MS 9923 comprises papers collected by Charles Ulm as well as those collected by his son, John. The papers comprise newspaper cuttings, stamps, commemorative envelopes, correspondence, brochures, research notes, articles, reviews, certificates, talks, handwritten notes, photocopies of government records, business papers, photographs, maps and ephemera. The largest series in the collection is the commemorative and philatelic material, comprising stamps, commemorative envelopes, tribute albums, newspaper cuttings, articles and reviews relating to the 50th anniversary of the first trans-Pacific flight. The 1928 flight saw Charles Ulm fly with Charles Kingsford-Smith on the Southern Cross from Oakland, California to Brisbane, Australia (8 boxes, 1 fol. box).