14:9 is a compromise aspect ratio used to create an acceptable picture on both 4:3 and 16:9 televisions, conceived following audience tests conducted by the BBC. It is used by most UK, Australian and Irish terrestrial networks, and can be often seen on satellite at BBC World. Note that 14:9 is not a shooting format; 14:9 material is almost always shot on either a 16:9 or 4:3 format.
The major benefit in shooting 16:9 with protection for 14:9 (rather than 4:3), is improving the usable screen real-estate for titles, logos and scrolling text. The visible enhancement is significant due to the restrictive requirements of overscan.
A less common use is for material shot on a 4:3 format. When broadcast in 16:9, the top and bottom of the original frame are cropped to 14:9, and black bars are added to either side. When broadcast in 4:3, the 14:9 crop is often used in preference to the original 4:3 frame. This is especially common when 4:3 footage needs to be included in an otherwise 16:9 program, such as a news broadcast.
When shooting in 16:9 for potential 4:3 distribution the "Shoot And Protect" method (from the BBC's "Widescreen Book") is employed. As the name suggests footage is shot in 16:9 but important visual information is protected inside the 14:9 or 4:3 safe areas.