The first sustained flight.
Letters of Note reprints the telegram the Wright Brothers sent to their father, who was a Bishop of the Church of the United Brethren in Christ, in 1903, after getting their Flyer to successfully make four sustained trips. The transcript:
“176 C KA C8 33 Paid. Via Norfolk Va
Kitty Hawk N C Dec 17
7 Hawthorne St
Success four flights thursday morning all against twenty one mile wind started from Level with engine power alone average speed through air thirty one miles longest 57 seconds inform Press home Christmas.
Orevelle Wright 525P”