takata;
I think I basically agree with what you wrote. I just wasn't aware of it and thanks for patiently clarifying this point. However, I'm left with a few grey areas which may be relevant for what the pilots of AF447 saw.
The text you copied from the Air Caraibes memo appears on page 5 in the context of the protection named "CAS MONITORING" which in the BEA reports is the initiating event at 2:10:05 of the whole 2:10 sequence and results in the PROBE PITOT fault message after closing the one-minute correlation window.
Page 7 of the ACA memo shows pictures of the PFD speed scale in Normal and Alternate law in the context of an ADR DISAGREE message with Vsw in the Alternate Law 2 case.
While it may be unimportant whether or not a calculated Vsw is indicated on the speed scale when IAS has dropped to 60 kt or less, the intriguing question for me is whether it would be shown in the intermediate period when one or more of the indicated speeds had become valid again. EDIT:: Why should Vsw not be shown along the speed scale showing a 'valid' speed, first on PFD1, later on ISIS, and at an unknown time on PFD2?
Last edited by HazelNuts39; 14th Jul 2011 at 22:48.
Reason: EDIT