The photo above, taken on 6 April 1925, shows a movie projector being loaded into an Imperial Airways aeroplane for the first in-flight movie ever. And the photo below shows the screen and interior setup for this historical feat. But was it really the first in-flight film ever shown? Technically, no.
Indeed is was one of the first, and amazingly those Imperial Airways flights even experimented with sound delivered via radio and a live orchestra. But if they weren't the first to play a movie in the sky, as they proudly claimed with that banner on the side of the plane, then who was? The answer is probably a flight in 1921 showing a short film called "Howdy Chicago!"
The "Howdy Chicago!" flights were happening during a trade show called Chicago's Pageant of Progress, and the film itself was more or less just an ad for how great Chicago was. We can compare and contrast that with the Imperial Airways flights four years later in any number of ways.
Imperial was screening The Lost World, a major Hollywood movie adapted from Arthur Conan Doyle's 1912 novel. The Chicago flights were showing a short film made by Chicago business boosters. So, yes, the Imperial flights were closer to what we think of today as in-flight entertainment. But the Chicago flights were the first known demonstrations of movies in an aeroplane.
The image below (clearly a photo-illustration, since the screen itself wouldn't have photographed that well) appeared in the August 22, 1921 issue of Aerial Age magazine and showed what the "Howdy Chicago!" screening might have looked like.
From the 22 August 1921 issue of Aerial Age magazine:
Motion pictures on the screen while flying through the clouds at 90 miles an hour! History's first aerial movie show was on board the eleven-passenger hydroplane, Santa Maria, at the Chicago Pageant of Progress -- and the first picture ever to be projected 2,000 feet above the earths surface was 'Howdy Chicago!" produced by the Rothacker Film Co. for the Chicago Boosters Club, for use in telling the world about the Windy City's selling points. A screen was hung in the forecabin of the machine; a DeVry suit-case projection machine fastened firmly in position and connected with an electric light socket. The projectionist pressed the button and the audience beheld cinema views of Chicago while flying over Chicago,
Before the flight it was feared that the vibration of the giant hydroplane as it shot through at 90 miles an hour would seriously interfere with the screening. But it did not. This historic flight demonstrated the practicability of movie entertainment for transatlantic aerial commuters in the days to come.
Anytime you're dealing with claims of technological "firsts" you're stepping into a steaming river of shit. Technically, the Imperial Airways flights were the first Hollywood feature movies shown on commercial flights. But the pedantic weirdos out there (read: me) can always say, "yes, but what about..." any time there's some technology or demonstration that was close and happened earlier.
You see this all the time with claims of "first" to technology -- like how today's brutal patent battles between companies like Apple and Samsung try to lay claim over the invention of glowing rectangles. And things only get more complicated as years pass and new high-tech becomes ancient history.
There may even be some example of a short movie being shown in an aeroplane prior to the 1921 Chicago experiments. If you know of any, please provide photos and links below, you pedantic jerks.
Pictures: A projector being loaded aboard a plane for the "first flying cinema trip" on 6 April 1925 and an interior shot of the film projector screen both via Getty Images; Photo illustration of the Chicago in-flight movie via Aerial Age magazine