Today 4 aircrcaft were not ready at a busy summertime hold when I was on tower. They do not always say "sorry, I
ed up and didn't start the engines in time", but as taxy time today was about 30 minutes it sems unlikely to have been the other favouites of no (centrally prepared and slower in the summer) figures or insecure cabin. Three of the four were orange. Okay, sometimes I can get someone past and not lose the runway capacity, but sometimes I can't. If I lose a movement it is unlikely to be made up until the end of the day. EVERY subsequent aircraft that day will experience a delay as a result. My customer (the airport) will not be best pleased by this because they can't plan on the runway utilisation otherwise possible, but surely all the subsequently delayed company aircraft also counteract any cost savings from this behaviour. Incidentally, the difference between being ready at an intersection when the opportunity exists to make use of your favourable SID and joining the back of the queue at the holding point could be 20 minutes. When aircraft are not ready when I need them to be I often log their delay and it usually makes more than 4-6 minutes difference.