RNAV vectors

"Sam Spade" wrote in message
...
Roger wrote:


And here I always though they were VOR offsets. Although I have to
admit it's been well over 10 years since I actually heard any one give
an RNAV off set. :-))
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Offsets are a feature in TSO 145/146 (WAAS capable) sets. The smart money
will use a slight offset to fly a Victor Airway to greatly reduce the
opposite direction mid-air potential. Minor offsets are already approved
on the North Atlantic.

Offsets should not be used for instrument approach or departure
procedures.

I thought Roger was talking about radial/DME offsets like used in KNS80 and
other RNAV boxes to define RNAV waypoints.

But course offsets were a feature of my old Northstar M3 IFR GPS. Not
mandated by TSO back then, though. I noticed the course offsets in the
GNS430W while reading the manual and wondered why they appeared.

Hard to imagine the FAA mandating course offsets to avoid center-of-airway
conflicts, given the following:

§ 91.181 Course to be flown.
Unless otherwise authorized by ATC, no person may operate an aircraft within
controlled airspace under IFR except as follows:

(a) On a Federal airway, along the centerline of that airway.

(b) On any other route, along the direct course between the navigational
aids or fixes defining that route. However, this section does not prohibit
maneuvering the aircraft to pass well clear of other air traffic or the
maneuvering of the aircraft in VFR conditions to clear the intended flight
path both before and during climb or descent.

Stan Prevost wrote:
"Sam Spade" wrote in message
...

Roger wrote:

And here I always though they were VOR offsets. Although I have to
admit it's been well over 10 years since I actually heard any one give
an RNAV off set. :-))
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Offsets are a feature in TSO 145/146 (WAAS capable) sets. The smart money
will use a slight offset to fly a Victor Airway to greatly reduce the
opposite direction mid-air potential. Minor offsets are already approved
on the North Atlantic.

Offsets should not be used for instrument approach or departure
procedures.


I thought Roger was talking about radial/DME offsets like used in KNS80 and
other RNAV boxes to define RNAV waypoints.

But course offsets were a feature of my old Northstar M3 IFR GPS. Not
mandated by TSO back then, though. I noticed the course offsets in the
GNS430W while reading the manual and wondered why they appeared.

Hard to imagine the FAA mandating course offsets to avoid center-of-airway
conflicts, given the following:

§ 91.181 Course to be flown.
Unless otherwise authorized by ATC, no person may operate an aircraft within
controlled airspace under IFR except as follows:

(a) On a Federal airway, along the centerline of that airway.

(b) On any other route, along the direct course between the navigational
aids or fixes defining that route. However, this section does not prohibit
maneuvering the aircraft to pass well clear of other air traffic or the
maneuvering of the aircraft in VFR conditions to clear the intended flight
path both before and during climb or descent.


The essence of that regulation was written in the 1950s. Anyone flying
..10 n.m off centerline would not even be noticed. (608 feet).

On Thu, 21 Dec 2006 08:41:10 -0600, "Stan Prevost"
wrote:


"Sam Spade" wrote in message
...
Roger wrote:


And here I always though they were VOR offsets. Although I have to
admit it's been well over 10 years since I actually heard any one give
an RNAV off set. :-))
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Offsets are a feature in TSO 145/146 (WAAS capable) sets. The smart money
will use a slight offset to fly a Victor Airway to greatly reduce the
opposite direction mid-air potential. Minor offsets are already approved
on the North Atlantic.

Offsets should not be used for instrument approach or departure
procedures.

I thought Roger was talking about radial/DME offsets like used in KNS80 and
other RNAV boxes to define RNAV waypoints.

He we-)) As in LAN 27015 (I think that was the way they were
worded) Actually I filed an RNAV offset coming out of OSH a few years
ago when MTW VOR was out of service. I used an offset from GRB that
was very close to MTW. The clearance sounded something like OSH
direct GRB17025 Direct LDM, Direct 3BS(I don't remember the numbers
now but that conveys the general idea)



But course offsets were a feature of my old Northstar M3 IFR GPS. Not
mandated by TSO back then, though. I noticed the course offsets in the
GNS430W while reading the manual and wondered why they appeared.

Hard to imagine the FAA mandating course offsets to avoid center-of-airway
conflicts, given the following:

§ 91.181 Course to be flown.
Unless otherwise authorized by ATC, no person may operate an aircraft within
controlled airspace under IFR except as follows:

(a) On a Federal airway, along the centerline of that airway.

(b) On any other route, along the direct course between the navigational
aids or fixes defining that route. However, this section does not prohibit
maneuvering the aircraft to pass well clear of other air traffic or the
maneuvering of the aircraft in VFR conditions to clear the intended flight
path both before and during climb or descent.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Sam Spade wrote:
Offsets are a feature in TSO 145/146 (WAAS capable) sets. The smart
money will use a slight offset to fly a Victor Airway to greatly reduce
the opposite direction mid-air potential. Minor offsets are already
approved on the North Atlantic.

The CNX-80 has offsets. I didn't realize they were required by the TSO.
The story I had heard was the CAP wanted offsets so they could fly box
search patterns, and Apollo put the feature in to close a big sale to them.

Roy Smith wrote:

Sam Spade wrote:

Offsets are a feature in TSO 145/146 (WAAS capable) sets. The smart
money will use a slight offset to fly a Victor Airway to greatly reduce
the opposite direction mid-air potential. Minor offsets are already
approved on the North Atlantic.


The CNX-80 has offsets. I didn't realize they were required by the TSO.
The story I had heard was the CAP wanted offsets so they could fly box
search patterns, and Apollo put the feature in to close a big sale to them.

More than you ever wanted to know:

2.2.1.3.16 Parallel Offsets

The parallel offset is defined as a route parallel to, but offset from,
the original active route. The basis of the offset path is the original
flight plan leg(s) and one or more offset reference points as computed
by the navigation system. The computed offset reference point is located
so that it lies on the intersection of lines drawn parallel to the host
route at the desired offset distance and the line that bisects the track
change angle. An exception to this occurs if there is a route
iscontinuity (or end of route). In this case, the offset reference
point is located abeam of the original flight plan waypoint at the
offset distance.

The offset path and associated waypoint must be created to the same
standards as the host route. The earth model must be WGS-84 and the
offset reference point must have the same or better resolution than the
host route waypoint. The parallel offset function shall be available for
enroute TF and the geodesic portion of DF leg types at a minimum.
Note: The parallel offset function enables an aircraft to be flown on a
flight path offset from the center line of a route while maintaining all
characteristics of that flightpath, as if it were being flown centrally
on the route. Examples for the use of offsets are weather avoidance, air
traffic conflict avoidance, etc.The system shall have the capability to
fly parallel tracks at a selected offset distance.

When executing a parallel offset, the navigation mode and all erformance
requirements of the original route in the active flight plan shall be
applicable to the offset route. The system shall provide for entry of
offset distance in increments of 1 nm, left or right of course. The
system shall be capable of offsets of at least 20 nm. The fact that the
system is operating in offset mode shall be clearly indicated to the
flight crew. When in offset mode, the system shall provide reference
parameters (e.g., cross-track deviation, distance-to-go, time-to-go)
relative to the offset path and offset reference points.

An offset shall not be propagated through route discontinuities,
unreasonable path geometries, or beyond the initial approach fix.
Annunciation shall be given to the flight crew prior to the end of the
offset path, with sufficient time to return to the original path. Once a
parallel offset is activated, the offset shall remain active for all
flight plan route segments until removed automatically, until the flight
crew enters a Direct-To routing, or until flight crew (manual) cancellation.

Note: RTCA/DO-236A provides additional information on parallel offsets.

Dan Luke wrote:

Anybody ever get vectors to final for RNAV approaches?

Yes, I have been offered vectors to final for an RNAV/GPS approach a few
times in both the northeast and mid-Atlantic (US) areas. In all cases I
declined the offer and instead requested vectors to a specific IAF.

These days I even save the back and forth game by including the direct-to
IAF request within my first call to the facility.

"Bonanza XXX, level 5000 with current weather, requesting RNAV/GPS 24
approach Dunkirk and requesting direct IYZZY (some crazy IAF name) when
able."

--
Peter

"Peter R." wrote in message
...

Yes, I have been offered vectors to final for an RNAV/GPS approach a few
times in both the northeast and mid-Atlantic (US) areas. In all cases I
declined the offer and instead requested vectors to a specific IAF.


Why request vectors to an RNAV (GPS) IAF?

"Dan Luke" wrote:

Anybody ever get vectors to final for RNAV approaches?

Sure. And what's so cool about the internet today is that not only can I
show you the chart for the approach
(http://204.108.4.16/d-tpp/0612/00286VDG24.PDF), I can also show you how we
flew it
(http://flightaware.com/live/flight/N...953Z/KHPN/KPOU)
.. Now all we need are the ATC tapes and a webcam sitting on the pilot's
shoulder :-)

On the other hand, I'm not sure if a "... or GPS ..." approach is quite the
same thing as a "RNAV GPS ..." approach.

"Roy Smith" wrote in message
...

Sure. And what's so cool about the internet today is that not only can I
show you the chart for the approach
(http://204.108.4.16/d-tpp/0612/00286VDG24.PDF), I can also show you how
we
flew it
(http://flightaware.com/live/flight/N...953Z/KHPN/KPOU)
. Now all we need are the ATC tapes and a webcam sitting on the pilot's
shoulder :-)

On the other hand, I'm not sure if a "... or GPS ..." approach is quite
the
same thing as a "RNAV GPS ..." approach.


No, RNAV approaches have RNAV in the name.

Steven P. McNicoll wrote:
"Roy Smith" wrote in message
...

Sure. And what's so cool about the internet today is that not only can I
show you the chart for the approach
(http://204.108.4.16/d-tpp/0612/00286VDG24.PDF), I can also show you how
we
flew it
(http://flightaware.com/live/flight/N...953Z/KHPN/KPOU)
. Now all we need are the ATC tapes and a webcam sitting on the pilot's
shoulder :-)

On the other hand, I'm not sure if a "... or GPS ..." approach is quite
the
same thing as a "RNAV GPS ..." approach.



No, RNAV approaches have RNAV in the name.



A lot of the older ones have just "GPS" (as opposed to "or GPS). The
ones that say "GPS Runway 8" (for example) are RNAV IAPs.