BurnieM

Tried to find an old paper (with no luck) that suggested that small sky view could still produce a good fix with low horizontal errors. Cannot remember what they said about vertical errors. With the current 31 operational GPS satellites I believe you can get low error positions with less than 50% skyview. Certainly observation in commercial jets thru a very small window suggests you can get good postions with signifcantly less than this. Yes, a good spread of satellites is required but with 31 operational this is only rarely not available. I have never opened a SkyEcho but some reported issues surprise me. Its odd when good quality GPS receiver/antennas can be purchased for less than US$15. Tried to find the GPS specs but they do not even quote the number of channels. Pulled out an old car GPS (Garmin Nuvi 50) from 2012 with 12 channel receiver. This is in my front yard with 30 degree shading to the north, 20 degree shading to the east and west and -20 degree to the south (yes I am on a hill). By shading I mean from horizon to say 20 above horizon is not visible to the receiver. At my home in northern suburbs of Sydney I am receiving 10 satellites and it is indicating a horizontal error of 4m. The only time I have seen large errors in the last 10 years is when driving thru the Sydney CBD.

Generally you should see a horizontal error less than 10m and a vertical error less than 20m on a consumer grade GPS. Consumer chipsets typically calculate position once a second altho for slightly more chipsets that calculate position 5 times a second are available. I would consider a vertical error of 100m to be extreme and in most circumstances would expect moving map software to either ignore the position or display a large warning message. Depending on what you are trying to do you could display without message or do averaging. In critical use I would not do either but in aviation I would probably still display it with a very visible warning. Every consumer GPS I have seen calcuates its own potential error.

In a previous life I worked for a specialist GPS retailer (not aviation) and took Garmin hiking GPSs on 737/747 flights many times. Even thru their small windows with earlier model GPS chipsets (15+ years ago) I very rarely saw major errors. I find a 1500 ft error (even a vertical error) on a calculated position with a modern GPS chipset to be troubling.

Just confirming I have got this right; there was a 1500 ft vertical error in the GPS position sent from the Skyecho ? This appears to be nothing to do with potential errors between baro and GPS attitude and everything to do with poor satellite spread or number of received satellites and either; 1. the high potential error calculated not being passed to the moving map software or 2. the moving map software ignoring the potential error and displaying position without a warning. (apparently Skydemon does display an potential error but not promenently). The UAvionix response in the video is misleading to say the least .

Not saying 'electrically dependant' is not an issue to be remediated but is it actually a bigger risk than carbs/magnetos ? The 912IS requires battery power to start but not to run. The IS has two alternators with the first being 10?amps for engine (ecu/fuel pumps/spark). If this fails the ecu can switch everything automatically to the second 30?amp alternator (normally used for avionics/battery charging only). If the second alternator fails then the engine will stop. Reconnecting the start power will allow you to restart the engine but it is recommended to reduce the avionics load and land with 30 minutes. This seems like a pretty fair level of redundancy to me. You can also fit a third external 30amp alternator but this can only be used for avionics/main battery charging.

The Rotax 912ULS and 912IS of similar vintages are pretty similar in climb and cruise preformance. The IS is more fuel efficient in cruise. Is the 914 still an option ? Look at the 915 for a fair bit more in cost. The power requirement/backup issues of the IS seem well known and allowed for and the 912IS has been flying for 12 years. The both versions of the 912 seem ideally suited for either 600 or 760kg. Are you really looking at high attitudes ? A lot of these aircraft have limits of 13,000ft (ish) The Sling 2 is both an LSA at 600kg and a VLA at 700kg and was flown around the world in 2009 at 900kg each day for 40 days. It used a 912ULS. With this aircraft going to class G this will now (soon?) allow you to take 2 people with full tanks. If you want to fly both engines then Fly Illawarra have an Evektor Sportstar with a 912ULS and a Evektor Harmony with a 912IS.

With Group G looking to have similar maint requirements to GA perhaps group G owners will stay with Casa if they can self assess (and some VLAs ie Sling 2 may go back). Interesting timing on these 3 (PPL self assess, RAA group 4 and RPC controlled endorsement). I guess as long as more people can fly more places with more fuel its all good (if/when it actually happens).

Possibly VFR up to 10,000 only with Class 5 PPL (guessing from no night VFR) and controlled endorsement with RPC at about the same time to reduce arguments. Anybody have any more info. If CASA don’t stuff it up and make it too restrictive would this make RAA less attractive ?

The Travel John semes to be designed for exactly this situation; https://www.platinumhealthsupply.com.au/products/traveljohn