rapport d’un écart longitudinal sur un rapport vertical

19:50 Jul 18, 2014 

yes, the other poss seems to be "cross-track deviation" (lateral), "along-track deviation" (longitudinal)... but there doesn't seem to be an "up-and-down-track deviation"...

13:28 Jul 18, 2014 

It does seem to be the case given the context.
I've also seen "écart longitudinal" translated as "along-track" in this context, e.g.:
tolérance d'écart longitudinal
along-track tolerance

However, I cannot see how this helps much with the present sentence.

ref:
http://www.btb.termiumplus.gc.ca/tpv2alpha/alpha-eng.html?la...

13:15 Jul 18, 2014 

What sort of system are we talking about e.g. as per http://en.wikipedia.org/wiki/Category:Aircraft_landing_syste... ?

10:17 Jul 18, 2014 

Yes, I know what you mean. DLyons answer could work as well, though it does depart from the source text a bit, though the meaning is ok. It depends upon what they want to say in the patent, and it looks like they want to keep the meaning a bit ambiguous.

No, not a direct relation to the famous Scott-Moncrieff - the Scott-Moncrieffs are a different branch (http://en.wikipedia.org/wiki/Clan_Moncreiffe).

10:00 Jul 18, 2014 

I'd personally have a bit of difficulty squeezing "vertical position" out of "rapport vertical de la position" in a patent, particularly as this wording occurs more than once. The diagrams accompanying the patent don't throw any light on it (and Proz doesn't seem to have any way of uploading images). By the way, I have to ask: with a name like yours and being a French translator, are you in any way related to the renowned Scott-Moncrieff, of "A la recherche" fame???

09:37 Jul 18, 2014 

It's a bit difficult to be sure without seeing the photos.
Would "defined by the ratio of the longitudinal deviation to the vertical position of the aircraft relative to the said touchdown point" make more sense..?