"Teacherjh" wrote in message
...

The applicant is supposed to demonstrate knowledge of the differences
between nonprecision approaches (NPA), approaches with vertical guidance
(APV), and precision approaches (PA). However, there appears to be no
requirement to fly an APV even if the aircraft is equipped to do so.


That's new to me. What is the difference between an APV and a PA? I
thought
"precision" meant "with vertical guidance". (never much agreed though)

Precision approaches are provided for under ICAO 10, whereas APV approaches
are addressed in ICAO 6. According to AIM, an APV is an approach with
lateral precision, but which is not precise enough vertically to be called a
precision approach. An APV may provide glideslope information, but to higher
minimums than a precision approach. An LNAV/VNAV, LNAV, and LPV approach are
all APV approaches. Salem, OR, for example, has an RNAV GPS approach with
LPV (ch. 38000). Flying these approaches is considerably different from what
most of us are used to. The approach plates contain all kinds of different
information (the ch. 38000, for example) and the approaches themselves have
different rules about how they are flown.

The WAAS GPS used to fly these approaches also behaves differently from an
ordinary approach certified GPS. The terminology is even different. The FAF
becomes the FAWP and the MAP becomes the MAWP. The WAAS unit, unlike GPS,
automatically cycles to the next waypoint at the MAWP. Also unlike GPS,
inside the FAWP the WAAS does not show linear course deflection but angular
course deflection like a localizer, becoming more sensitive as you get
closer -- to a point. Then it switches to linear course deflection when the
total course width becomes 350 feet wide (that would be one dot deflection
equals 35 feet), whereas the width of the localizer course at the approach
end of the runway is dependent on runway length. Also, on long final
approach segments the course deflection is linear when that is more accurate
than the angular deflection that would be provided by a localizer when you
are still a long way from the airport. The WAAS scale also differs
considerably from that of GPS on the missed approach.