The many references to Omega in your excellent discussions on Navigation and traffic control published in the January issue were particularly gratifying to one who has worked on Omega for the past decade. Especially memorable was Mr. Stringer's statement that ‘[Omega] satisfies the three R's—reliability, redundancy and range’ and Mr. Jones' observation ‘' [Omega] is already the most widely deployed ground-based navigation aid in the world by a very substantial margin’. However, many contributors used words such as ‘somewhat unreliable’ and ‘subject to real problems’ when discussing ambiguity resolution. Perhaps some further remarks on ambiguity resolution are in order.