I have had the static being blocked once (not due to icing), which was a peculiar experience, but nothing the GPS didn’t solve (not a perfect solution, but it got me down with no functioning IAS). I wouldn’t say unheated pitot is dangerous in VFR, it is very much unnecessary. I see that heated pitot is part of the required equipment for NVFR now, after SERA (or was it part NCO?), but I don’t understand why. Icing and darkness is very unrelated phenomenon.
Icing and darkness is very unrelated phenomenon.
Probably because it is so easy to be flying in VMC at night at -5C and quickly pop into a little cloud (which on a proper night you could not see) and ice up your pitot.
Of course night flight, on a proper night, is 100% instrument flight, but that’s another debate 
The big question is how do you safely operate using AoA? Having an indication is helpful, but how do you incorporate it into your operation?
Obviously the military are streets ahead as they do pretty much all their flying when not S&L on units of AOA, especially the USN, but are you going to start flying AOA on approach? In the climb? What relevance does it have in the cruise?
The Lear has an AoA gauge in the far left/right corner of the cockpit for each seat. It is graduated from 0.0 to 1.0, with a red band 0.8-1.0 where the stall warning occurs at 0.8 and the wing stalls apparently around 0.9-1.0, but there is no training or written guidance in how to use it in normal ops, and only cursory training in use in unreliable airspeed. I have memorised my crib of alpha values for key flight phases from observation, but it’s not in direct seat and not easy to use at any stage.
I have seen the various graphic indicators available for STC type installations – I guess you would fit them on the glareshield/next to the PFD or similar, but how is the green range and so on calibrated? I guess in Peter’s case of wanting to fly the optimum AOA for max ceiling climbs, one would fly the book airspeed at the book weight and note the AOA and then use the same AOA at lower weights?
I wouldn’t say unheated pitot is dangerous in VFR, it is very much unnecessary
Neither of my aircraft have a headed pitot, and I’ve never needed it. Obviously northern Europe is a particular GA market, with its own particular needs. However, I don’t see ice protection in relation to AoA sensors as being central to most potential customers.
I guess in Peter’s case of wanting to fly the optimum AOA for max ceiling climbs, one would fly the book airspeed at the book weight and note the AOA and then use the same AOA at lower weights?
The problem is/was that I could not be sure whether the current light GA AOA products even work at altitude. IOW, does the principle still apply? They don’t measure AOA directly like e.g. jets do (with a rotating vane which of course is heated); they get it via the proxy of a differential pressure in two holes.
When I put this to the firms they avoided the question and when I repeated it they stopped answering So I decided to not waste my time – the message in such a situation is obvious. It may work but who knows?
Aspen AOA Upgrade
I just posted this over on the MMOPA site for fellow PA46 owners. Thought it would be of interest here.
E
Having installed the Aspen AOA upgrade, l am a self confessed believer in its usefulness.
Firstly the installation details and calibration:-
Since this is a software upgrade only, there is no physical installation, merely upgrading the Aspen PFD firmware, and then unlocking the AOA feature.
As mentioned by others, some precise base data points are required to be input prior to the calibration flight, relating to speeds and weight.
After that the calibration flight is made at various speeds and configurations.
I flew the calibration flight with my instructor, after which we proceeded to test it.
My initial impression after 5 flights, is that it works as advertised. It correctly predicts and tracks the stall both clean and full flap configuration.
Where it adds a real value for my missions is providing the confidence for much more precise approach speeds, which in my case is especially useful operating out of short fields.
Whilst experimenting, l was able to reliably reduce my approach speed by 5-10 Kts whilst still maintaining a good margin of lift reserve. Normally, l would approach shortfield over the threshold at around 85-90 Kts. Using the AOA as to primary indicator, it became evident that 80 Kts, two people up, with half fuel weight was still a very controllable and comfortable approach speed, resulting in a much smoother touch down and shorter roll.
Going by the display, the approach AOA indicator was only just into the yellow lift reserve area at 80 Kts, and it was only at 75kts that it moved towards the middle area of the lift reserve section. Obviously this will vary with weight etc, but that is the big advantage. By pegging the AOA instead of the ASI, the speed will resolve itself.
It still feels strange not reacting to the ASI, but that will change with time and confidence, l am sure.
So far, l have been limiting the testing to large runways until l build up my confidence with the AOA reading to rely on it completely, but based on what l have seen so far, l will switch to using it as my primary reference on the final approach to landing. Very nice upgrade.
Great feedback!
Does it have flap position input?
Have you tested the accuracy at both low levels and say FL200? That was the Q which Alpha Systems repeatedly avoided answering. Nearly everybody thinks about this in terms of low level envelope protection but the other application is optimisation of the pitch angle for the operating ceiling, in difficult VMC-on-top conditions.
The Aspen does not have a flap position input, instead it has a dual pointer representation, the lower pointer is full flap.
Apparently, the latest Alpha Syatems version for the PA46 does now have a physical flap position input, although l think it is binary, and only indicates full flap.
The other advantage of the Aspen implementation is that it provides a linear display, instead of the more traditional traffic light donut display , so you can see the trend on the Aspen.
I did the calibration at FL180, and then checked it at that level as well as 3,000 ft, and on actual approaches. It was bang on in each case.
Considering this is derived technology, it is actually quite impressive.
E
PS. This image is not from my installation. I only have one PFD.
First of all, this is indeed impressive.
But may I ask – why did you not trust the POH, and fly the (weight corrected) approch speeds in the manual?
Cobalt wrote:
why did you not trust the POH, and fly the (weight corrected) approch speeds in the manual?
One thing to always keep in mind is that your air speed indicator is considerd to be within tolerance with an error from -5 to +5 Kts. Which can make quite a big difference.
