It would be good if "the airline" could at least send in a word of compliment acknowledged/ thanks. From what I have read in forums, "it" responds to complaints very fast, but what about compliments? I sent in one a month ago and still no reply... till this day. On the contrary, even our public transport operators respond quicker (within 1 week)! Even a Qatar airline customer service officer was pleased to hear of my compliment when I called the Singapore office to speak of my nice experience with that airline.
Complaints help to remind an organisaton that something is wrong; but compliments serve to genuinely recognise the good service by the staff in the organisation too. If "that airline" can at least send in a letter of acknowledgement for a compliment, it would help the writer know that the staffs' effort is duly recognised.
But on the other hand... if compliments go unanswered, the passengers would be left thinking;
"Why should I waste the effort to write in when there is no appreciation by the company?"
Compliments and Complaints are equally important. Hope "that airline" can appreciate them both.