Chiglet
Your point is one of my biggest bug bears when Airline and Ground Handling agents are aware of CTOT's and don't pass them onto crews. Also when crews that have been made aware of their CTOT by ATC, still think they can make their slot by requesting push and start at or after the CTOT time.
Crews/Ops/Dispatchers:
The -5/+10 is a tactical tool for use by ATCO's when aircraft are caught in a queue at the hold or are ahead of aircraft with similar CTOT's. Please do NOT get ar$ey on the RT when we tell you we cannot get you started and airborne in time. ATCOs and ATSAs have other things to be doing than begging to FMP and using our ace cards when we really need them for guys AT THE HOLD!
My advice to crews is always to check in with Ground (or Delivery) no later than 10 mins before your CTOT or EOBT if it looks like you are running late. The controller can then tell you your latest CTOT (if any) and if there is a chance of you getting away or not in the current traffic situation. If the answer is not favourable, at least you can then have comapny send a DLA or re-negotiate a new CTOT, and as soon as you are fully ready a REA can be sent. I find that this very often triggers a slot improvement fairly quickly rather than getting into the relams of Missed Slots being dealt with after CTOT.
Finally with regard to EOBT tolerance for HCS, PLEASE PLEASE PLEASE do try and get company to update your EOBT if it is outside -/+15 mins. This is primarily for FMP forecast purposes and helps to avoid ATC Sector overloads. Although ATC are able to send a DLA, it is not our responsibility to do so (we are not really supposed to amend flight plans not originated by us), and is normally done out of the goodness of our hearts if:
a) We are not busy AND you have tried and failed to get any joy out of company.
b) The new EOBT is only a few minutes out (NOT 30 mins or more!!)
c) We don't get our heads bitten off if a CTOT is then issued based on the new EOBT.
Again, my top tip is to get onto company as soon as you know you are going to be early or late on your EOBT and keep the plan fresh. Nothing worse than having to do the same thing with the doors closed, tug attached and ready to go. Remeber to go early on your EOBT -15, the plan has to be refiled in toto.
Some companies are better at this than others, but the only way they will all get the message is if crews keep the pressure on them from first contact on "Company" inbound, to perhaps a quick check as boarding is completing before the "Before Start" checks!