Seems like this might be a silly question, but in terms of how we determine whether to use the night time or day time range of an NDB. Is it based on UTC or local. Furthermore do we need to calculate BOD and EOD to find what defies the period of daylight.
Lastly, is it our arrival or departure time that dictates if we use night ranges.
Thanks
Hi Will.
“Night Effect” is the reason for reduced range of a NDB at night time. From CASA’s website, a non directional beacon handbook can be down loaded. It states that the night effect is most pronounced with an hour of sunset or sunrise. So this means the range does not instantly drop at sunset, but over a period of time.
The definition of HN as found in the ERSA, is defined as being from sunset to sunrise so it’s local time. We don’t need to calculate first or last light, but we need to be aware of the reduced range and when we could anticipate receiving[map type=HYBRID zoom=2][/map] the signal for guidance..
Cheers W
The first light or last light graphs in the AIP are based on local time always. You must convert them to UTC or Standard Time. LMT is used only to extract the answer from the graph. LMT is of no practical use unless it is converted to UTC or Standard Time. Which one to use will have to be given in the question.
If you are not night rated, last light would be a consideration for your arrival. First light would be considered for your departure.
If you are asked for the 'hours of daylight' available, you would need to subtract first light from last light after converting them to UTC or Standard time.
