FIX page ABEAM problem and ALTN page questions

[craig_read 43]

Hi,

 

I'm trying to put in some situational awareness into my flights so using the FIX and ALTN pages a little more than I did.  My plan was to enter my alternates etc.  I'll start the with the ALTN page question:

 

When entering an alternate and then selecting the details of that alternate the following data can be added:

 

WIND

ALT/OAT

 

This is basically the selected wind and OAT at a specific altitude, is there any logic used to select this altitude?  Should it be the altitude expected at that point in the plan or a closer to ground level altitude to give a view on surface winds?

 

ALT in the top right seems auto calculated, can someone tell me what this is?  I've looked in the FCOM and it says that it's an entry of any valid altitude or flight level into this line and it causes a recompilation of ETA and arrival fuel.  So for example if it was an ETOPS fuel and I was half way over the pond would my current cruise altitude be a good choice?

 

 

Onto the fix page, selecting ABEAM on a fix seems to be 'playing up'.  One I figured out what was happening and I was trying to select abeam on a point that was actually in my plan (my bad) so I totally understand why it was an INVALID ENTRY.  However there is another field I am using some 60nm from my track and when I attempt to select ABEAM it says "INVALID ENTRY" and I have no idea why.  Could it be because the perpendicular line probably intersects at a point where the aircraft is turning?  I would have thought it would cope with this.. is this how the real 777 behaves then?

 

Cheers

 

Craig Read

 

 

[rondon9898 84]

I was under the assumption that the ALTN wind referred to the wind on the diversion route from destination to alternate, which should be on the OFP, but cannot find the FCOM reference for it.

 

Edit: Yes the wind in the ALTN section is the average wind for the diversion route, so the ALT/OAT would be the planned altitude for the diversion routing.

 

Edit 2 (didnt read your post properly, soz!) yes, the ALT could be the current cruise altitude, but if you've had an engine failure or other malfunction, it may not be, or if you're close to the destination and are using the ALTN page for diversion contingency planning, you may wish to add the planned diversion alt from dest to diversion airfield.

 

Also, regarding your abeam points problem, as far as I know the FMC won't generate abeams for points on a departure or arrival routing or approach procedure, and won't generate for points more than 700nm away fm the aircraft. Might not help but it's all I can think of at the mo

[craig_read 43]

John,

 

Thanks for the replies will definitely look into the ALTN ALT selection etc.

 

BTW and just for your interest I got to the bottom of the ABEAM issue.  Apparently the problem was that the ABEAM point on the route was an arc i.e. a turning point at a waypoint.  When I put in a sudo point before it to make that part of the plan straight the ABEAM went in no problem.  This point was more than 700nm from current position so I think the restriction you mention isn't in place here.

 

Does anyone know if the real 777 does this?  I would have thought it could still do an ABEAM even if it was on a 'bend'...

 

Cheers