Yanr, let's get this straight. Two key points will be enough.
Originally Posted by
yanrair
First I must object to you repeatedly using my maths errors in a previous post, which I have since corrected, to suggest that the use of GS in UAS is a not worthy of consideration.
A) Stop twisting.
1) I had not used your math errors before, ever. Even in the post you have in mind, and that was only once, I used the CORRECTED math, which is the one that would have put the crew into a stall at Vref-40 kt.
2) I did not suggest GS was not worthy of consideration in UAS. Au contraire, post #47 "This thread inspires me to include GS in that scan the next time."
B) Heed your own advice
Tackle the ball - not the man.
...you do memorise the .... which isn't too hard because I can do it. ...
...On a point here, have you ever actually done any of this for real? It sounds to me as if you haven't. ...
... you can reject the entire argument on the basis of an error in one part ....
... very simple table which I know you don't like ....
... Off to see my therapist now...
--- now, if we can play neat ---
About the GS uses i.a.w. present OEM guidance:
you decided to quote
BOEING QRH 737-400 Line 4. CROSSCHECK IRS AND FMC GS AND WINDS TO DETERMINE AIRSPEED ACCURACY...................
It does not say "to determine airspeed
accurately" as in:
and then fly the GS, which is what you seem to propose through the previous posts.
The full version from my copy (click here): says
below the dashed line
4. Cross check the IRS and FMC ground speed and winds to determine airspeed accuracy if indicated airspeed is questionable.
-> To me that reads: try with GS to figure out if any of the ASI can be trusted and the scale of the error at hand. No mention of flying anything through GS.
The Airbus instructions are somewhat different, (
click here for the basic scheme).
- The last element in FCTM wording: "Flight using pitch/thrust references or the BackUp Speed Scale (BUSS, below FL 250), if the troubleshooting has not enabled to isolate the faulty ADR(s)." has almost a full page of explanations. No GPS reference at all.
- The "Troubleshooting and Isolation" does not mention GPS or GS at all, again. Though in cruise I personally would. Looking at the CoFP and comparing the printed GS against the present display readout, keeping in mind the difference between the two observed previously.
- The "Flight path stabilization" is where they acknowledge use for GPS
altitude. As a suggestion, after what is already 20 lines of text in that paragraph on how to fly stabilized.
The GPS altitude can be used to confirm that the aircraft is maintaining level flight.
Originally Posted by yanrair
...how are we going to fly our plane in wide range of situations using the GS as a reference as given to us in the QRH.
There no reference to do that in the 737 QRH. There is whatsoever no reference to GPS GS in any of the UAS / ADR / Disagree procedures on A320/A330, FCOM, QRH, FCTM and memory items included.
I have no issues with your graph, which is correct and valid. The observation was: For the sorry AF447 crew who that night did not have the ken to maintain the cruise pitch and not touch the thrust-levers, memorizing certain datapoints of it (50 kt/ 10k ft) would not have helped.
Later, when fully stalled and perplexed due to the confusing indications both active and missing, the meaning of 60 kt-ish GS could have lit a spark that could have saved them all, definitely yes - but even for that the TAS table is absolutely irrelevant.
I do opine, OTOH, that the claim of flying accurate speed under UAS using a GS readout is bogus. The present procedures - which do not include any GS at all - give good enough result within 10 knots already as they are. Attempt to finetune that with GS would most likely unsettle the whole process, given the dynamic nature of the atmosphere itself. Very different outside compared to the SIM one.
Pass my greetings.