View Full Version : top of descent how to show in zulu time on 747-400 FMS??

6th Jan 2002, 15:29

Can anyone tell me how to show the ETA for Top of descent in the 747-400 FMS??
1. Is it through the FMS fix page???
2. Or the progress page??

Thank you.

spoilers yellow
6th Jan 2002, 21:10
It should appear on Progress page 1. along with the distance to go to TOD.

7th Jan 2002, 09:04

I don't know any easy way via the FMC - after loading an arrival you could step throught the later legs in PLAN on the ND, then guestimate a position (waypoint -nn miles) to enable you to monitor it on the legs page.

If you have access to the ACMS, it's there as a time to run to TOD or use the mneumonic "timtotod". Recall this ACMS info is navbl until after 400nm from departure.

As I understand it, dist to and ETA TOD only appear on Prog 1 wi 200nm of TOD - it replaces TOC and step climb data.

<img src="smile.gif" border="0">

7th Jan 2002, 13:08
Once you're at your final cruise level and you've loaded an arrival, on the fix page enter a level 100 feet lower than your present level eg FL389 if you're at FL390 and the FMC will then give you a position on the ND and an ETA for a position as near as dammit to TOD. The ETA and dist to run to TOD will also be on Prog 2 as Spoilers Yellow has said. <img src="wink.gif" border="0"> :)

Willit Run
7th Jan 2002, 21:08
After the recent events involving big transport airplanes, is it really appropiate to be dispensing technical information over a non secure site to folks unknown to you?

What a good way to get tips and tricks to fly a 757 or program a 747 for a decent all by itself.

I don't know, just a concern from someone who wishs my GPS had VNAV.

7th Jan 2002, 22:17
Good question - lots of variables. I can only give you the real data on the B777 system (Pegasus FMC), but if my memory serves the 744 is very similar, if not the same.

For those not familiar with the FMC system on these airplanes, the pages under discussion below are PROG(ress)-1 (page 1) and FIX. The data on PROG-1 is in the bottom right hand segment - when appropriate.

Some rules for PROG-1 (R3-R6):

1. No TOD data are displayed if no approach has been programmed.
2. In the climb segment Climb Data are displayed. Distance to TOC / Time etc
3. In the Cruise Segment, if a Step Climb is forced on the LEGS page(s) or a Step Climb is predicated by weight and ISA/WIND (and a 0 is not inserted into the STEP perams) then Step Climb distance to Go / Time block is displayed.
4 Otherwise the area is blank.
5. If (1) above is true and the Distance to Go (DTG) [To Destination R/W] is &lt;=500nm then a TOD block is displayed with Distance to TOD and Time.

Item 5 is an interesting one. I have never seen a software routine that uses distance to TOD as a function trigger (for the TOD Block display) on either the Smith's or the Honeywell units. However there are a large number of operators out there who think this is the case. The 777 and (I believe) the 744 both use 500 DTG (to Dest) as a trigger for this info display. Both are Honeywell's in my experience and the 777 uses a Pegasus (fact) and the 744 uses the PuP software (Not certain). If anyone knows otherwise - I would be interested to hear about the fit. The 767 / 757 series use another value (300 nm?) but this is still DTG for Destination rather than TOD point.

So that is half of the question. Resolving a TOD time / Distance prior to 500nm to go takes a little more work. As was stated above, the ACMS can be interrogated - if you have it / access. However a more generic solution is :

1. Programme the approach
2. Using the PLAN mode and STEP on the LEGS page, move forward so that the TOD GREEN ring is displayed. (do this on the other guys FMC - you will see why later).
3. Using the DATA display mode, take a guess on the time from the preceding and following waypoints. Insert this TIME with the suffix "Z" into the 6R (bottom right) entry on a FIX page on your side. Play with this as required until the FIX doughnut overlays your TOD doughnut.
4. The FIX page (6C) will now display Distance to Run and ETA of that point.

With 2 FIX pages to play with, this is quite a useful (and under used feature). Another way to get the (almost) correct figure is :

1. On the FIX page, insert into 6R an altitude 100ft lower than your present cruising altitude.
2. This will then display a time and distance for that anticipated point - just after TOD.
3. Subtract a minute and put that time into 6R if you want to be nearer the mark. Although at any great distance a minute is hardly an issue !!

Hope this helps


7th Jan 2002, 22:40
Explorer missed an update here I fear. Never Mind.

Willit Run - I think "they" would need a bit more than this info to do anything worrying. Anyway this is all public domain stuff, nothing sensitive or even very clever. What can we do ? Shut down all flying schools, stop selling MS Flight Sim, ban the wheel, ban books?

I am not trying to be funny here, just practical. Information needs to be shared or it is worthless. Someone asks a decent, reasonable question that we have an insight on - we (and I am sure I speak for most) will answer it if possible.

Someone asks how to programme a Vne dive to a specific Lat/Long would not be accorded the same civility. Rather, I hope, a visit from the local Feds.


8th Jan 2002, 03:44
I'd like to know your references for the statement that TOD info is triggered by 500nm DTG to dest in the B744.
By experience, TOD data on Prog 1 appears about 190-195nm to TOD. That equates to about 350nm max to dest. I have never seen more than about 190 dtg TOD on prog 1.
BTW, I, too, fail to see how this info can help the "bad guys".