Need a 2nd nav with GNS 430?

wondering if a 2nd nav is really a necessity with a GNS 430 in the panel.

Don't put all your eggs in one box.

1: the display fails, you're toast. HYBT
2: RAIM error in IMC is also inconvenient. BTDT
3: if you can't update the database (such as you're in the middle of a
trip during the window) you can't do IMC anymore. BTDT - at Sun'n'Fun,
no less.
4: you're in some bumpy clouds, reach over to switch off the strobes or
switch on the pitot heat or something, and a bump causes you to hit the
master. Oops - flip it back on. VORs come right back. NAV comes right
back. ADF comes right back. DME comes right back. GPS begins to
acquire satellites, do its self test, and waits for you to push the
lawyer button before continuing. Meanwhile, you're doing 150 knots in
the soup and just got an amended clearance. BTDT
5: New clearances are often easier to dial into a VOR to start with, so
while you push the GPS buttons you're at least flying the clearance. BTDT
6: If you have an electrical failure in IMC, you may need to decide
what units to leave on the battery and what units to shut off. I don't
know the 430's current draw; you may be better off with just a single
VOR in some cases (though I wouldn't be surprised if the old VOR
receivers draw more than the new GPSs). BTDT, though without the 430.

That's just a start.

Jose
(r.a.h retained, though I don't follow that group)
--
Get high on gasoline: fly an airplane.
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