Doc and all,
The issue is not whether we can use a Metar to reduce the MDA by the 100ft: that is not allowed. My enquiry is whether we can use a Metar at all.
A typical scenario is this: 30 minutes from the destination we get the latest Metar from Flightwatch (which may be up to 30 minutes old). We then set this on the altimeters and do our instrument approach (not reducing the MDA).
Under the new rules, is this legal?
And if so, how old can the Metar be before we can't use it?
Is this why CASA created the rule (so that any old Metar can't be used?)? If so, and given that a Metar (by definition coming from a BOM observer) would most probably be more accurate than the airfield TAF, why can't we use a Metar if it was, say, up to 2 hours old? After all, the TAF only has 3 hourly QNHs on it.
