The one calculation which I constantly find myself doing during the last 6 miles when establish on the ILS is "What should my rate of descent (RoD) be?"

Now I know that the glideslope gives that to me as a visual "..too high, too low, just right...." but somehow I always like to have secondary confirmation of these things especially when all I can see is wall to wall clouds outside the cockpit and I know that the ground is coming up to meet me in the not too distant future!

To have an indication of what the necessary RoD should be in order to land on the numbers and to correlate that to the aircraft's VSI would be a very comforting addition to SD's armory.

At the moment, I'm doing it in my head on the decent at a time when the workload is at its heaviest. Some how I really think that, since SD is doing this calculation constantly in the background; advises me at the start of the virtual ILS approach of the required RoD; a simple display inside the virtual ILS instrument followed by a quick flick of the eyes to the cockpit VSI would do the job in a matter of seconds.

So what do you think for all of us (V)FR fliers?




Biggles -- EGKB

SkyDemon does flash up an alert when you intercept the GPS-based glideslope telling you what your rate of descent should be based on your current lateral speed, but I do not want a permanent instrument showing this on display as people may rely on it more than we are comfortable with. SkyDemon is supposed to be for VFR flying.

I acknowledged in my 1st message that SD does indeed give the RoD at the start of the pseudo ILS phase. However, if you miss it then there is no way of recalling it -- Pity.

I understand your point that this is a VFR application, but the pseudo ILS representation that you offer intimates other options for the VFR flyer and all that a RoD digital display would be doing is to interpret the GS line on this display in another way, so in essence you are already supporting the idea but as a graphical display (GS) only.

OK, I'll just go on doing it as I always have -- It's amazing how adept you can become at using a Pooleys Computer one-handed!

Biggles -- EGKB

Biggles-EGKB, iPlease permit me to iAgree with you once more.

Multiple airspeed by 5 and that gives me my RoD for a 3.5 deg glide slope - yes I remember that from my PPL training days. That's great if the aircraft is properly established on final and the aircraft remains in this ideal world but if SD's GS indicates that I am too high at 2nm with a ground speed of 80kts multiplying by 5 has a tendency to land me on the upwind numbers on a medium length runway (leaving me heavy on the brakes and no rubber on the tyres) and in the hedge on a short runway (leaving the airfield with no hedge and me a very expensive lawn mower)

Now with a constant display graphically (which SD already gives via the GS) and the possibility of displaying digitally the actual RoD required to achieve the landing point (just an idea at the moment), serves to improve my chances of landing on the downwind numbers which the nice people in the tower suggested might be a good idea next time I give it a go!

Also, thinking back to my PPL training days I never could quite understand the "rule of thumb" of multiplying the airspeed by 5 (it doesn't work) as you quite rightly state it is your ground speed that's important in working out the RoD not your airspeed and what is the one thing that the standard 6 pack instrument cockpit display doesn't give you that a GPS device like SD does -- yes, you've got it GROUNDSPEED.

Now where did I put my Pooleys?



Biggles -- EGKB

Ummm, I think I'd rather you just looked out of the window to be honest...

I realise that SD is a VFR flight software application but "information is everything when flying, redundancy is reasuring and I'm looking out the window as you suggest and and and ......."

White fluffy things, 100% coverage -- currently @ 1200ft QFE with DH of 600ft and required RoD uncertain but cockpit GS indicates I'm high which is confirmed by SD's GS display; I'll guess at about 450-600ft/min (give or take a few hedges).

......and and and, let's look on the bright side, the guys in the tower might quite like another hedge cutting

Biggles -- EGKB

More relevant information, is a prerequisite to better decisions. ROD and AC position constantly vary in flight. Now would it be better to avail such info to the pilot or do we feel that it would be unsafe to do so? I certainly would have appreciated even approximate info when both my suction pump and air speed indicator packed up on take off. Something is better than nothing I'd say.

Very Newbytheway

DurhamTeaseAirport

On my iPad 3 the gps derived height is around 200' below the QFE, and the SD glideslope is on the bottom of the scale when I'm actually on slope. So I'm not about to rely on a £600 iPad to keep me alive any time soon, and even as backup I think I'd have to have a WAAS gps addon before I even went to 600'