Lateral offset FMC 777

[777 orion]

Hello everybody,

After crossing a few times the Atlantic i found myself thinking about the lateral offset procedure and came up with a question,

On the 777, when doing the lateral offset on the FMC, with LNAV engaged, obviously, what protects us from forgeting to remove the offset, and descend and perform a star and VOR on LNAV offset?

Do we have any kind of protection bellow a certain height or any other reminder besides the "offset" light in the FMC?


Thanks

[oceancrosser]

Well, you should remove the offset no later than leaving the Oceanic Area. That should'nt be beyond the average pilots capabilities. Any direct clearances, such as often given by Gander Control or Scottish/Shannon on the other side will cancel the offset. Basic systems knowledge.

[burgerbun]

Next time you re offset, check the route in the plan mode. I think you ll see the offset ending where the star begins

[underfire]

Yes, there are several points that will automatically remove the offset. The FAF is one of them.

[SMOC]

Yes SIDs and STARS will not accept offsets.

However entering a direct to and executing on a SID will then allow an offset to be entered. (China often give an offset during the SID). It may work on a STAR as well.

[JeroenC]

Don't know about the 777 but on the 737 you can give an offset termination waypoint.

[fmcinop]

The 777 does not have the end offset at waypoint X function that the 737 has.

The offset light is impossible to miss though. There is no was you would miss it.

[777 orion]

Thank you all for your answers. Apart from the "average pilot capabilities" comment from the Ocean Crosser, all were usefull.

I will try the Burgerbun good sugestion next time.


Thanks

[flyboyike]

Yes, there are several points that will automatically remove the offset. The FAF is one of them.


Little late by then, ain't it?

[underfire]

Actually flyboy, no, we use offsets to 'create' the effect of multiple procedures, and mvd, while ATC only has to manage one set of waypoints...

the offsets, especially when used on curved transitions to the FAF, automatically transition very nicely to the straight in final approach.

The 777 FMC is really an anomoly, not sure why, but has/doesnt have many capabilities of other Boeing ac...

[flyboyike]

That's interesting. Two airlines, seven years, four airplanes, never used the offset feature once.

[burgerbun]

Used a lot in China, they always want us 3 miles right off track, and also great for weather deviations.

[selcalcheck]

Hi gents,

In my present airline we do have an SOP to follow after leaving the last OCA WP.
It is conteined in a dedicated check-list to be read. "Lateral Offset...check".
It is the ONLY way to remind the crew about it.
Anyhow at the end of crossing (both ways) ATC always direct you to a specific WP so that the offset is automatically canceled.

Happy offsets!

[underfire]

It really is a great feature to work with.

With use of RNAV and RNP STARS, Enroute, an initial/intermediate legs, it allows ATC to manage on set of waypoints with an offest. The ac will fly it perfectly.

As noted, if you are RNAV or RNP, and you need to deviate for weather, offsets are a great way.

Unfortunately, different ac configurations handle offset differently. With the 777, you are limited the min offset of 1 nm, which is great for enroute/STAR, perhaps initial, but intermediate segment is tough.

[JammedStab]

Used a lot in China, they always want us 3 miles right off track, and also great for weather deviations.

Have done a 12 mile offset in China.

[casablanca]

@Jammedstab......I had a controller assign us 25 miles Romeo side of track in China...reconfirmerd this twice and then went ok....whatever works
@Flyboylike......Some countries like China just assign you an offset.
Normally oceanic crossings and areas that follow the IFBPs recommend 1-2 miles right of track . However if just flying in the USA or Europe it is not used much.