ATIS at mins 20 and 50
I would imagine that maybe other important things happen on the hour and half hour, so 'they' decided to keep the ATIS away from those ?
METAR you mean? As ATIS is mainly 'event driven' not clock synchro per se (of course METAR changes force an ATIS update)
No idea, but lots of variation around the world on this METAR timing aspect. From on the (half-)/hour, to 5, 10, 15 minutes before and even variations on the minute (as in 9,8,7,... before, for example).
My guess, some historical reason, like the extremely (=as in pre-historic) low baud rate of the telex machines used long time ago in the AFTN communications network. So spreading out the timing, avoiding everybody sending at the same time, maybe??
No idea, but lots of variation around the world on this METAR timing aspect. From on the (half-)/hour, to 5, 10, 15 minutes before and even variations on the minute (as in 9,8,7,... before, for example).
My guess, some historical reason, like the extremely (=as in pre-historic) low baud rate of the telex machines used long time ago in the AFTN communications network. So spreading out the timing, avoiding everybody sending at the same time, maybe??
METAR you mean? As ATIS is mainly 'event driven' not clock synchro per se (of course METAR changes force an ATIS update)
No idea, but lots of variation around the world on this METAR timing aspect. From on the (half-)/hour, to 5, 10, 15 minutes before and even variations on the minute (as in 9,8,7,... before, for example).
My guess, some historical reason, like the extremely (=as in pre-historic) low baud rate of the telex machines used long time ago in the AFTN communications network. So spreading out the timing, avoiding everybody sending at the same time, maybe??
No idea, but lots of variation around the world on this METAR timing aspect. From on the (half-)/hour, to 5, 10, 15 minutes before and even variations on the minute (as in 9,8,7,... before, for example).
My guess, some historical reason, like the extremely (=as in pre-historic) low baud rate of the telex machines used long time ago in the AFTN communications network. So spreading out the timing, avoiding everybody sending at the same time, maybe??
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When I learned to fly in the early 80‘s I was told it was done that way to reduce load on the telex network then still used to transmit that stuff.
(I had part of my PPL ground training at an FSS-type facility where the instructor was employed. We got a short break every half hour when he typed the local weather into a teletype which in turn spat it out as a roll of punched paper that was fed into the same machine for transmission to the national weather office.)
BTW, Eastern Europe is on the 00/30 schedule.
(I had part of my PPL ground training at an FSS-type facility where the instructor was employed. We got a short break every half hour when he typed the local weather into a teletype which in turn spat it out as a roll of punched paper that was fed into the same machine for transmission to the national weather office.)
BTW, Eastern Europe is on the 00/30 schedule.
ATIS goes off air at 50 minutes and is replaced by a new one at about 55 minutes where I am based (KDVT). A runway change or a significant change in weather will result in an earlier update. At my airport it's all manual and subject to errors, such forgetting to run the new recording and using the same letter designator for two ATIS reports in a row. Mostly it's very predictable.
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ATIS is typically prepared to be "available" at the top of the hour. So often they are doing it at :50 or :55 minute mark
any WX changes or important changes will trigger a new ATIS.
any WX changes or important changes will trigger a new ATIS.
FAA AIM does not mention a specific time for ATIS update. It says -
"ATIS broadcast shall be updated upon the receipt of any official hourly and special weather. A new recording will also be made when there is a change in other pertinent data such as runway change, instrument approach in use, etc."
At KDVT a new METAR is issued at 53 minutes past the hour and the ATIS time is usually 53 minutes past the hour. I assume it is the issuance of the new METAR that drives the ATIS update which is as stated in the AIM.
"ATIS broadcast shall be updated upon the receipt of any official hourly and special weather. A new recording will also be made when there is a change in other pertinent data such as runway change, instrument approach in use, etc."
At KDVT a new METAR is issued at 53 minutes past the hour and the ATIS time is usually 53 minutes past the hour. I assume it is the issuance of the new METAR that drives the ATIS update which is as stated in the AIM.
