<p>WASHINGTON (AP) -- More than half the explosive-detection machines now at airports are not being fully used to screen checked baggage, even as the government plans to buy hundreds more of the minivan-sized equipment, the Transportation Department said Thursday.</p>
<p>Inspector General Kenneth Mead said the machines should screen at least 1,250 bags a day, but only 12 of 138 machines are reaching that level. Transportation Security Administration head John Magaw acknowledged the problem and said it would be fixed as trained federal baggage screeners replace private employees.</p>