as far as standardization goes. Unless they've changed something in the last few years, a typical weather report from an FSS consisted of:

Cloud cover in 10ths (immediately converted to octas in a METAR... so why measure in 10ths?)
cloud height in feet
temperature and dewpoint in degrees C
feature direction (fog banks, etc) in cardinal compass points
wind direction in 10 degree increments
wind speed in knots
visibility in SM
distances in NM
pressure in hectopascals (why HECTOpascals?)
altimeter in inches of mercury

So what, nautical, SI, and Imperial unit systems all in 1 report? good job, Canada.

oh, and rvr in feet.

[DaveC]

No, what really pisses me off:

Visibility - miles
Distance - feet and miles?

Really? Is someone supposed to be able to gauge that, for distance? Might as well REALLY throw people off.

example: Distance must be 500 meters vertically and 200 feet horizontally; FUUUUUUUUUUU

Controlled Airspace
- Aircraft is operated with reference to the surface
- Visibility is not less than 3 miles
- Distance of aircraft to clouds is not less than 500 feet vertically and 1 mile horizontally
Special VFR (Controlled Airspace)
Clear of cloud, 1 mile visibility, and 500 feet above ground (only if not taking off or landing)
- Where authorization is obtained from an ATC unit, PIC may operate SVFR in a control zone in less than VFR
- All aircraft must be equipped with a radio
- Visual contact is retained with the ground at all times
- Flight visibility is not less than 1NM and is operated clear of clouds
Uncontrolled Airspace
Weather Minima less than 1000 feet AGL
- 2 SM visibility day, 3 SM visibility night
Weather Minima where aircraft is operated above 1000 feet AGL or higher
- 500 feet below clouds
- 1 SM visibility DAY, 3 SM visibility NIGHT
- 2000 feet horizontal from clouds

[Beefitarian]

Shouldn't be too hard to get used to figuring out statue miles if you fly over any prairies. The farm land is divided into sections and quarter sections. So the squares are half mile by half mile in blocks of four and the gravel roads are typically one mile apart East to West and two miles apart North to South.

Therefore if you look out the window you can see rectangles that are 1 mile by 2 miles with squares in them that are half a mile by half a mile. Then if you talk to someone on the radio or use your XM weather and it says you'll be entering 7 miles visibility soon you can look at the ground and see how far you'll be able to see when you get into that.

Dig that all up and lay out new roads in kilometers and maybe it would make more sense to use jolly olde metric for the visibility measurement.

[Beefitarian]

I think the feet for the runway thing is due to the POH and lots of 'merican's flying here. You can figure out meter possibly, most of them can not. And I am not one of these guys that hates on them and thinks they're all George Dubya dummies.

I just know if you're about to piss your pants and are crossed legged and dancing and ask where the "washroom" is the convesation ends until you figure out their word. Yet if one of them asked you where the "restroom" is, you'd point and say, "overthere." You might even say, "The sign says washroom."

[imarai]

Hmm...and your automobile odometer reads in kilometers, and you purchase fuel by the litre, yet when asked about fuel consumption, the majority of Canadians still refer to miles-per-gallon. Imperial or U.S?

Oh well, I'm off to buy a 10-lb bag of spuds as I didn't plant any this year on my acreage.

[jump154]

I grew up in a country that was practically imperial (miles, gallons, degrees F) yet officially metric - everyting I learned at school was SI units, and all my work was in SI.... I then moved to a Metiric coutry, working for a Canadian subsidiary of an American company, so everything switched around - I now live every day life in metric, yet work in inches. Some interesting converations based around differing interpretations of the term "mil". Then I started to fly, and had to learn to cope with US Gallons, Knots, SM, NM...

That's why a hot day for me is 90 Degrees, Room temperature is 71 degrees, Freezing is 0 degrees and a cold day is -25.

Learn to be flexible, double check units and convert.exe is your friend!

[photofly]

why HECTOpascals?

Because hecto- is the metric prefix for hundredth, and the pascal is the SI unit of pressure, equal to 1 newton per square metre. And 1mBar is equal to 1hPa. So the correct way to give barometric pressure in an SI unit but have the numerical part equal to the historic mBar measurement is quote them in hPa. Simple, really.

[grimey]

why HECTOpascals?

Because hecto- is the metric prefix for hundredth, and the pascal is the SI unit of pressure, equal to 1 newton per square metre. And 1mBar is equal to 1hPa. So the correct way to give barometric pressure in an SI unit but have the numerical part equal to the historic mBar measurement is quote them in hPa. Simple, really.

Yea, figured that out after I posted. Which leads to a stupider question... why does Environment Canada communicate them to the public in kilopascals?

[photofly]

why HECTOpascals?

Because hecto- is the metric prefix for hundredth, and the pascal is the SI unit of pressure, equal to 1 newton per square metre. And 1mBar is equal to 1hPa. So the correct way to give barometric pressure in an SI unit but have the numerical part equal to the historic mBar measurement is quote them in hPa. Simple, really.

Yea, figured that out after I posted. Which leads to a stupider question... why does Environment Canada communicate them to the public in kilopascals?

Because while a measurement hPa is metric, it is not SI, since hecto- is not an SI prefix. SI prefixes are multiples of 1000 and 1/1000. Environment Canada follows the SI by giving a measurement in an SI unit with the most appropriate SI prefix. But presumably they don't have any constraints about having to match the numeric part of a mbar measurement.

The whole SI thing sounds great, until you notice the SI unit of mass is the kilogram and not the gram, which rather screws up the consistency.