I don't know which a/c Denti is talking about, but the 737 has two selectable 'low fuel' levels, one for ETOPS and one for non-ETOPS. Some airlines do not bother to distinguish between the two, so you can get the 'Amber' figures when you are not actually short and you do not need to do the 'low fuel check-list'. It is just a matter of education. On the 737 the check-list is only really required with less than 453kg in a tank but some airlines have it set at 906kg.