Meteorological question
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Meteorological question
Just read the latest general forcast for ML and was wondering what "SAM" is. I notice it pops up every now and again and can't find it in any of my books.
THERE IS A POSSIBILITY OF VISIBILITY REDUCTIONS AND LOW CLOUD BEING MORE SERIOUS THAN FORECAST, ESPECIALLY IN THE VICINITY OF THE FRONTAL PASSAGE AND SAM CRITERIA MAY BE MET. CONDITIONS DURING THE 14-24Z PERIOD SHOULD BE GOOD WITH DRY NORTHERLY FLOW. THE TIMING OF THE FRONTAL PASSAGE COULD BE OUT BY AN HOUR OR TWO AS THIS FEATURE IS SOMEWHAT DIFFUSE IN THE MODEL REPRESENTATIONS. WIND GUSTS IN EXCESS OF 25 KNOTS ARE POSSIBLE FROM EARLY FRIDAY MORNING UNTIL EARLY EVENING.
It used to be refered to as SLAM, special low alternate minima, and for some reason the 'low' bit has been removed.
6.2 Special Alternate Weather Minima
6.2.1 Special alternate weather minima are available for specified approaches
at some aerodromes for use by aircraft with dual ILS/
VOR approach capability; ie, with duplicated LOC, G/P, marker
and VOR receivers. The requirement for duplicated marker receivers
may be satisfied by one marker receiver and DME. (The
assumption is that such aircraft will also have two ADF systems,
when an NDB or Locator is used for the ILS).
6.2.2 Special alternate weather minima are identified on applicable instrument
approach charts by a double asterisk adjacent to the ALTERNATE
title and a note detailing the special minima. These special
alternate minima will not be available (minima will revert to the
standard alternate minima) during periods when:
a. local METAR/SPECI or forecasting services are not available;
or
b. an aerodrome control service is not provided.
The non-availability of MET or ATS services will be notified by
NOTAM.
6.2.3 Where:
a. there is a protracted unserviceability (ie, more than seven
days) of any one VHF approach aid, or
b. facilities required for the conduct of a VHF-based instrument
approach and landing are unserviceable or not available,
Airservices Australia will, if necessary, advise the non-availability
of, or any revision to, special alternate minima by NOTAM.
6.2 Special Alternate Weather Minima
6.2.1 Special alternate weather minima are available for specified approaches
at some aerodromes for use by aircraft with dual ILS/
VOR approach capability; ie, with duplicated LOC, G/P, marker
and VOR receivers. The requirement for duplicated marker receivers
may be satisfied by one marker receiver and DME. (The
assumption is that such aircraft will also have two ADF systems,
when an NDB or Locator is used for the ILS).
6.2.2 Special alternate weather minima are identified on applicable instrument
approach charts by a double asterisk adjacent to the ALTERNATE
title and a note detailing the special minima. These special
alternate minima will not be available (minima will revert to the
standard alternate minima) during periods when:
a. local METAR/SPECI or forecasting services are not available;
or
b. an aerodrome control service is not provided.
The non-availability of MET or ATS services will be notified by
NOTAM.
6.2.3 Where:
a. there is a protracted unserviceability (ie, more than seven
days) of any one VHF approach aid, or
b. facilities required for the conduct of a VHF-based instrument
approach and landing are unserviceable or not available,
Airservices Australia will, if necessary, advise the non-availability
of, or any revision to, special alternate minima by NOTAM.
