As (they) scheduled, they met on February 16.

[sitifan]

Are the sentences below acceptable to native speakers?
(1) As scheduled, they met on February 16.
(2) As it had been scheduled, they met on February 16.
(3) As it was scheduled, they met on February 16.
(4) As they scheduled, they met on February 16.

 

[5jj]

Only #1 works for me.

 

[sitifan]

(5) As had been scheduled, they met on February 16.
(6) As was scheduled, they met on February 16.
Are the above sentences acceptable to native speakers?

 

[Barque]

5 sounds all right.
6 could work but the "was" seems unnecessary.

 

[Tarheel]

The meeting had been scheduled for February 16. Then, as scheduled, they met on that date.

There is no need to make it wordier.

 

[5jj]

The meeting had been scheduled for February 16. Then, as scheduled, they met on that date.

That's longer than those of sitifan.

 

[Tarheel]

That's longer than those of sitifan.

I was referring to:

As scheduled, they met on February 16.