Day fighter

A day fighter is a fighter aircraft equipped only to fight during the day. More specifically, it refers to a multi-purpose aircraft that does not include equipment for fighting at night (such as a radar and specialized avionics), although it is sometimes used to refer to some interceptors as well.

The term is an example of a retronym: before the development of effective dedicated night fighter aircraft early in World War II, in effect, all fighter aircraft that were not specifically modified for night combat were day fighters.

Examples of planes that were classified as day fighters were the Supermarine Spitfire and Messerschmitt Bf 109. Both were excellent interceptors, but were also found in roles such as fighter-bomber and reconnaissance. However, neither was really able to be used as a useful night fighter, so the term day fighter was used to describe designs of this sort. Other day fighters such as the Hawker Hurricane Mk.IIC and Fw 190 were also employed as night fighters after a fashion. Although they were marginally more successful than the Spitfire and Bf 109, the reason they were preferred in the night-fighting role is that they had wide-track landing gear, rather than the narrow track landing gear that made landing a Spitfire or Bf 109 so difficult, particularly in the dark. As far as actual night combat went, none of these aircraft were particularly successful compared to true night fighters. Some day fighters like the Grumman F6F, Vought F6U and Lockheed P-38 were converted into true night fighters with the addition of aerial radar tracking systems, with some success.

As aircraft grew more complex and capable, and as much equipment (such as radar systems) that are used for blind flying at night can also be used for flying in cloud and other adverse weather, the term "night fighter" has been largely dropped in favor of "all weather fighter", or "all weather aircraft", as the same technology applies to ground attack aircraft and bombers (with the exception of systems for tracking and destroying enemy aircraft in limited visibility). "All weather" simply implies that the aircraft is not reliant on clear weather or daylight to complete its mission, although they are not truly all weather aircraft; most are incapable of flying under severe weather conditions.

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Wikipedia