Originally Posted by
FGD135
Yes, I know that the TAF status for any one particular place doesn't change frequently, but over the course of a year, you may have one or two dozen places where the TAF status changes. That would then be one or two dozen lots of amendments to IAL charts that didn't need to happen.
How often does an aerodrome change from TAF to No-TAF? If we're talking about superfluous amendments to the plates, then let's take a look at tomorrows Jeppesen revision cycle, 20 Dec 13. Remember that this is not even a revision date at all for the AIP DAP.
Adelaide One SID amended due to "initial climb text".
Albury DME arrivals (all of them) amended due to Cat C Minimums.
Albury Aerodrome chart amended due to changed alternate minima.
All the other Albury approaches amended due to changed circling minima.
Amberley aerodrome chart amended due to "note added".
Ballina aerodrome chart amended due to alternate minimums.
Coondewanna aerodrome chart amended due to "note added"
Hughenden (all plates) amended due to AWIB added.
Leinster aerodrome chart amended due to runway length.
Lismore RNAV 33 amended due to mandatory altitudes.
Mackay aerodrome chart amended due to parking bays.
Mansfield RNAV 115° amended due to MSA
Melbourne aerodrome chart amended due to Note Added
Moorabbin NDB-A amended due to missed approach training note
Mildura(all plates) amended due to AWIS removed, AWIB added.
Mt Gambier aerodrome chart amended due to takeoff minima, lighting
Naracoorte GPS Arrival amended due to MSA and profile depiction
Naracoorte RNAV and NDB amended due to MSA
Osborne Mine aerodrome chart amended due to RWY 30 lighting
Osborne Mine RNAV 30 amended due to PAPI added
Sunshine Coast aerodrome chart amended due to RNAV-X alternate minima
Sydney aerodrome chart amended due to parking bays renumbered
Sydney ILS-Z 16R CAT II amended due to RA added
Sydney ILS-Z PRM 16R CAT II amended due to RA added
Sydney ILS-Z 34L CAT II amended due to RA added
Sydney ILS-Z PRM 34L CAT II amended due to RA added
Sydney VOR 16R amended due to straight-in minima deleted, altitude table
Tennant Creek all plates amended due to AWIS added.
I'd say the occasional once or twice a year an airport changes landing minima to be pretty minor in the grand scheme of things.
Originally Posted by
FGD135
Alternative logic, that still keeps things as simple as possible, would be to have a published figure that assumes you have a TAF QNH. Then, if necessary, you:
1. Add 50' if using area QNH;
2. Reduce it by 100' if using an actual aerodrome QNH.
Perhaps I missed the sarcasm if there was any, but that is exactly how the current charts work. The published minima assumes you have a TAF QNH. If you are using Area QNH, then you do indeed raise the published minima by 50 feet. If you do have an actual aerodrome QNH, then you do indeed lower the published minima by 100 feet. That's what the shaded background indicates!