Wake separation behind a DA42?

London Control have been used timed separation for departures since before I became an air traffic controller in 1985. I suspect that there may have been a subtle change somewhere such that this has become more apparent at Shoreham/Goodwood.

I guess you are already satisfied with the explanation you have Peter, but for what it’s worth I have encountered this at many IFR class G airports.

Were you also routing to or near GWC?

The problem is that while they don’t need to worry about separating you in class G (aside from duty of care arguments), It is not much good for them if they have to have separation of xnm at the same altitude or yft, or a combination of xnm and yft for composite separation if you both get given a clearance (example only, I know not the procedures at Shoreham) to join CAS on track GWC climbing to FL90, because then chances are you are going to both enter controlled airspace already in a loss of separation scenario.

I have had this happen at Biggin fairly often were I have been waiting to depart with no real traffic around aside from a departure only to be told that “your clearance is on request with Thames, expect a 5 minute delay”

Emir, isn’t twin-envy great?

Yeah, I’m just smiling

Sorry, could not resist …

Only for fast twins :-)

SCNR

Emir, isn’t twin-envy great?

The reason they ask you to wait is because DA42s are so slow you would quickly catch up with your TB20…

Not a problem, after 1NM there will be 1000ft vertical separation with the TB20 on top

This also happens at my homebase (EHLE) when two aircraft are departing at the same time on a Z flightplan. The second aircraft will be assigned a 5 min. delay, when it receives the IFR clearance.

We also had it when flying back from Cambridge with 2 aircraft. Our friends in the second aircraft had to wait for us to be handed over to a Radar unit on the SID, before they got their takeoff clearance.

Definitely not for wake turbulence