B737-700
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 209
Other / Unknown
Ground Event / Encounter Object; Inflight Event / Encounter Object
General None Reported / Taken
Human Factors
While turning base leg for a Visual Approach to Runway 24R at LAX; I spotted a red or orange object pass closely over the top of my (Captain) windscreen. I saw the object for less than one second; and immediately thought it was a model UAV (4-legged cross looking). I reported this to SoCal Approach so they could pass advisories to proximate aircraft. It all happened so quickly that I can't be completely sure the object was a UAV; versus paper; balloons; etc. However; I do remember the object being square shaped with defined lines; versus irregular like paper or balloons. The object was definitely red or orange in color. I failed to report this sooner; because it happened so quickly; and we were involved in our approach; so after it happened; it completely slipped my mind.  This object was so small it could not be seen in time for evasion. If it was a UAV; it shouldn't be flown that high near a major airport.
B737-700 Captain reports sighting a small UAV at 4;000 feet during a visual approach to Runway 24R at LAX.