Recuperar Checkbox

Pessoal, estou recuperando os dados gravados no BD (MySQL) para poder editá-los, todos os campos estão retornando os valores certinhos, porém não consigo recuperar os checkbox que foram marcados. Alguém pode me dar essa forcinha?

Segue abaixo o código da minha página:

<?php

include "sql.php";
if(isset($_POST['done'])){

 $id = $_POST['id'];
 $nome = $_POST['nome'];
$data_cadastro = $_POST['data_cadastro'];
$n_cadastro = $_POST['n_cadastro'];
$rg = $_POST['rg'];
$cpf = $_POST['cpf'];
$data_niver = $_POST['data_niver'];
$endereco = $_POST['endereco'];
$n = $_POST['n'];
$bairro = $_POST['bairro'];
$cidade = $_POST['cidade'];
$cep = $_POST['cep'];
$telefone = $_POST['telefone'];
$celular = $_POST['celular'];
$email = $_POST['email'];
$bra = $_POST['bra'];
$situacao = $_POST['situacao'];
$obs = $_POST['obs'];
$aero = $_POST['aero'];

 $sql = mysql_query("UPDATE tbl_cadastro SET nome='$nome', data_cadastro='$data_cadastro', n_cadastro='$n_cadastro', rg='$rg', cpf='$cpf', data_niver='$data_niver', endereco='$endereco', n='$n', bairro='$bairro', cidade='$cidade', cep='$cep', telefone='$telefone', celular='$celular', email='$email', bra='$bra', situacao='$situacao', obs='$obs', aero='$aero' WHERE id='$id'")or die(mysql_error());
 $linha = mysql_affected_rows();
 if($linha == 1){
 $erro = "Dados alterados com sucesso!";
 } else{
 $erro = "Não foi possivel alterar os dados";
 }
}
$id = $_GET['id'];
$sql = mysql_query("SELECT * FROM tbl_cadastro WHERE id = '$id'");
$nome = @mysql_result($sql, 0, "nome");
$data_cadastro = @mysql_result($sql, 0, "data_cadastro");
$n_cadastro = @mysql_result($sql, 0, "n_cadastro");
$rg = @mysql_result($sql, 0, "rg");
$cpf = @mysql_result($sql, 0, "cpf");
$data_niver = @mysql_result($sql, 0, "data_niver");
$endereco = @mysql_result($sql, 0, "endereco");
$n = @mysql_result($sql, 0, "n");
$bairro = @mysql_result($sql, 0, "bairro");
$cidade = @mysql_result($sql, 0, "cidade");
$cep = @mysql_result($sql, 0, "cep");
$telefone = @mysql_result($sql, 0, "telefone");
$celular = @mysql_result($sql, 0, "celular");
$email = @mysql_result($sql, 0, "email");
$bra = @mysql_result($sql, 0, "bra");
$situacao = @mysql_result($sql, 0, "situacao");
$obs = @mysql_result($sql, 0, "obs");
$aero = @mysql_result($sql, 0, "aero");

?>

<style type="text/css">
.campo{
width:400px;
}

.style2 {font-family: verdana} .style8 {font-size: 12px} .style9 {font-size: 11px}

</style>
<form name="form1" action="atualagenda.php" method="POST" style="padding-top:40px;">
<?php

if(isset($erro)){

 print '<div style="width:80%; background:#ff6600; color:#fff; padding: 5px 0px 5px 0px; text-align:center; margin: 0 auto;">'.$erro.'</div>';
}
?>
<table border="0" width="80%" bgcolor="#f0f0f0" style="border:1px solid #ccc; margin:0 auto; position:relative;">
<thead>
<tr>
<th colspan="2">.:: Atualizar Ficha de Cadastro ::.</th>
</tr>
<tr>
 <td width="14%"><span class="style8 style2"><strong><strong>Data do Cadastro</strong></strong></span></td>
 <td width="86%" class="style9 style2 style9">
 <label>
 <input name="data_cadastro" type="text" id="data_cadastro" value="<?php echo $data_cadastro; ?>" size="15" maxlength="10" />
 <em>(Ex.: 00/00/0000)</em></label>
 </td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Nº Cadastro</strong></strong></span></td>
 <td><input name="n_cadastro" type="text" class="style2 style9" id="n_cadastro" value="<?php echo $n_cadastro; ?>" size="16" maxlength="16" /></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Nome</strong></strong></span></td>
 <td><span class="style9 style2 style9">
 <label>
 <input name="nome" type="text" id="nome" value="<?php echo $nome; ?>" size="70" maxlength="70" />
 </label>
 </span></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>RG</strong></strong></span></td>
 <td class="style9 style2 style9">
 <input name="rg" type="text" id="rg" value="<?php echo $rg; ?>" size="18" maxlength="18" />
 <em>(Ex.: 00.000.000-0)</em></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>CPF</strong></strong></span></td>
 <td class="style9 style2 style9">
 <input name="cpf" type="text" id="cpf" value="<?php echo $cpf; ?>" size="18" maxlength="18" />
 <em>(Ex.: 000.000.000-00)</em></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Data de Aniversário</strong></strong></span></td>
 <td class="style9 style2 style9">
 <label>
 <input name="data_niver" type="text" id="data_niver" value="<?php echo $data_niver; ?>" size="15" maxlength="10" />
 <em>(Ex.: 00/00/0000)</em></label>
 </td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Endereço</strong></strong></span></td>
 <td><span class="style9 style2 style9">
 <label>
 <input name="endereco" type="text" id="endereco" value="<?php echo $endereco; ?>" size="90" maxlength="90" />
 </label>
 </span></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>N</strong></strong></span></td>
 <td><span class="style9 style2 style9">
 <label>
 <input name="n" type="text" id="n" value="<?php echo $n; ?>" size="10" maxlength="10" />
 </label>
 </span></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Bairro</strong></strong></span></td>
 <td><span class="style9 style2 style9">
 <label>
 <input name="bairro" type="text" id="bairro" value="<?php echo $bairro; ?>" size="40" maxlength="40" />
 </label>
 </span></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Cidade</strong></strong></span></td>
 <td><span class="style9 style2 style9">
 <label>
 <input name="cidade" type="text" id="cidade" value="<?php echo $cidade; ?>" size="35" maxlength="35" />
 </label>
 </span></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>CEP</strong></strong></span></td>
 <td class="style9 style2 style9">
 <label>
 <input name="cep" type="text" id="cep" value="<?php echo $cep; ?>" size="10" maxlength="10" />
 <em>(Ex.: 000000-000)</em></label> </td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Telefone</strong></strong></span></td>
 <td class="style9 style2 style9">
 <label>
 <input name="telefone" type="text" id="telefone" value="<?php echo $telefone; ?>" size="15" maxlength="15" />
 <em>(Ex.: (00) 0000-0000)</em></label>
 </td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Celular</strong></strong></span></td>
 <td class="style9 style2 style9">
 <input name="celular" type="text" id="celular" value="<?php echo $celular; ?>" size="15" maxlength="15" />
 <em>(Ex.: (00) 0000-0000)</em></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>E-Mail</strong></strong></span></td>
 <td><span class="style9 style2 style9">
 <label>
 <input name="email" type="text" id="email" value="<?php echo $email; ?>" size="85" maxlength="85" />
 </label>
 </span></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>BRA</strong></strong></span></td>
 <td><input name="bra" type="text" class="style2 style9" id="bra" value="<?php echo $bra; ?>" size="35" maxlength="35" /></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Modalidades</strong></strong></span></td>
 <td><span class="style9 style2 style9">
 <label> <strong>
 <input name="aero" type="checkbox" id="aero" value="<?php echo $aero; ?>" />
 Aeromodelismo
 <input name="heli" type="checkbox" id="heli" value="on" />
 Helimodelismo
 <input name="vcc" type="checkbox" id="vcc" value="on" />
 V.C.C.
 <input name="auto" type="checkbox" id="auto" value="on" />
 Automodelismo</strong></label>
 </span></td>
</tr>
<tr>
 <td><span class="style8 style2"><strong><strong>Situação Financeira</strong></strong></span></td>
 <td><input name="situacao" type="text" class="style2 style9" id="situacao" value="<?php echo $situacao; ?>" size="90" maxlength="90" /></td>
</tr>
<tr>
 <td><p class="style2 style8"><strong>Observações</strong></p>
 <p class="style2 style8"> </p>
 <p class="style2 style8"> </p>
 <p class="style2 style8"> </p>
 <p class="style2 style8"> </p></td>
 <td><span class="style2 style9">
 <label>
 <textarea name="obs" id="obs" cols="90" rows="10"><?php echo $obs; ?></textarea>
 </label>
 </span></td>
</tr>
</thead>
<tbody>
<tr>
 <td colspan="2"> </td>
 </tr>
<tr>
<td></td>
<td><input type="submit" value="Atualizar Cadastro" />
 <input type="button" name="button" id="button" onclick="javascript:location.href='edicao.php';" value="Cancelar" />
 <input type="button" name="button" id="button" onclick="javascript:location.href='edicao.php';" value="Voltar" />
 <input type="hidden" name="done" value="" /><input name="id" type="hidden" value="<?php echo $id; ?>" /></td>
</tr>
</tbody>
</table>
</form>

Obrigado pessoal!

<?php $check = (!empty($aero)) ? 'checked="checked"' : ''; ?>
<input name="aero" type="checkbox" id="aero" <?php echo $check; ?> />

<input type="checkbox" name="recordaudio" value="1" <?php echo $recordaudio;?> >

<form name="form1" action="<?php $_SERVER['REQUEST_URI']; ?>" method="post">

<div>
<a href="print.php?id=<?php echo $_POST["idlist"]; ?>" target="_blank" title="Visualizar">

<img src="btn/btnvis.png" width="88" height="24" alt="" border="0" />

</a>
</div>

<input onclick="contador(this);" type="checkbox" name="idlist[]" id="idlist<?php echo $cont;?>" value="<?php echo $lin['id']; ?>" />