ATC: Fly heading 120photofly wrote: ↑Thu Mar 08, 2018 8:15 pmROGER means you received the entire transmission. If you know you didn't receive part of a transmission, don't say ROGER - because that would be the wrong thing to say. Instead, ask for the transmission to be repeated. In part, if you wish. ("SAY AGAIN ALL AFTER ..." and if you want, "WORDS TWICE".)
WILCO means you will comply with all the instructions. When would you ever comply with only part of an ATCO's instructions, without explicitly making clear which instructions you're unable to follow? And if for some reason you're not going to comply with all the instructions you received, don't say "WILCO". That would be wrong. Because WILCO doesn't mean "I will comply with part of your instructions." This is not difficult stuff.
I'm still not seeing any ambiguity.
Pilot: [thinking she heard "fly heading 210"] Wilco.
That's why we read back critical stuff when we're IFR.