Today I sat in the cockpit of an almost new Citation 4 which has AoA indications on the Collins Proline kit…
Oh yes, I forgot about the one on the screen. Out AoA derived Vref is indicated on the speed tape as a little triangle. That’s a good backup for the Vref computed from the (estimated) landing mass which is also displayed on the speed tape. I’m pretty sure however that the AoA on the Proline screen that you saw is not computed, but also driven by the AoA vane, because in order to be able to compute it, you need the exact mass of the aeroplane.
the AoA on the Proline screen that you saw is not computed, but also driven by the AoA vane, because in order to be able to compute it, you need the exact mass of the aeroplane.
For the Vref it has to know the passenger number and their average weight, etc. For the AoA, no idea and I am sure you are right.
I am about to buy the Griffin kit. Can anybody think of a reason against it?
exactly 1,995 reasons (+ shipping) against it 
Ha! Beat me to it… :-)
I should add that the purpose would be to more accurately reach the aircraft operating ceiling.
The Vref shown on Proline 21 screens in the Citation is derived from the AoA sensor and is correct at all weights. It does not require you to put in any weights, and it also sorts itself out whatever the flap position.
I use it in training for things like the no hydraulics (flapless) landing as it is better than looking up the revised Vref from the Abnormal Checklist. It is also a superb sense check for computed speeds when setting the speed bugs on the AS tape. If you send up with a bugged speed which is far off the AoA “doughnut” on the ASI tape you probably have finger trouble!
I have met some pilots who use the little traffic light display on top of the glare shield every approach but I never look at it.
In the CJ if you are anywhere the doughnut when climbing with both engines at any height you are going far too slow!
The Vref shown on Proline 21 screens in the Citation is derived from the AoA sensor and is correct at all weights. It does not require you to put in any weights, and it also sorts itself out whatever the flap position.
That would mean it works only during flight – correct?
Peter, I am surprised you need an AOA sensor to accurately reach the operating ceiling. Can you please explain some more your rationale?
How would you reach the operating ceiling?
