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Publications / Frequently Asked Questions (FAQ)

This collection of frequently asked questions (FAQs) provides brief answers to many common questions about aviation products and service, and this website.

It also provides links to more detailed information available from this web site. Please check here for answers before sending us an email. However, if you have trouble finding the information you need, please let us know through the Feedback option.

Table of Contents

General Questions

Browser, Monitor, Printer Settings




Aviation Meteorology

Cellular Phone, Blackberry, XM radio access

General Questions

Why do I have to use at least seven characters to define my user password?
This is a security feature of this website.. A seven character password ensures a certain level of security. To make your password easier for you to remember, we recommend that you use your pilots license number. Additionally, we will ask you to fill in the Password hint field. In the event that you forget your password, this information will make it easier for you to remember it.

Browser, Monitor, Printer Settings

The data is old. How can I get current data?
The next time you obtain weather information that is out of date, try clearing your browser's cache. The cache is a computer memory with very short access time used for storage of frequently used instructions or data. Clearing the cache will allow your computer to retrieve new data, and this usually fixes the problem. If you do not know how to clear the cache, follow these instructions:

For Mozilla Firefox
1. Go to <<Tools>>
2. Select <<Clear Private Data>>
3. Make sure <<Cache>> is checked
4. Click the <<Clear Private Data Now>> button

For Explorer
1. Go to <<Tools>>
2. Select <<Internet options>>
3. Select General Settings tab
4. Click on <<Delete Files>> in the Temporary Internet files section
5. Go to settings, and make sure that the browser is set to "automatically" check for new versions of stored page

Or, as an option, once you have the information that you requested you can click the Ctrl + Alt + Refresh button and your request will be re-submitted to the server and the most recent information will be made available to you.

How can I bookmark a specific product?
Most of the products on the NAV CANADA Aviation Weather Web Site are dynamic products, which are generated on request by a user. This means that the pages are built when requested and do not reside on the machine discs. If you bookmark them you will be prompted with an error message the next time you try to access them.

You can however bookmark the product selection page using your browser's particular capability to bookmark pages.

For Windows
1. Navigate to the product selection page.
2. With your mouse, right-click over a blank space on the page.
3. Select <<Bookmark this page>>.
4. Bookmark pop-up window appears.
5. Accept or type in your own bookmark title, then click OK

If you want to rename the bookmark, do the following:

5. Left click on the bookmark menu.
6. Select <<bookmark name>> from list.
7. Right click on the link.
8. Go to bookmark properties.
9. In the <<Name>> box, type in the name you want, or leave the name that appears by default.
10. Click <<ok>> and close the window. You can now access the page through the <<Bookmarks>> menu.


1. Navigate to the product selection page
2. Go to the Favourites tab and choose "Add to Favourites". This action will add the URL to your list of favourites.
3. Alternatively, right click somewhere on the blank area on the product page.
4. Select <<add to favourites>>.
5. By right-clicking the item in the Favourites menu, you can use the "rename" function to change the title of the item in your favourites menu.

For Mac users

For both Netscape and Explorer users
This section should be deleted since we officially do not support this operating system.


How do I decode a METAR or TAF?
If you are having difficulty decoding a METAR or TAF, an option "plain language" is available:

Also, if you click on the Publication tab (top right of the banner) then scroll down and click on "link for non-kiosk users", you will find several manuals for codes, symbols and abbreviations:

NAV CANADA Aviation Weather Services publishes a weather guide which you can receive free of charge. If you would like a copy, let us know via the Feedback option and we would be pleased to send one to you. Copies of this guide are also usually available at NAV CANADA Flight Service and Flight Information centres.

Why is the GFA not always reflecting the weather described in the TAF?
An aerodrome forecast (TAF) is the most probable weather conditions, within 5 miles of a given site, at the most probable time of their occurrence. A graphic area forecast (GFA), on the other hand, depicts the range of conditions that are likely throughout a large geographic domain. To have a TAF that is different than the GFA is therefore not unusual. For example, the GFA may indicate that there are isolated thunderstorms over a defined area, but the aviation meteorologist may have good reasons to believe that they may not affect a given aerodrome, so the TAF makes no mention of it. The reverse situation, however, should not occur. For example, if a TAF says freezing precipitation and the GFA does not - that would bear some investigation.

How do I obtain historical weather reports?
If you require historical weather information there are 3 potential sources:

1. Fairly recent aerodrome forecasts (TAFs) and routine aviation weather reports (METARs) are available on the following web site:

2. Older TAFs, METARs, and other weather products are available from the Meteorological Service of Canada (MSC) from one of the contacts on the following web site:

3. Generic climatology data (e.g. temperature averages) are available from the MSC's National Climate Data Archive:


What GPS NOTAM aren't available for RAIM on your website?
GPS NOTAM for 129a 129b type of GPS aren't on our website because there are no NOTAM distributed by Canada. As a consequence users need to go to to find this kind of NOTAM.(KNMH) We could have elected to add this link to our website but these NOTAM are only advisory: just a way to tell pilots "Don't forget to check your RAIM because one or several satellites are down". The NOTAM itself will not give you the RAIM. Only the GPS itself or special RAIM prediction software installed on your computer (as indicated in COM of the TC AIM) would calculate RAIM automatically. Checking RAIM on the GPS being part of checklists and the NOTAM not being very useful, we came to the conclusion that there is no great need to add a GPS NOTAM link on the website.

On the other hand, as indicated in the TC AIM, NOTAM for WAAS (TSO C145a/C146a) used for LPV approaches for example are distributed by Canada and are distributed on our website as part of:

- A particular Aerodrome NOTAM file if it is a problem affecting only a particular airport (Example: LNAV approach)

- A FIR NOTAM file if the GPS problem affects several airports

- A National NOTAM file if it affects the whole country


Can I request additional products be added to the web site?
Yes. We are open to suggestions and ideas.

The satellite images are black. What's wrong with them?
Have you ever come across a satellite image that looks like this, and wondered what was wrong with it?

This phenomenon occurs with visible satellite imagery, either at night, early in the morning or late in the evening, when light levels are too low to produce a clear image over some areas. Rather than showing an image with no detail, the affected sections are shown as black. In the morning, the black area to the left of the image will disappear. In the evening, it will appear from the right. This phenomenon does not affect infrared imagery, which can be used 24 hours a day.

Why there are only 28 airports in "Live RVR"?
This is temporary. We are planning to display all RVR sensor equipped airports in the future. The reason for this limitation is that there are 2 kinds of equipment in the country and it is more difficult to link and retrieve the data for a web based application from one of them.

Why is the AWOS AUTO observation sometimes different from what the Weather Camera (Wx Cam) shows?
This is because the AWOS ceilometers "shoot" straight up over the airport. Therefore AWOS represent the weather at the airport itself not the environment away from the airport. This why the TAF should always be consulted. Eg:

Why aren't GFAs and SIGMETs available in plain language?
It is because these bulletins are already written in abbreviated English. If you have problems with the abbreviations used in those bulletins, click on the Publication tab (top right of the banner) then scroll down and click on "links for non-kiosk users", click the MANAB hyperlink. MANAB is the manual of abbreviations used by forecasters.

International SIGMETs observe the full ICAO (International Civil Aviation Organization) format, which means that the text they contain is written out in full English, i.e. no abbreviations are used. An example of an international SIGMET is given below:

WSCN02 CYUL 100135
CYUL SIGMET A5 VALID 100135/100535 CYUL-

Can I get access to American data?
Yes. There are 2 buttons at the bottom of the Forecast and Observations page for American data: one for weather, the other one for Weather cameras.

Why Route Data is only available for Canada? Will I eventually be able to get Route Data for US destinations on this website?
It is our goal that a homogeneous suite of products and flight planning capabilities be available across North America. At the present, however, NAV CANADA doesn't have a robust means of ensuring that all US Weather data is current and that routine Data base changes to American site names and hours of coverage are being received. Until the telecommunication infrastructure can be put in place to reliably receive and process this type of information, US Weather will be available only via a link to their ADDS website: please click on the buttons at the bottom of the Forecast and Observations page to access it:

When I request an image or a chart on the website, why does a hyperlink appear? Why doesn't the chart or image appear immediately, instead of the hyperlink?
Usually, our web site users request charts and images in addition to textual forecasts and observations. When the <<Submit>> button is selected, all of the products the user has requested are generated at the same time, i.e. textual products as well as charts and images. In order to ensure the information requested downloads as quickly as possible, we have opted to present hyperlinks to all requested charts and images, instead of the actual image/chart. This ensures our users obtain most of the requested information as quickly as possible. If, however, you request only a single chart, then the chart will be displayed directly.

Aviation Meteorology

Where can I learn more about the rules forecasters must follow to write aviation forecasts?
If you click on the Publication tab (top right of the banner) then scroll down and click on "link for non-kiosk users", you will find a manual called MANAIR. This document is the manual of standards and procedures for aviation forecasting in Canada. This joint Transport Canada - Environment Canada document is used by all personnel charged with the responsibility of preparing and disseminating aviation weather forecast products used by the national civil air transportation system.

Where can I learn more about aviation meteorology?
This website contains most of the aviation weather information pilots need to plan a flight, as well as links to other aviation weather products and publications from Environment Canada (EC) and the National Weather Service (NWS). To obtain additional aviation weather information, use the EC website at, and the NWS website at

Additionally, aviation weather publications are available from Transport Canada at or 1-800-305-2059.

Where can I find historical weather conditions?
The official archive for weather products and data is the Meteorological Service of Canada (MSC) - Environment Canada. You can find their Climate Data Centre and Archives on line by accessing the MSC website

Cellular Phone, Blackberry, XM radio access

Why can't I access the website through my cellular phone or Blackberry?
We need to work on making the data more accessible to telecommunications means such as PDA's and cell phones. This kind of access is in our plans of improvement in the concept of operations for the next major re-write of the website.

Why can't I access Canadian weather through my GPS?
Nav Canada has offered to conclude a licensing agreement with a satellite radio service provider. The choice to actually offer an aviation weather service via a satellite radio subscription will then be up to the company involved.

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Weather data provided by Environment Canada and NAV CANADA