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-   -   Lateral Offset (https://www.pprune.org/tech-log/510980-lateral-offset.html)

FlightPathOBN 23rd Mar 2013 19:42

Lateral Offset
 
Does anyone know how or where to enter a lateral offset other than L1-L5 whole miles?

I am looking for offsets in the 0.1 to 0.5nm range.
Would be for RNAV/GPS/RNP procedures.

FE Hoppy 23rd Mar 2013 20:19

What FMS type?

749CONNIE 23rd Mar 2013 20:25

Prog page 2 for RNP of .3 for a RNAV approach. Feet wet out of China you'll get 5, 10, or 15 miles. No concept of three dimensions.

FlightPathOBN 23rd Mar 2013 22:28

FE,

Various, working with 777 and Smiths right now, but in general...

I can get to the Lateral Offset page with L1-L5, but thats it, not sure if there is a trick with POS shift, or other way to get offset from centerline of 0.1nm R or L...

Trying to get an offset R or L in RNAV, GPS, or RNP...

mutt 24th Mar 2013 05:38

From what i understand from a course last week, only certain FMS types will permit 0.1 0.2 etc, others are stuck at 1.0 2.0. So quite possible 777 FMS won't do what you are asking.

Can I ask why you are trying this in RNAV, GPS, or RNP ? If the goal of these procedures is to increase accuracy, isn't your idea of offsetting working against that?

Offset for cruise, SLOP is a different thing.

Slasher 24th Mar 2013 05:57

China feet dry is usually 2 or 3 miles. Feet wet as per Connie's
post. NEVER been asked an offset with a decimal point. Might
look it up though for the froggy suck-squirt.

FE Hoppy 24th Mar 2013 08:38

Honeywell FMZ and Collins GNLU 910 will accept decimal offsets.

Slasher 24th Mar 2013 10:27

Ta. ................

FlightPathOBN 24th Mar 2013 16:06


Can I ask why you are trying this in RNAV, GPS, or RNP ?
What I have designed is a single RNP or RNAV procedure that will work for a multi-variant platforms, rather than a specific procedure for each aircraft class/type. This way, ATC only has to know one set of waypoints, rather than multiple sets.

As an example, with a turn to final, one procedure would make everyone drive the A380/747 track, so the 737 drivers would fall asleep on final. :}

With the offsets, the A380 can offset to the outside, while the 737 can offset to the inside. The offsets can be set to release at the FAF for the straight in, but the box I was working with, the HW, automatically removed the offset when encountering a FAF waypoint.

As noted, this worked with my test platform and flight val.

I have an airline with the 777 platform, with a Smiths box, and does not allow for anything less than whole nm offests...(than I can figure out)


Honeywell FMZ and Collins GNLU 910 will accept decimal offsets.
Thanks Hop for the information...

FE Hoppy 24th Mar 2013 19:33

Many FMS will not allow offset on procedures. The honeywell for example will automatically cancel any offset when the first STAR waypoint becomes active.

misd-agin 24th Mar 2013 20:34


As an example, with a turn to final, one procedure would make everyone drive the A380/747 track, so the 737 drivers would fall asleep on final.
737 would be at 45 degrees of bank attempting to fly their ground track. :sad:

FlightPathOBN 25th Mar 2013 14:44


737 would be at 45 degrees of bank attempting to fly their ground track.
???

An A380 needs a 4nm radius turn, while a 737 only needs a 2 nm radius turn..

a 737 on a 4nm radius turn is only about 5 degrees bank angle...

galaxy flyer 25th Mar 2013 15:55

I think you need to post the TAS you are using for different types.

FlightPathOBN 25th Mar 2013 16:05

Why would you need TAS? The aircraft flys the procedure, and is bound by the leg speed or other restrictions...I can put a 3.5nm radius or a 10nm radius....it does not fly one faster because it is a smaller radius.

Look at the RNP procedures in Canada with WJ, you will see short finals with the 737NG with 1.5nm radius RF legs, that is the bank limit of 25 degrees. (with 50 kt tailwinds)

I have already done this with RNP procedures several Airbus variants ...The 777 with the Smiths does not...

The question was which FMS type can do an offset less than 1nm.


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