You can only use php to "post" process the input. In otherwords, use the strtoupper() on the input field value ('depart') on the form action page. PHP is totally done with the page by the time the client (browser) sees the output.
If you need to force uppercase before the user submits the form then, you will have to use client side scripting (VBScript, JavaScript) to act on the input field.
BTW, to comply with XHTML standards, ALL attributes in a tag should be enclosed in double quotes and ALL tags must have 'ends':
<input type="text" name="depart" size="15" maxlength="25" value="K" style="font-family: Arial; font-size: 8pt" />