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ATIS v AWIS
awol
Topic Author
awol created the topic: ATIS v AWIS
Hi Bob/Richard/others...
Found the following on the net...
I remember the 2 questions i got wrong, both related to the MDA. In Bob Taits book which i used and highly recommend, he had a couple of trick questions with the QNH. If you have the QNH for a location and the charts box is shaded, you can subtract 100 feet of the MDA. BUT in Bobs book he said that if the question didnt mention that you had the QNH assume the normal MDA, which i did and got them wrong. I should have subtracted the 100 feet as the plates had AWIS available on them.
BUT thats casa exams for you.
The following is one of Bobs replies from about 14 months ago:
When it comes to subtracting 100 feet from the MDA or Alternate Minimum, the QNH must be from an 'approved source'. ATIS is considered to be an approved source because if the QNH changes significantly, a new ATIS is prepared. AWIS on the other hand, is broadcast on VHF at some aerodromes, but it is available only via phone at others. CASA's interpretation is that if you get the ATIS by VHF - that's OK. But you can't be sure before you depart that the mobile phone service will be available. So QNH from AWIS by mobile phone is not considered to be an approved source.
So my question,
In case a question like this shows up on my IREX exam next week, When an aerodrome has AWIS can you or can't you subtract 100' from the DA/MDA if the box is shaded???
If an aerodrome has AWIS or ATIS you certainly can subtract 100 feet providing the box is shaded. When I said to use the published MDA unless the examiner tells you that the actual QNH is available, I had in mind the students who assume that whenever the box is shaded you can automatically subtract 100 feet without considering AWIS or ATIS.
If the DAP or ERSA say that the aerodrome has AWIS or ATIS, you are effectively being told that the actual QNH is available.
However, obtaining AWIS from a mobile phone is not considered an approved source.
Further to the above discussion, here is CASA's reply to a question I asked on the use of mobile phones for operational purposes.
Hi Bob,
You are correct.
IFR aircraft must have appropriate VHF (and HF as appropriate) radio equipment serviceable prior to flight. CASA expects that this equipment would be used in flight to obtain any flight information required. A telephone may only (with a few exceptions, satellite phones for example) be used as a non-normal means of obtaining information or alerting air services as the case may be, it is not approved for general use in an aircraft and should not be used to obtain the AWIS 15 minutes before the approach.
A decision to use the lower alternate minima is therefore based on an aircraft's ability to use this mandatory radio equipment, not a phone.
Phone numbers are listed in ERSA for AWS simply because the information is available via this medium and may provide pilots with further or current data when flight planning.
Hope this answers you question.
