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Old 23rd Jan 2017, 15:43
  #33 (permalink)  
terry holloway
 
Join Date: Jul 2005
Location: cambridge
Posts: 187
Originally Posted by riverrock83 View Post
Firstly - you can't put unpublished GNSS approaches into IFR GPSs - they simply wont accept them. Its part of their certification.

So you are left with doing home brew approaches based off VFR GPSs or other navigation beacons.

A let down over the sea is still pretty safe. CFIT isn't a risk, so long as your altimeter is set. If you can get a traffic service from ATC, all the better.

Over land - your minimums are going to be pretty high for an unpublished approach. It doesn't take a rocket scientist to descend on a radial after crossing a VOR / beacon.

I wouldn't use GPS/ILS or some other app to go anywhere near the sorts of minimums I would on a published approach using a certified GPS. GPS altitude ambiguity and other issues (no alarms from a phone when it isn't getting an accurate GPS fix) mean it shouldn't be trusted, certainly for height info.

Some CAT operations have had their own approaches for years (I believe that there are unpublished GPS based approaches to places like Barra in use) but those are professionally created.
"A let down over the sea is still pretty safe"
Is "pretty safe" a positive or a negative statement? It's either safe or unsafe, and MSA is MSA whether you are over sea, land, or mountains which run down to the sea!!
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