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Skydemon (merged thread)

I have Sky Demon in front of me and that piece of airspace shows as starting at 4,500ft. Were you using an external GPS or the iPad internal GPS? What altitude were you at?

Interested as I am a Sky Demon user keen not to be making any CAS busts...

EGBP, United Kingdom

4000-4500ft.

But regardless of what height SD shows inside that "kink" (it appears to show it correctly as 4500ft) how can that thick line be correct?

Unless there has been a change in the airspace since the current southern UK chart came out last year.

Administrator
Shoreham EGKA, United Kingdom

I see what your saying. SkyDemon has joined two or three quite separate boundaries and presented them as one, and therefore with an altitude level that is incorrect.

I love SkyDemon and use it as my primary planning tool. However there are multiple options for showing and hiding different classes of airspace, and levels above and below you, so as a general rule I always transfer my route to my CAA chart, and I always note down on a bit of paper what the lower and upper limits of CAS are for each leg.

For me this comes down to not relying on one tool for everything. It's why I also cross refernce NOTAM's against the AIS site as well.

It is a 'feature' of the de-clutter and how the software is configured by the user - I think. I have a route plotted now running from LGW out to BEXIL just to simulate a route through that piece of airspace. If I set my level to 3,500ft I only see the kink, not the southerly boundary of the higher piece of the TMA. If you are airborne, going from memory, it will draw you a thick yellow line and flash a warning for the airspace you are about to enter/infringe along with a frequency.

I would guess this is a nuance/nuisance (depending on interpretation) in that the thick line you were seeing (and how you see it will depend on the chart style you have selected for presentation) for the piece of airspace it thought you would next enter. I can see though how it could become confusing where there are layers of airspace as there are at that point. I am on their beta tester list so I can try and feedback what you saw.

EGBP, United Kingdom

Unless there has been a change in the airspace since the current southern UK chart came out last year.

I dont know if this is true for that particular bit of airspace, but this is where things get murky. SD updates it's charts very frequently (weekly, almost). The UK NATS VFR charts are updated every year (I think). And in the meantime NATS AIS send ad-hoc VRF chart amedments via email over what seems like a whole day. I generally take note of things likely to affect me in my local area, but I struggle to keep up with all the updates and at a given point in time find it hard to know exactly what up to date and whats out of date. Given a conflicting choice I guess I go for what seems to be the safest or lowest of the options.

PiperArcher I think has it right. Although assuming you were heading towards Gatwick and likely to infringe, given the GPS height you were at, the software has drawn you a line of where you don't want to be going and presented you with the bit of clear airspace you can be in, which to me make sense at least, or am I missing something fundamental here?

EGBP, United Kingdom

However... this doesn't answer why you didn't see the thick, presumably yellow line until you were already turning away from a bust. Most likely reason would be a GPS issue I would have thought. On some of the older iPad's I think the software is perhaps a bit demanding for the hardware. I run it on an iPad3 (mainly now for planning, although we did a long trip last year with the iPad on the right yoke) and on iPad Mini. On the internal GPS I have seen more dropouts than are ideal, so the mini which fits comfortably on the yoke without obscuring anything is using an external GPS which seems to work much better.

EGBP, United Kingdom

If the thick line shown by SD was supposed to show the extent of airspace which could be flown into at the current altitude that would be quite clever but would still not make sense, because the 4500ft CAS base has no boundary as shown.

We were well away from any airspace when we were looking at that particular issue.

GPS reception was fine - also as per the GNS530. Anyway, there is no way GPS reception could explain the way that "kink" was depicted.

Administrator
Shoreham EGKA, United Kingdom

I remember a discussion on PPRuNe or Flyer a while back where we found that the airspace depiction on the CAA chart was dead wrong, and had been wrong for a while (multiple years). This was at some place where two or three different TMAs came together, somewhere NW of London.

Apparently the CAA chart maker had cut a few corners (*) to make things more readable, while SD simply took the raw AIP data and displayed that.

(*) Actually he added a few bits of CAS so that the CAS boundaries would be aligned and map presentation would be easier. But the net effect was that the CAA chart showed CAS where there was no CAS. The consequences were minor - this affected an area that was just a few nm across, and only at one specific altitude band which was, from memory, about 1000' thick.

I would not be surprised if the exact same thing would happen here. Has anyone looked in a competing product, for example Air Nav Pro, or a Garmin product, to see what the AIP-derived airspace depiction looks like over there?

Yes, the GPS won't cause the kink, however I suspect a partial dropout could have the software not certain of position/speed/direction of travel and therefore not predict where you were heading correctly and so not show the warning until you were already turning away. To show you what the software thinks of the airspace boundaries here are some images I have just taken on a chart updated today. Each clip shows as if I was planning the selected route at 3, 4 & 5000ft and probably explains what you saw. There are also options in the setup menu where you can choose either time/distance before a warning will be displayed and also what to warn for.

EGBP, United Kingdom
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