Sometimes after programming a flight on the FMC I do not observe a T/C and T/D on the ND flight path.  There must be something I am doing wrong that causes this but I have not isolated the cause yet.  On a recent flight I saw a S/C point.  Anyone know what that is? 

Thanks for any help!
simboy_al

SC = Step Climb point

If youre using v4.4 you can erase a waypoint in your flightplan, then click abort or cancel or whatever its called in the MCDU instead of confirming the deletion of the waypoint. This should cause the FMS to recalculate your vnav profile again. This only works with v4.4, it does unfortunately not work with v4.6

Ive been using a third party app to do my flight plans and then import them in to the 757 ( through the flight plan loader in the cdu ) and so far ive had T/C and T/D show up all the time and its been smooth flying except for that flight where i landed a bit to hard and one of the landing gear collapsed 

My impression is that you in some cases have to enter the desired altitude and speed for the last waypoint, otherwise the TD is not computed. As you mentioned it works great for some transitions and arrivals, but i believe it only does if there is a real altitude/speed restriction.. even if there are restrictions for Below(B)/Above(A) it will not compute the top of descent. I'll assume that this is a bug.

I have no idea why the TC is not computed.. maybe the FMC preflight is not complete? I always ensure that the FMC writes "preflight complete" so everything is for sure done.

/Bo

Markoz wrote on Aug 6^th, 2012 at 6:27am:


Im using AivlaSoft EFB, Well im using a demo of it to see if i like it before i buy and i use that to export to the Microsoft pln format which the cdu can read from. I have to complete the finial approach, well normally i do to make sure i get the runway i want.

But any flight planner that can export to the pln format will do

Markoz wrote on Aug 6^th, 2012 at 9:55am:


I don't know why i wrote "real".. Of course any altitude restriction will work except for below/above, as we already clarified is true.

Markoz wrote on Aug 6^th, 2012 at 9:55am:


Hope it will get fixed.. Pretty easy computing the distance from the last waypoint to the airport and then add the expected flightlevel based on a 3 degree standard glide slope, to the last waypoint (of course this should be overriden, because your approach is not likely to be straight in, but it gives a good guess, like most other FMCs does it), and of coruse above and below levels should be taken into account.

/Bo

Hi Mark,

I think i have a theory why the T/C and T/D dont always show on some flight plans, I have flown so many flights with the 757 over the past week while 99% of flight plans have worked today i have the 1% that does not.

My theory is that the flight plan we are following is not complete in the Navigraph data that the 757 has, while we enter the legs we need and then follow the star or sid, there is a hidden discontinuity in the Navigraph data with means it cant complete the flight plan and work out the T/C or T/D. I believe the old 4.4 fmc worked out the issue regardless of this hidden issue with the flight plan so it always showed the T/C and T/D.

EFB got me thinking about the issue as i noticed some flight plans it would have a DTC ( discontinuity ) on part of the route and if i imported a flight plan in to the 757 cdu with the DCT it would not work out the T/C or T/D which i would normally then fix so that does not happen as i would be picking the wrong sid or star in the flight plan.

With my current flight plan, GCTS to GMFF it causes a DCT with can not be fixed in EFB i think so i dont have the T/D in the cdu when i select ILS27 for the runway and FES for the transition, if i select 27 as the runway with no markers for ils or transition then it works out the T/D correctly.

Back to the ILS approach with the transition of FES if i take out the middle ils runway marker it then fixes the the flight plan

On the flight plan i have atm it would be,

DONAS ( this is the last part of the flight plan before the star would normally be needed )
( This is where the DCT is in the flight plan in EFB )
FES ( the transition as there is no star for the airport )
D074L ( GPS marker for the approach )
CI27 ( GPS alignment for runway heading or what ever it does )
FI27 ( Same as above )
RW27 ( the runway )

If i take FI27 out of the flight plan it fixes the T/D and does not break the flight plan i have chosen like it was before. I cant explain why removing an approach waypoint would fix the whole flight plan and allow it to complete with the T/D and proper fuel calculations though but it does seem there is a few ways to break the flight plan and one of them is choosing the wrong sid or star which seems to be something im good at but i do fall back on pdf charts as well when nothing makes sense to me.

Just a theory mind you

Makes Sense i use Fs2build  so i will investigate that as well .