Destination weather for departure.

[OhNoCB]

Hope someone might be able to help with something I should know but have let slip from my mind.

Scenario is we are at airfield Y departing to airfield Z which has CATI ILS with 550m minimum and IRVRs. Will be an IFR flight.

Ops manual says (in accordnace with EU OPS I think) that weather at the destination must be equal to or above minima for a period of 1 hour before to 1 hour after ETA.

The TAF reads this:

171501Z 1715/1812 24006KT 0300 FG BKN000 PROB40 1715/1721 2500 -RADZ BR SCT003 BKN007 [...]

I can't recall how we deal with PROB30/40s and TEMPOs for planning. Could we go in the above case assuming an ETA of 1800? What if it was PROB30? What if it was TEMPO?

What if it it was changed slightly to say:

171501Z 1715/1812 24006KT 2500 -RADZ BR SCT003 BKN007 PROB40 1715/1721 0300 FG BKN000 [...]

Now can we go? What if it was PROB30? What if it was TEMPO?

I appreciate that a way around this is to have 2 destination alternates, but the question remains!

I appreciate any input guys!

[CaptainProp]

http://www.caa.gov.om/admin/upload/CAR%20OPS%201%20rev%202.pdf

Page 324 gives you all the info you need.

CP

[OhNoCB]

Have never seen that table before, thank you very much. Just getting my head round it now.

Would you agree that in both the examples I gave then it would be a no go?

Example 1 being a prob40 improvement (should be disregarded)
Example 2 being a prob40 deterioration (should be applied)

If however it was a tempo;

Example 1 being a tempo improvement (should be disregarded)
Example 2 being a tempo deterioration (may be disregarded)

you could go in example 2?

Just want to check I'm seeing things clearly!

[Klimax]

Not sure for your ops.
But probably it may also be relating to whether you are looking at showery (SH XX) type of conditions or not - when considering tempo WX. If its tempo SH then maybe it can be disregarded as opposed to tempo e.g. RA of NONE showery type eg. FG RA etc..

Just a quick add to the consideration.

[zakka]

you may not disregard a tempo deterioration. only if it is a "prob tempo"

[zakka]

Furthermore any precipation doesn't have any effects on planning. In case of an ILS at destination only vis/rvr matters