Some interesting comments in this thread. (I note that the following summarises a number of comments made by others) -
would these be invalidated if you started your take off run say 309m earlier
I can't bring any situation of concern to mind. Of course, one might choose to redo the sums but using the original calculations will produce acceptable data for the new starting position for the takeoff. Caveat - if there is a turn required, then the commencement of the turn/configuration and speed changes have to remain at the same point/sequence so that lateral terrain clearance is not a problem.
When this cone is moved back, it is possible to "capture" an obstacle that was not considered from an intersection departure.
Not really a concern. The splay starts at the end of the TODA. The only problem, then, is how do you achieve that starting point when you can't track visually, realistically, for a jet ? Always a vexed question. A tad easier since the days of GPS and very accurate FMS tracking capabilities.
Your V1 is essentially out the door
Only to the extent that it now becomes non-optimised for the takeoff. One can either redo the sums or accept a conservative set of takeoff data.
Now you’re forced to take a sick puppy airborne.
If this is seen to be a concern, one redoes the sums.
I think his point here was that the performance was calculated and the aircraft perfectly capable of an intersection departure, so he didn't NEED a backtrack.
Indeed ... but, were I to end up in an accel-stop, might I appreciate the additional (new) fat in the actual ASDA ?
And yet I have actually seen this difference in the Engine Out Acceleration Altitude (EOAA) happen when comparing the takeoff data for full length vs intersection during preflight, so something changed. The explanation I gave is the one given to me by our training department.
I might be more interested in the comment had it come from the ops engineering SMEs ? Often the training folk, although well-intentioned and well-motivated, are not always across all the nitty gritty data.
there was a change to EOAA that needed to be accounted for.
What might be the objective basis for this statement ?
"If something were to go amiss during takeoff, would my choice of using the original intersection data be considered proper?"
I think so .. unless someone can come up with a technically sustainable concern.