Monday, December 08, 2008

Changing Weather

Recently when I pulled up the TAFs on my computer I had a surprise. Тhe format of the coded aviation forecast was a little different.

TAF CYUL 020238Z 0203/0224 21010KT P6SM BKN025 BKN040 TEMPO 0205/0209 6SM -SHRA BKN020
BECMG 0208/0209 22017KT
FM020900 22017KT P6SM BKN025 BKN040 TEMPO 0209/0212 3SM -SHSNRA
FM021200 24020G35KT P6SM OVC015 TEMPO 0212/0218 3SM -SHSN SCT015 BKN030
FM021800 25020G30KT P6SM BKN030
RMK NXT FCST BY 020600Z=

I'm used to subtle changes from region to region. Even though there is a nationwide standard, itself a subset of the international standard, individual stations and centres develop quirks based on the preference of the old guy that the newbies copy. For example, many places in Canada have variable direction winds, but there's only one place I can think of that frequently uses the codes to show the amount of variation. But this TAF change is a big difference, not a little quirk. I suspected a nationwide change.

Previously that would have been coded like this:

TAF CYUL 020238Z 020324 21010KT P6SM BKN025 BKN040 TEMPO 0509 6SM -SHRA BKN020
BECMG 0809 22017KT
FM0900 22017KT P6SM BKN025 BKN040 TEMPO 0912 3SM -SHSNRA
FM1200 24020G35KT P6SM OVC015 TEMPO 1218 3SM -SHSN SCT015 BKN030
FM1800 25020G30KT P6SM BKN030
RMK NXT FCST BY 06Z=

Those who don't know how to read TAFs are probably laughing at me calling it a big difference. But there's a meaning to standard and that is that one guy doesn't get to use a slash when someone else isn't. I checked other regions to see if the change was everywhere. And it is. Here's Winnipeg.

TAF AMD CYWG 020428Z 0204/0224 19020G30KT P6SM BKN050 OVC070 TEMPO 0204/0207 1SM -SNPL VV006
FM020700 20020G30KT P6SM SCT070 TEMPO 0207/0212 P6SM -SN BKN040
FM021200 28020KT P6SM OVC030 TEMPO 0212/0224 3SM -SHSN OVC015
BECMG 0216/0218 32025G35KT
RMK NXT FCST BY 020600Z=

I could see the difference of course: the old validity block 020324, meaning valid beginning the 2nd day of the month at 0300z up until the 2nd of the month at 2400Z was being made more explicit with the day of the month specified for both the beginning and ending time: 0203/0224. Up until now pilots have been considered smart enough to figure out that a validity of 022206 meant that the first time was in on the 2nd day and the second time on the following day. It's kind of like if you're told "we're having a party on the 2nd of March, from 8 pm to at least 2 am, so drop in any time." You know not to turn up at 2 am on the 2nd of March. Clearly the 2 am being referenced is very early on the 3rd.

But why were they changing it? If anyone believed that people were having accidents because they couldn't tell what day the TAF was for, either they or the accident-prone people were probably attending 2 am parties before making decisions. And if they were going to change that for clarity, then why not make other obscure parts of the TAF clearer? And how do you offset the risk to people who are used to the old codes and make errors because things are being rearranged on them?

I checked the amendments in the latest AIM issue and sure enough it tells me:

Effective November 5, 2008, the format of the Canadian TAF will be modified in accordance with Amendment 74 to ICAO Annex 3, to extend the validity period to a maximum of 30-hr. To accommodate this extended validity period, a two-digit date will be added to all times in the TAF.

So TAFs might someday cover thirty hours instead of the twelve or twenty-four they cover now. That makes sense. Curiously, Vancouver seems to already have a longer TAF. The last two issued have begun:

TAF CYVR 020240Z 0203/0306
TAF CYVR 020538Z 0206/0312

That's twenty-seven and thirty hours, respectively. I suppose that's for flight planning in long flights from Australia and New Zealand. Recent accidents for Qantas and Air New Zealand have nothing to do with trans-Pacific weather, but the latter is shocking enough to be worth mentioning even on such a poor segue. The NZ articles contain some of the most ridiculous aviation speculation ever written, but some basic facts are there, and a picture. I'll probably do a post on it when more information is available.

19 comments:

syrad said...

When our company briefed us on the change we were told the reason was indeed to assist in planning of long-haul flights.

Head in the Clouds said...

I typically use KIAD (Dulles) to check the local weather since JYO is only about 8 miles away... and they have started using the 30 hours TAF. AOPA had a big article on it-- which said it was for long-haul flights. But it's awfully nice for getting a quick picture for upcoming short flights, as well.

Samwise said...

Just as a datapoint, we in Finland had the corresponding change also. At the same time, TAFs for major airports changed from 24 hour to 30 hour validity periods so the need for the slash notation was kind of obvious.

Took a little getting used to, though..

mingduc said...

I've been reading these coded messages for many years and still don't see the point. It seems to have become some kind of on-going pilot IQ test. Or they're like a "fit-to-fly" barometer. As in - I can't make sense of this jibberish today, guess I should of booked off!

This ultra-compact language was derived in the days of the teletype when every character cost a fortune and took ages to transmit. That we are still working with them in the 21st Century "information age" astounds me.

Every step they take to make the things read more like plain English is a bonus - I wish they'd do more. But then think of how many puzzling questions they'd have to replace on pilot exams!

Just nonsense imho. Plain language forecasts and reports puleeze!

Anonymous said...

mingduc ...

sure, but once you're used to them, what a compact, consistent presentation.

Try scanning a list of METARS and contrast with a list of english equivalents.

And if its a secret language, so be it. P6M SKC 2 you too.

Aviatrix said...

It seems to have become some kind of on-going pilot IQ test.

1) When you have to read forty of these things before a breakfast meeting at which you will discuss the day's work, or read a printout off your clipboard in the dark, while flying an airplane with no autopilot, the compact and invariable form is very useful. You never have to skim text, you look you see the period you want and it goes straight to your brain. Asking for it to be otherwise is like asking the VOR to be replaced with a scrolling message reading "... bit to the left, okay good, hold that heading ... now right, too much ..."

2) If you fly infrequently or are accustomed to having your weather filtered through a briefing from a dispatcher, and have not internalized the codes, then by all means click the radio button to see the plain text version.

Aviatrix said...

And a high-five to Anonymous for monobraining. :-)

dpierce said...

The coded format is also language independent and can be easily machine read.

Anonymous said...

Plain-language for YOU, sure! For ME? No, thanks! A 2-hour flight with an alternate already yields almost 2cm of paper at my flying job.

The new format caught me off-guard and it's been hard to get used to, surprisingly. Old-dog effect, I suppose.

nec Timide said...

I find I can't easily read the 'plain language' METARs and TAFs. Since they are just phrase substitution for the code they don't scan like plain language. For those who find the code difficult to digest, NavCanada has the Flight COND page which presents a map of Canadian reporting stations in Red (IFR), Yellow (Marginal VFR) and Green (VFR) for the whole country, or by region. You can view the METARs or step through TAFs at 6 hour increments to get the big picture. If I'm planning a cross country I start there, then look at the GFAs then the text products. You really need to be able to read the code though, or the GFAs aren't as useful as they could be.

prepe said...

Ironic ... most are defending this ultra-compact coded format as if it's handy, but at the same time the topic of the blog is what a shock it is to adapt to a tiny change.

Surely simple compact Aviation words or even graphic symbols arranged in tables or some standard format can be devised that our minds would absorb even faster without having to 'dig in' and decode.

Aviatrix said...

I smile, prepe, because those ARE simple aviation words and symbols and they ARE arranged in a table of sorts. (I just fixed the formatting: there's an odd bug in the blogger that sometimes strips br tags when I use the preview function more than once and I didn't notice that it had until now).

Are you wanting SN RA PL SCT or the like to be written out in full? Why would anyone want to see or write "thunderstorms with rain and hail" when "TSRAGR" conveys the same information and is more fun to say. "Tssrahgar" -- you can hear the thunder and the hail. Do you want them replaced by graphics? I'm leery of that, because I have a lifetime of experience in reading different fonts of capital letters, and of writing them, so I'm confident I can read any worldwide TAF, and probably even read it if my crewmate scribbled it on a piece of paper. I'm not confident I could read my crewmate's "snow" and "hurricane" symbols. Heck, I'm not sure I could tell my own apart.

As Anonymous of 4:57 said, by all means make plain language available to those who can't or won't learn the codes, but don't take the compact version away from those who use it.

It's analogous to having menus and keyboard shortcuts on a computer program. A plain language only TAF would be like the Telus voicemail menu, which forces you to listen to all the prompts instead of just pressing keys in a sequence you know.

daitem said...

Pitman Shorthand! We all remember Pitman Shorthand - right? ;-) Or maybe Greg Shorthand is more popular now?

This would actually come in handy for copying IFR clearances too! And best of all - it would give pilots marketable skills for when we get layed off!! Yeah baby!

nec Timide said...

The other advantage to the coded form is language neutrality.

Aviatrix said...

Does Pitman shorthand have single character symbols for "cleared direct" "airport" "flight planned route" and "expect further clearance"? Aviatrix shorthand does.

betingle said...

Aviatrix will have to publish her shorthand so it can become standardized. non-html .grin.

Not to beat a dead horse - but I just recalled that when I started flying our aviation weather DID use symbols for overcast (circle with a plus); broken (circle with two vertical lines); and scattered (circle with one vertical line).

I can only guess that the teletype machines handled these okay? Had these built in? Anyway, I think they were dropped with computerization because the computer keyboards did not have them - is that right?

Wow - mega-shock to the system!

I'm being facetious because I often think that we pilots are the most technologically advanced group of folks around and yet we are amongst the most resistant to changes in our ways of doing things once we've "bought in." And usually for good reason.

Aviatrix said...

betingle They did indeed use circle symbols for obscuration. The shock to the system is not on the part of the pilots who no longer receive such symbols in weather reports. It's on the part of the young FO, the first time the captain copies the ATIS and then hands it to him to look at. What are these blobs? You learn the old captain's shorthand, and as much else of what the old captain ever learned that you can.

Remember: we still learn Morse code. There are very few aviation skills that have become obsolete. I wonder if I have a reader old enough to have tuned a DF. Not an ADF, the precursor?

dpierce said...

I could make a nerdly analogy about learning computer keyboard shortcuts to gain efficiency savings over friendlier mice and pull-down windows; or how using that "cryptic" command line can sometimes allow you to do something in a minute that would ordinarily take 15. But I'll refrain.

There's a lot of 'shortcuts' we have to learn in life. Nobody would suggest typing out "Queensland and Northern Territory Aerial Services"; once we all learn the acronym, we're more efficient. Shortcuts are only miserable when we use them infrequently or we have a namespace collision ("NMC? Did you mean 'Not Mission Capable' or 'Network Management Center'?").

Whether your symbology is based on text or graphics, it's been proven that once learned, our brain processes them faster than highly verbal descriptions. That can be a convenience at worst or a critical life-saver at best.

If you think about it, even words are just shortcuts for more elaborate dictionary definitions, which are shortcuts for encyclopedic information, etc. The ideal symbology would encapsulate an entire message in a single symbol, which Chinese / Japanese approaches more closely than English. It's a balance between cost of entry (ie, time to learn the system) and benefits later on (ie, efficiency in use).

Mike said...

Changing to one of the other subjects in Avi's post: The Air NZ Airbus accident had a particularly poignancy for some of us. The same day 29 years ago an Air NZ DC10 flew into Mt Erebus in the Antarctic. NZ is such a small place that it seemed like everyone knew someone on that flight. I had to go to the farm next door to try to say something - anything to the couple - to try and offer some comfort. They had bought a ticket on that flight as a graduation present for their only child, their only daughter.

And for the whole country it only got worse as Air NZ and it seemed half of those who had some power in the country sought to obfuscate, avoid, obscure and intimidate in an attempt to avoid blame. The series of investigations, reviews and findings were a serial blot on the NZ consciousness.

Sorry for the rant. It brought back memories that I would rather it hadn't.