Get Isset Variable to Specific Value

if (isset($data['start']['tan']) AND $data['start']['tan'] == true) {
    $get_data[] = 'tan';
}

if (isset($data['start']['ban']) AND $data['start']['ban'] == true) {
    $get_data[] = 'ban';
}

if (isset($data['start']['pan']) AND $data['start']['pan'] == true) {
    $get_data[] = 'pan';
}

Try to take only tan equal to "a111" values. Tested the code below, but I could not get even tan values.

if (isset($data['start']['tan']) AND $data['start']['tan'] == true AND $data['start']['tan'] == 'a111') {
    $get_data[] = 'tan';
}