Will this Strategy work?

[rsgopi]

I understand a visitor will be in legal status upto 240 days after i-94 expiry as long as the extension application is pending. My Father-in-laws's I-94 expires on August 22. We want him to stay with us for one more month. Can the below strategy preserve his 10 year visa even if the extension get denied?

Lets say we apply for extension on Aug 15 and normally it takes USCIS atleast 2 months to process. So i may receive a decision around mid October. If my FIL leaves US on Sep 22nd he is still legal and his 10 year visa is valid even if the extension got denied, right (as at the time of the denial notice he is not in the country!)

[rsgopi]

In other words, If the visitors leave before the approval/denial letter is mailed are they still in status? (even if the extension gets denied)

[kabkaba]

Unfortunately that is not correct. If extension is denied, illegal stay is counted from I-94 date and if that is past, Visa is void.