Q1: Does the fitness-for-duty affirmation that the PIC signed prior to when he found out about the delay serve as concurrence to an extension?

Subsection 117.l9(a) allows an FDP to be extended up to 2 hours beyond the pertinent FDP limit in response to unforeseen operational circumstances that arise prior to takeoff. This extension is subject to a number of limitations, one of which is that the PIC and the
certificate holder must both concur with the extension.' A document that the PIC signed before he found out about the need for an extension would not be sufficient to concur with the extension because a person cannot concur with something that he or she does not know about. Instead, the PIC must affirmatively concur with the extension.

So we sign the FDRA and agree to an extension that's known prior to signing. But if a reason materializes after signing (after block-out), we have to agree via ACARS. Correct?