In YDF they issue us a clearance while engines off with a "Not valid until ABC123 is down and clear or cancels IFR" statement. If i'm at another MF where a VFR departure isn't an option and the Radio Operator advises us that we'll have to wait til so and so lands or cancels before our clearance can be issued, can I request this same procedure?

It always seems that I'm trying to copy down a lengthy modified clearance with a HDG BPOC a new altitude with an expect higher time and a cancelled time all while in the backtrack and still having to do a checklist and make a 126.7 call.

Our SOP states that the taxi out should be a sterile cockpit. When I was issued the clearance in YDF I thought that it was a great way to improve CRM and situational awareness and reduce the line-up work load.

Is it acceptable to ask for this in the future at any MF?

I will use "do not depart until ABC is on or cancels IFR". If I am busy and you aren't going to get off before traffic and VFR dep isn't an option, I'll elect to not issue a clx and deal with something else somewhere else.

We use "CLEARANCE VALID AT (time)" or "CLEARANCE VALID WHEN (event)" when dealing with a tower. When issuing a clx through flight service we are to use "DO NOT DEPART UNTIL (time)" or "DO NOT DEPART UNTIL (event)".

Can you get it elsewhere? Sure. Depends on the controller. Some will use it, some won't. Of those that do use it, like me, sometimes conditions will dictate that we don't use it. As for requesting it, I'm not sure that you will have any luck if it isn't offered. When you ask radio for a clx, they call me. As I stated, I will either use it or not, depending on what I'm doing at the time. I can't imagine that asking radio after being told you'll have to wait will get you anywhere.

"Not valid until ABC123 is down and clear" is a bit odd. "Clear" isn't something we will issue. Must be a hold over from sometime in the past or radio is adding it (which they shouldn't be doing).