Latched

WetPink · 02-15-2008, 10:41 AM

Anyone know what it means when LATCHED is displayed on the top right corner of the flight plan page?

bfiek · 02-15-2008, 12:49 PM

I looked into this quite a while ago, and in the Honeywell manual it basically means the FMS is transitioning from one mode of VNAV to another. I know this doesn't completly answer your question, but since we don't use the VNAV capabilities of the box as much as we could, that's as far into it as I looked.

CSkyhawk72 · 02-19-2008, 09:59 AM

Thanks for the explanation, bfeik... I've been wondering the same thing for months and haven't been able to find a shred of info on it in any of our manuals.

WetPink · 02-19-2008, 10:27 AM

Normally SDP CMD is displayed, some times SDP INTV or LATCHED. The last two seem to affect the VPI in strange ways. So where does one find this Honeywell manual?

Yariv · 02-19-2008, 02:11 PM

those are all VNAV submodes as bfiek explained. they are not covered in the FMS manual. to explain the names of the modes based on the collins FMS, SPD CMD is speed command, where there is speed restriction at a fix and the vertical path is adjusted or abandoned to allow descending at this speed, SPD INTV is speed intervention, where the pilot changes the pre-planned speed using speed hold, and the vnav path has to be recalculated, and latched is when vnav is allowed to fly the pre planned path, speed, and descent angle. the fms still does all the vnav calculations even though vnav cannot be coupled to the flight director, so if you're actually following the correct path and on speed, you'll be latched.

glad to see people are using the vnav info! it's one of the best/best hidden tools the fms has to offer. teach everyone you fly with how to use it.

WetPink · 02-24-2008, 02:19 PM

So if I intercept a 4* slope at vmo/mmo (or whatever is in the pref int), LATCHED should be displayed? This does not always seem to be the case.