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Use of "Time Filed" in the Preamble

posted Apr 17, 2019, 5:23 PM by C. Matthew Curtin
On this evening's net, Gene N8YRF raised an important issue on the use of the (optional) Time Filed element of the Preamble of the Radiogram. He commented that it is not generally used for Routine traffic but is used during Emergency and Priority precedence traffic.

Emergency and Priority traffic are to be handled with particular urgency, so the time of day in that case is generally quite sensible to include.

As with most amateur radio nets, COTN's call-up begins with identification of the net and a call for stations with Emergency or Priority traffic. In the event that we have someone list such traffic, we'll handle it immediately—even before the rest of the net call-up. (Note MPG 4.6.3, "Listing Formal Radiograms" says that Emergency traffic is to be declared and handled immediately by any means necessary.)

In the event that either Emergency or Priority traffic is brought to the net, Net Control will call for another station on frequency that can handle the traffic and wherever possible move the stations to another frequency to handle the traffic while the rest of the net call-up takes place. Once traffic has been handled, stations will return to the net frequency and advise net control that they're back and therefore ready for additional business.

In addition to the case of Emergency and Priority traffic, there is the matter of handling instructions B (HXB). HXB is followed by a number to indicate the number of hours that the message is to stay alive. For example, HXB 36 means that the message is to continue moving toward delivery but if delivery has not happened 36 hours after Time Filed, the message is to be canceled and serviced back to the station of origin.

Finally, it's important also to remember that when using Time Filed, you need to ensure that the time is correct. Standard amateur practice is to use universal time (UTC, also known as Zulu time) to ensure that the time is unambiguous through timezones. Hence, something filed at 1200 APR 17 would be 8:00 A.M. eastern daylight time, which is four hours behind UTC. If local time is to be used, amateur practice is to use L at the end of time filed, e.g., 0800L. A timezone designator is also allowable, e.g., 0800EDT. UTC is preferable.

For additional information, please see Chapter 1 of the MPG, specifically 1.1.7, "Time Filed, [TIME], Optional."
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