Time for flight is wrong... really wrong...


#1

flightaware.com/live/flight/ACA29

Look at this flight, which goes from Vancouver to Beijing. It takes about 11 hours, and not the 4 hours shown, because one end is shown as PST and the other end as GMT, which are 7 hours apart in time zones, and the program is treating them as the SAME time zone. Thus the error. The aircraft is taking off on Monday afternoon Vancouver time and landing Tuesday afternoon, Beijing time… 12:40pm PST to 4:05pm Beijing time is NOT 4 hours and some minutes. Note must be taken of the different time zones or the figures shown will always be wrong. :frowning:

I know this one because my son just got married and they are on this flight as the first part of their honeymoon, and your tracking of it is almost useless to me… but the time is a hoot…


#2

Unfortunately we don’t have a list of timezones for airports worldwide, so for airports outside the US and Canada we display the time in GMT.
The flight departs US observed airspace after about 4 hours, so we no longer have any tracking data for it after that time. For any further updates you’ll have to go to the airlines website.


#3

Your response does NOT address the problem you have or that I am reporting, since use of GMT is just fine and would NOT prevent you from correctly calculating the estimated flying time.

If you post the time for Beijing in GMT and the time for the flight in Vancouver as PST, that still permits you to calculate the total scheduled flight time correctly, but you are not doing that!

There are 7 hours difference between PST and GMT, and the flight itself shows a time of 4 hours and x minutes, so since the flight is heading WEST you ADD the 7 extra hours to the 4 hours and 52 minutes to get the correct ESTIMATE of 11 hours and 52 minutes SCHEDULED flight time.

It has nothing to do with the failure to have the correct time zone for Beijing… It has EVERYTHING to do with what you are saying is the scheduled flight time, which is WRONG, and there is NO excuse for that error, since you do NOT need the time zones for those airports not in the US or Canada.

For the airports in the US or Canada, use GMT as THEIR time for all your calculations and you will always get the correct total estimated travel time since the time zone changes will be eliminated from the computation!

Convert the Vancouver time to GMT and THEN calculate the estimated flight time. You will get the correct travel time in the air, since both airports will be using the same time zone for the start and end of the flight. Just make certain you correctly account for the DIRECTION of travel, which in this case is WESTBOUND, across the international date line.

Or build a simple table, Beijing is at +8 hours to GMT while Vancouver is at -7 hours to GMT, so the difference is, going west, 9 hours in time zone changes and going east it is 15 hours in time zone changes, and you could still calculate the scheduled trip time correctly.

The aircraft leaves Vancouver at 19:40GMT and lands at 8:05GMT the next day. so we add 8 hours and 4 hours and we add 5 minute and we add 20 minutes and we get an estimate of 12 hours and 25 minutes between departure and arrival, and NOT the 4 hours and 50 odd minutes you show on your site as the ESTIMATED flight time!

Do not bother telling me why the above cannot be done, since you already have ALL of the time zone information you need even if you do NOT know the correct time zone for Beijing.

RsH


#4

Hi, RsH.

The international flight tracking support is working pretty much exactly as described in the FAQ, although it references the US; perhaps it should refer to North America although we don’t guarantee the entire service area.

There is no confusion on our side about how time zones work. As mduell said, we currently don’t support display the local time for international airports, so we use GMT. Internally, all times are stored as GMT and as a result, all calculations and estimations are based on this unified time zone.

Daniel


#5

RsH,

The flight duration is being calculated correctly, but what we list as the arrival time is the time that the flight leaves US/Canadian airspace. When that occurs, we receive a cancellation or arrival-like message and mark that as the arrival time. We currently have no way to determine the aircraft’s arrival time in China.

Mark


#6

Easy there! No need for temper.

I, for one, would much prefer that the Discussions Forums be used in a constructive, civil manner to exchange information and ideas and not bashing the programers because their FREE service doesn’t work quite like one wants it to.

Every one of the thousands of FlightAware users would probably like to see some thing or another a little differently. It doesn’t make much sense to get ticked off at the programers because the UNITED STATES FAA doesn’t report information for arrivals in another country. I’m sure that the airline’s web page will report the arrival information since that’s one of the services that a ticket-holder is paying for.

This is by far the best site of it’s kind on the web. They are doing an awsome job. It’s a daunting task to keep things straight that are happening in the US. To keep the whole world on time might be asking too much. A list of the worldwide time zones is completely moot. It should be obvious that FlightAware cannot show arrival time for any flight that it is no longer tracking, whether within the US or without. Once it leaves US airspace, who knows where it is being vectored, slowed down, sped up, deviating for weather or any of the other factors that affect actual arrival time vs. planned arrival time.

Sincerely,
BTaylor, a happy FlightAware user who will NOT be asking for my money back!
NOTE: Opinions stated are my own. I have no affiliation with FlightAware, nor do I even know any of its staff.


#7

Have to echo BTaylor’s sentiments; realise the limitations on tracking - we get no updates for a/c to Europe once out of FAA range and sadly UK tracking was withdrawn from us a while back but at least I know some thing is on its way and can use a more realiable source (airline/aiport web page)to check arrival if it is important.
Note, many US a/c in country losing the tracking if they canx IFR plan and elect to go visual to destination. How can that be updated if no updates received, what chance China??
GMT is a universal time language for aviation, easy for Brits cos’ the differences are not great but with different time zones…well many good web time zone convertors available to help.

keep up the very good work FlightAware, another happy customer here.

IN (uk)


#8

Wow. RsH has some issues. Maybe he knows exactly how to do it and should do it himself. Good Lord - that was totally unprovoked.

You guys are doing a great job. Some just don’t understand the limitations of the data. It would be nice to be able to tell where a flight is anywhere in the world at anytime, and it’s only a matter of time before we have satellite based transponder tracking to supplement the radar tracking, but until then, be happy with what we’ve got. I for one am, plus, remember, it’s FREE. Can’t beat that.


#9

Not quite satellite tracking but any of you guys in the States playing with one of these?
kinetic-avionics.co.uk/basestation.php

Virtual radar from the comfort of your lay-z-boy!
IN(uk)


#10

Actually, sir, it’s 8 hours difference between GMT and PST. Or are you talking about ZULU time?

Right now it’s like this…

Eastern = ZULU - 5
Central = ZULU - 6
Mountain = ZULU - 7
Pacific = ZULU - 8

Of course is GMT the same as ZULU? I’m not sure. If GMT moves its clocks for savings time as we do in the US then the answer is “No” as ZULU NEVER EVER EVER EVER changes its “clock”.

Course if these flights are departing in Arizona or Indiana (minus the 6 or so counties in Western Indiana that DO change their clocks) then they throw a monkey wrench in it as Arizona and Indiana don’t change their clocks…well, actually Indiana just voted to do so…when that goes into effect I’m not sure.

So, since they’re “polling” the FAA’s computers for the information and the FAA references LOCAL time always (why b/c I want to know what time I have to leave MY house to catch MY flight at MY right time…not in reference to the rest of the world)…it’s a BIT more complicated than you think and perhpas you could tone it down and suggest a bit NICER that maybe they look into a way to correct this for the THOUSANDS of flights.

So far you’ve found AN example…and it tells you that it doesn’t handle International flights very well in the FAQ’s…that you SHOULD have read.

So, perhaps for a free service you could chill it out a bit…“simmuh dan nah”…and be happy with the what 99% success rate here.

Or, as you’ve illustrated so well…do the math in your head if you wanna know that badly.


#11

Our feed from the FAA actually states all times in UTC and we convert to local or your preferred timezone from there.


#12

Either way…you’re doing you best…the main point I wanted to get across.


#13

For common usage, “GMT” is simply a deprecated term for what is more properly called “UTC” these days and it is indeed the same as “ZULU”. When most people say “GMT” they are referring to UTC – Coordinated Universal Time. And you are absolutely correct, PST is eight hours behind UTC. During Daylight Saving Time, the Pacific timezone is in PDT which is only seven hours behind UTC. Neither GMT or UTC or ZULU (the same for all practical purposes) observes any form of Daylight Saving or Summer Time.

Stop reading here if you just want to understand how FlightAware reports time. What follows is boring unless you’re miserably curious about how time is measured in excruciating detail… :slight_smile:

Just about any civilian or military time system you might encounter (including the times used for GPS tracking and our FAA data) is UTC-based. If you’re an astronomer, the small difference between UTC and GMT is more meaningful.

GMT runs slower than UTC as it is derived from astronomical sources (and not synthetic sources like an atomic clock). Since the rotation of the earth is slowing over time, this results in GMT running just a little bit slower than UTC time, so periodically leap seconds are introduced into UTC to keep the two systems in sync. We’ll actually have a leap second next month, the first one since 1998. That should give you some idea of the scale of difference between UTC and GMT, too. One second in seven years.

For most practical and legal-trade purposes, the fractional difference between UTC and GMT is inconsequentially small, and for this reason UTC is colloquially called GMT sometimes, even if this is not technically correct.