I've never seen an airline application or FAA form that asked about arrests. Convictions, yes, but not arrests. You are not hiding anything by not coming forward with them. If they ask, then yes you should give the details and be honest. But if they only ask about convictions (inculding pleas and deferred ajudication) then you are being completely honest when you say no.
on a somewhat related note. lets say you got a speeding ticket or two and you know a lawyer who took them to court and got them thrown out. technically you were found not guilty of those speeding tickets. so should you reveal them on an interview that you got them when asked?