I have an 11:55 flight to New York out of Heathrow Terminal 3 on
Tuesday. How much time should I give myself to get there, considering
the planned shutdown of the Piccadilly line west of Hatton Cross?

I will have luggage, although I should be able to carry it up the 33
steps at Hatton Cross with some difficulty. I'm still worried about
time. Do the buses tend to be overcrowded or should I be able to fit
on the first one that pulls up? And do they tend to get stuck in
traffic? The posters in stations advise passengers to allow an extra
20 minutes; is that realistic? Exactly where in the train should I be
to be closest to the exit at Hatton Cross? (No, I don't have the Way
Out book.)

Somebody suggested the 111 bus from Hounslow East instead. That will
avoid the steps and probably the crowds, but from what I can see, the
111 takes a while to reach the airport. Having already missed a flight
last year out of LCY due to a bus that took just a wee bit longer than
I had expected, I think I'll pass.

I'd rather avoid Heathrow Express and Heathrow Connect. (Why aren't
Underground tickets, including Oyster, valid on HE and HC during these
outages?)

Also, for anybody who's flown out of Heathrow lately -- should I be
aiming to be at the airport about three hours before the flight or is
that overkill?

And why is this outage taking place in the middle of the week
(immediately following a holiday weekend, yet!) in the first place? At
first I thought it was necessary to allow the line to Terminal 4 to
reopen on 1 September. But according to the latest batch of posters,
the line to Terminal 4 isn't reopening until later in the month!