For example, what happens if you miss your wheels up time? On FlightRadar24 and LiveATC, I was following an Emirates A380 taxying to runway 23 at CYYZ for takeoff when a Jazz Embraer 175 came up behind it and was directed to a parallel taxiway so that it could go ahead of the A380 in order to meet its wheels up time.

Estimated Departure Clearance Time (EDCT) is essentially the time slot that an aircraft must depart from an airport in order to arrive at the destination airport at a specific time.

This is also called a "wheels up time" and is when the FAA expects to give takeoff clearance. Aircraft have 5 minutes on either side of their EDCT to depart or they will be assigned a new EDCT and expect further delays. When conditions improve, or when demand decreases, the ATCSCC begins running compressions.

It's all to keep traffic flowing in a steady manner.  If your "Wheels up time" is missed, then a new one is assigned.

12 minutes ago, charliearon said:

Aircraft have 5 minutes on either side of their EDCT to depart or they will be assigned a new EDCT and expect further delays.

There was another occasion where the A380 was almost at the runway when the F/O said they were checking something and it would take about 30 more seconds. Tower cleared them to line up but they ended up taking a lot more than 30 seconds and holding up about half a dozen other aircraft. They ended up leaving the runway, circling round and rejoining the lineup. So that must have all happened within the EDCT plus or minus 5 minutes.

 

21 minutes ago, charliearon said:

the ATCSCC begins running compressions.

What does that mean? The only compressions i know are in CPR.

35 minutes ago, dmwalker said:

What does that mean? The only compressions i know are in CPR.

Beats the 💩 out of me!