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malcolmfrost wrote:Just out of interest I checked the inertial drift on a one hour flight yesterday and it was 1.5nm....
That would fit with 10 nm crossing the Atlantic

I have two tablets. One runs SkyDemon and the other runs Airbox RunwayHD. The challenge would be if GPS was lost due to noise or jamming. You can buy jammers off the internet to disguise where you've taken your lorry or the BMW you just nicked.

Curiously I just found out my Asus Zenpad is supposed to pick up Glonass. So maybe things are better than I feared.
Whether we think that GNSS signals, or the technology behind them, are robust or not - they can fail.

There are a whole bunch of backups for when that happens - declaring lost on RT, VOR+/-DME, even ADF for the masochistic purists.

But one backup is, and should always be there - basic pilotage, comprising situational awareness, a paper chart (or even a chart on a tablet with a "GPS has failed" cross across it), a good old fashioned PLOG, and most times and places - looking out of the window at the ground.

Bluntly, but sincerely - anybody incapable of working out where they are and getting somewhere safe and sensible if most of the electronics go tits up (particularly flying VFR) should not be putting themselves in charge of an aircraft, any aircraft, until they've sorted their basic piloting skills out.

Doesn't have to be easy, efficient, or even enjoyable (although many of us do quite enjoy the challenge of flying VFR nav competently) - but it's a skillset we should all have.

Faffing about with exotic expensive technologies is absolutely no substitute for maintaining basic flying skills.

Sorry, bit of a rant there, had to get it off my chest.

T67M liked this
I agree, I have a paper chart and a printout of my SD produced Plog and keep cross referring from the ground to the tablet/phone and vice versa. However, when the technology exists to navigate accurately, then in the current restricted airspace we would be silly not to use it, but be prepared to call lost (either with D&D or a local ATC) much quicker than I suspect we do .
Personally I have to have a high level of confidence in the GPS system as I have to fly down to 500 feet altitude at 150 kts on an RNAV procedure! Whether I am competent enough to navigate accurately on teh NAT tracks with a chart if teh GPS fails, who knows, AFAIK it hasn't happened to ant CAT. Yet! :D
If your worried about GPS reliability.
1) it’s far far far more reliable than a map etc. 99.99% of the time you know exactly where you are. And quicker to use so you can spend more time looking out of the window.
2) get yourself an aviation GPS. A nice GPS/NAV/COM would be best. Failing that a portable aviation GPS is next best. That’s your backup or primary depending on your mission.
3) now get out that tablet. The ap on there will give you so much info it will make your life a doddle.

I fly an IFR capable machine with twin Garmin 430’s. Most of the time IMC or VMC I will be using a tablet for almost all my navigating and in flight data needs. I will be cross checking with the installed kit. But there is no way I would rely on the tablet in IMC. Twice I’ve had a tablet let me down, and both times were in difficult VMC. The first time I still have no idea why the app just kept shutting down. A NAV radio and a VOR saved the day. But the Garmin 496 in the panel confirmed my position. I’d never used a 496 at the time and didn’t intend to learn on my first flight in a new aircraft. The second time I had sat on the ground as a thunder storm passed and the tablet just would not fire up. I had to get from near Standstead to Dunkeswell on a day when even the airliners were diverting. A map and a compass got me home safe and sound that day.

I do worry about people who have no backup to a tablet.

Edit to add.
To clarify. If flying IMC I will have a NAV radio back up. But if I lost my GPS I would be straight onto the radio to advise a controller and ask for assistance even if only to keep an eye on me.
And someone is going to query the 99.99% number, we’ll its scientifically plucked out of the air so is beyond question.
Flyin'Dutch' liked this