Anyone wishing to fly to Wilkes (ice) Runway (YWKS) on the Plateau, some 70 NM inland from the Casey Research Station, Australian Antarctic Territory, has to obtain CASA’s approval. Such approval would, among several other conditions and requirements, mandate carrying a GPS unit capable to provide guidance during non-precision approaches while receiving both L1 (civilian) and L2 (military) signals. In practice, two separate GPS units are carried and, during the only published instrument approach to that runway (RNAV/GNSS RWY 09T), are constantly monitored for “positional disagreement”.
And such “disagreements” do sometimes happen – “unpredictably” and for reasons that are not presently well understood. It appears, though, that the two GPS carrier frequencies are “never” affected simultaneously to the same degree. Thus, any “positional disagreement” calls for circling rather than straight-in minima to be used (i.e. doubling both MDA and minimum visibility for a Category C airplane).
What aviation GPS receives L2?
Military specs only, TTBOMK
RE: YouTube video in my post #27
Does anyone still remember any of Midnight Oil gigs?
Does anyone still remember any of Midnight Oil gigs?
Of course. But he was a much better singer than politician…
Synthetic vision – what options and what happens when database expires?
Potentially I am looking at a GTN750, or maybe something else in the form of two boxes one of which would be an MFD (EX600?).
What would concern me is if the database expiry kills the display. That is what happens with Jeppesen terminal charts presented on a panel mounted product. The display is inhibited 60 days (or so) after database expiry. (Same on the desktop Jeppview, but you can set the date back on a PC; you can’t do that on a panel mount product). With terminal charts one can construct an argument in favour of this (a poor one IMHO because most charts don’t change for ages and it is easy to verify validity by looking at the AIP update dates) but with SV it gets less good because most obstacles are just terrain and that doesn’t change over millions of years.
I didn’t think the GTN750 supported synthetic vision.
The terrain and basemap databases on the GTN have no expiry date, so they will stay current. The GTN650 manual says that obstacle databases have a 56 day expiry cycle, but are still displayed after expiry.
Peter, the Synthetic vision on a G1000 is driven by the terrain database. It does not expire as it is only updated irregularly ie once a year or so. The Obstacle database is also important. I will look into what happens with that.
I already have what Garmin call “certified TAWS”. That is just the same thing, maybe with some aircraft performance specific tweaks, which you get in the old G496. The non-certified TAWS doesn’t give you voice warnings, so is useless – like car satnav without voice guidance. But they still charge plenty for “certified TAWS”.
Is SV tied into that database? It could be – it could be the same data.
Also I wonder if there are any really good portable SV products. I have seen a few but none really worked properly – very slow and very “jaggy” displays. Modern GPS receivers deliver 5 samples per second. Yet, PC flight sims have had this cracked close to 20 years ago. Why is it so hard on an Ipad or some other tablet with an equivalent CPU speed? Admittedly the graphics coprocessor in an Ipad is crap compared to a high end PC one. The hi-res database for X-Plane for the whole world is about 30GB (my son once had this).
My Aspen has the original SV data. When you turn it on, it will show the database versions and require you to accept it. I do not plan to update it.
