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Whenweather conditions at the destination are forecast to be as specified
as above, but are expected to improve at a specific time, provision for an
alternate aerodromeneed not bemade if sufficient fuel is carried to allow the
aircraft to holduntil that specified time plus 30minutes (AIPENR 1.1).
Whenweather conditions at thedestination are forecast tobe above the values
specified above, but additionally, intermittent or temporarydeteriorations in the
weather below those values are forecast, provisionof an alternateneednot be
made if sufficient additional fuel is carried to allow the aircraft tohold for:
• 30minutes for intermittent deterioration (INTER); and
• 60minutes for temporary deterioration (TEMPO) (AIPENR1.1).
When thunderstorms or their associated severe turbulenceor their probability
is forecast at the destination, sufficient additional fuel must be carried to
permit the aircraft to proceed to a suitable alternateor to hold for:
• 30minuteswhen the forecast is endorsed INTER; or
• 60minuteswhen the forecast is endorsed TEMPO (AIPENR 1.1).
INTER andTEMPOholding fuel requirements are not cumulative therefore,
when a forecast has a number of INTER or TEMPO deteriorations, holding
fuel is required only for themost limiting requirement (AIPENR1.1).
When TAFs include a FM or aBECMG causing anoperational requirement
to either become effective or be removed, the timing for the change in
operational requirement is as follows:
• when theweather during the FM or BECMG is forecast to create an
operational requirement, that operational requirementwill become
effective 30minutes before the onset of the FM time, or 30minutes
before the start of theBECMG period.
• when theweather during the FM or BECMG is forecast to remove an
operational requirement, that operational requirementwill remaineffective
until 30minutes after the FM time, or 30minutes after theend of the
BECMG period.
The additional fuel required by the above paragraphsmust be carriedwhen
theETA of the aircraft at its destination or alternate fallswithin the period
of 30minutes before the forecast commencement time to 30minutes after
the expected time of cessation of these deteriorations (AIPENR 1.1). If the
holding time requiredbecauseof INTERor TEMPOor theprobability of INTER
or TEMPO requirements (as described above) extends past 30minutes after
the forecast cessation of these deteriorations, the aircraft needonly carry
sufficient fuel to hold until 30minutes after the forecast cessation time.
alternatedue toweather
2 – preparat i on