Originally Posted by Doug E Style
OK, I know the issue of CTOTs has appeared here before but despite searching, I've not found anything yet relating directly to the following so hopefully some clever ATC people will be able to shed a bit of light here. I've been flying into Heathrow frequently for about a year now and thought I had a reasonable idea of the principle of CTOTs (ie. to absorb holding delays on the ground in this case). However, something happened recently that has puzzled me. On three consecutive days I was operating our company's first flight of the day into Heathrow from another major European airport and each day we were given a CTOT due to Heathrow inbounds (there were no weather issues on any of these days) which amounted to a delay of between 20 and 30 minutes over the three days.
On the first day we were allowed to take off 5 minutes ahead of the CTOT and we held for eleven minutes.
On the second day we took off 2 minutes after the CTOT and we held for thirteen minutes.
On the third day (due to congestion at the departure field) we took off 10 minutes after the CTOT and we held for 15 minutes.
Now, I appreciate the complexity of managing air traffic and the dynamic nature of the business but from these events, it seems to me that there is a very wide time margin involved here. Whether we hit the slot, were early or late does not seem to have made much difference. Had our slot been ten minutes later in each case above, would our holding have been reduced by ten minutes also? I suspect not.
I am not criticizing anyone here; I have immense respect for the UK's ATCOs but I would like to understand the system a bit more than I do at present.
Thanks.
I'm afraid I doubt there is any rhyme or reason to flow into LHR. I guess that most of the day they put more planes in per hour than can actually be accomodated. Then when you arrive there is ground congestion.