Yet another images in tables question alignment. Want text to start at top of cell. Not centered

With the valign=t option (from the adjustbox package) you can achieve the desired layout also in a longtable environment:

\documentclass[12pt]{article}%
\usepackage{graphicx}
\usepackage{longtable}  
\usepackage[export]{adjustbox}  
\begin{document}        
\begin{longtable}{|p{1.5in}|p{3in}|p{1.5in}|}\hline 
AAAAAAAAAAAA AAAAAAAAA&
\vspace{0pt}\includegraphics[width=3in,valign=t]{example-image-a}&
BBBBBBBBBBB BBBB BBBBBBBBB BBBBBBBBB\\\hline 
AAAAAAAAAAAA AAAAAAAAA&
\vspace{0pt}\includegraphics[width=3in,valign=t]{example-image-a}&
BBBBBBBBBBB BBBBBB BBBBBBBBB BBBBBBB\\\hline 
\end{longtable}
\end{document}

as supplement to @leandris answer, with some off-topic suggestions (which can be helpful):

\documentclass[12pt]{article}%
\usepackage{longtable}
\usepackage[export]{adjustbox}  % it load graphicx too
\usepackage{etoolbox}           % for Gin's key patches

\begin{document}
    \begingroup
\expandafter\patchcmd\csname Gin@ii\endcsname   % needed etoolbox
    {\setkeys {Gin}{#1}}
    {\setkeys {Gin}
      {width=\dimexpr\linewidth-\tabcolsep,  % standard graphicx settings
       valign=t, margin=0pt 6pt 0pt 6pt}     % settings from adjustbox
    }{}{}
\begin{longtable}{|p{1.5in}|p{3in}|p{1.5in}|}
    \hline
AAAA AAA AA AAA AA AAAAA AA
    &   \includegraphics{example-image-a}
        &   BBBBBBBBBBB BBBB BBBBBBBBB BBBBBBBBB            \\
    \hline
AAAA AAA AA AAA AA AAAAA AA
    &   \includegraphics{example-image-b}
        &   BBBBBBBBBBB BBBB BBBBBBBBB BBBBBBBBB            \\
    \hline
AAAA AAA AA AAA AA AAAAA AA
    &   \includegraphics{example-image-c}
        &   BBBBBBBBBBB BBBB BBBBBBBBB BBBBBBBBB            \\
    \hline
\end{longtable}
    \endgroup
\end{document}

note: your table is wider than text width!