Gentlemen (and ladies) on this superb thread. I hope this question isn't too "spotterish" but I'm sure it can be answered here. I've learned sooooo much about this gorgeous aircraft reading these pages.
I was listening to this radio dialogue between the last Concorde to leave JFK on Youtube here:
YouTube - Last concorde communication with JFK.wmv
It's actually a very lovely (well to me it is) almost 7 minutes, with the very final sentences spoken each way - such a nice touch. Just being humble SLF though, I can't work out what "Mike" means in the dialogue i.e.
For the last time, Speedbird Concorde 2 IFR London Heathrow with Mike requesting a Canarsie climb.
Also
... expect FL290 10 minutes after, Squawk 1136 and Mike is the ####
What's Mike and also the #### term?
Thanks. CD