To add to what the other answers have given, the earliest reference to airships I can find was a 1E AD&D-era Dragon Magazine article on the Halruaan Airships by Ed Greenwood, the creator of the Forgotten Realms. The article is “Sailors on the Sea of Air” from Dragon #124 (August 1987), pp. 18–20.
As with many of Greenwood's early Dragon articles, the article takes the form of a description based on fictional letters received by Greenwood from a Forgotten Realms character (in this case the sorceress Laeral) that describes the Halruaan Airships. Because of this fictionalized format, the article is short on mechanics, though it does give the ships' flight ceiling as 3,600 feet, meaning they must wend their way through high mountains. It also describes a magical rod with which the captain controls altitude, one that needs "continual recharging."