Hi all,

The AIP states if a GNSS is certified to TSO C-129, navigation to a destination alternate aerodrome must be planned using a navigation system other than a GNSS.

Is this saying that I actually need to use the ground based aid to track there? Or is it simply a precaution? Also, is the reason why an alternate is required for this particular type of GNSS simply due to it being less reliable?

In regards to Night VFR, the AIP says an alternate must be provided within 1 hours flight time of the destination if I don't have the required equipment on board to navigate there. But in Part 91 MoS (Chapter 26, para 26.07, it says an aeroplane for a vfr flight at night must be fitted with an approved GNSS or an ADF or VOR.

I'm confused as to why the alternate requirement exists for night vfr. If the equipment must be fitted, then doesn't that mean you will always have it available?

The 129 GPS is considered to have insufficient integrity to be a sole means of navigation. You can use it, but you must always plan for it becoming unavailable. Note that nobody said it was less accurate - just less trust worthy.

Also there is no such thing as a Night VFR instrument approach. ALL approaches under the night VFR are, by definition, VISUAL APPROACHES.

If you have any doubt about being able to do a visual approach, you have no business planning night VFR in the first place.