VWP and Flight Training
Some of the members that have posted here seem to really know this topic well and by no means I am pretending here to make a significant contribution to this debate, but I just wanted to quote the ESTA website on this Warning message:
WARNING: If upon application for admission to the United States at a port of entry you are admitted under the Visa Waiver Program by a US Customs and Border Protection Officer, you may not accept unauthorized employment; or attend school; or represent the foreign information media during your visit under the program. You may not apply for: 1) a change of nonimmigrant status, 2) an extension of stay, or 3) adjustment of status to temporary or permanent resident, unless eligible under section 245(c)(4) of the Immigration and Nationality Act. Violation of these terms will subject you to REMOVAL.
For those of us that thought they could get additional ratings under VWP...