It's impossible to do up-down from New York to London.

[Dharminder Singh]

Suppose I want to say that it is impossible to go to London from New York in the morning and then return back to New York before evening.

How would I say this?

"It's impossible to do up-down from New York to London in a day."

Is this sentence correct or is a better alternative to say this?

[Requests for answers from named members deleted by Rover_KE.]

 

[Piscean]

[Requests for answers from named members deleted by Rover_KE.]

Please stop directing your questions at individual members. All members who have something to contribute have a right to respond to posts.

 

[Rover_KE]

Suppose I want to say that it is impossible to go to London from New York in the morning and then return back to New York before evening.

Could I say this?

"It's impossible to do up-down from New York to London in a day." NO.

Is this sentence correct or is there a better way to say this?

The sentence is not correct. Your opening sentence is a better way of saying that. You could also say "It's impossible to make a return flight between New York and London in a day.

(Flying through multiple time-zones is one of my blind-spots, so somebody else can decide whether your opening statement is actually true.)

 

[Dharminder Singh]

Let's hypothetically consider that the time zone is the same.

Let's not — that makes it a pointless exercise.

If you want to do that, pick two cities in the same time zone.

 

[Dharminder Singh]

I just wanted an alternative because my opening statement is very lengthy. I want a shorter statement.

"It's impossible to make a return flight between New York and London in a day."

"It's impossible to fly from New York to London and back in a day."

 

[Piscean]

I just wanted alternative because my opening statement is very lengthy. I want a shorter statement.

It is impossible to go to London from New York in the morning and then return back to New York before evening.

Apart from removing the redundant 'back', that' fairly concise. You could consider:

You can't fly from New York to London and back in one day.