On the panel of and old aircraft (Caravelle), I saw the 'nav lights' switch had three positions: Off, Steady, Flashing,When and why were the nav lights required to be 'flashing'? (NB. it was nav light, not 'anti-collision' light).
Flashing is the position used on the ground for taxi. Steady is used for flight.
Not only that aircraft baut all kind of aircraf has it Nav light in 3 mod off-steady-flashing.
Very odd. I've flown a lot of different types of aircraft and I've never seen any exterior light that flashed other than anti-collision or, on occasion, landing lights (selectable on approach to be more noticable).
Many French aircraft were, and possibly, still are equipped with a flashing position for the navigation lights. The reason for this is the ICAO rules for interception. The intercepted aircraft is to turn on its navigation lights (at night, rock wings during day) and flash them at irregular intervals if trying to indicate I understand and will comply to the intercepting aircraft. They were to be left on until the intercepter gave another instruction. The flashing mechanism in the aircraft was designed to flash the nav lights in an irregular fashion. Apparently, the French got intercepted a lot in the middle east and over Russia. Other uses were for indicating an inoperable radio. Flashing navigation lights used to mean no radio communication in parts of Europe. In the U.S., it is also customary (at night) to flash your landing light or nav lights when your radio is inop and you are acknowledging the tower's light gun signal. I can't think of a reason to let them keep on flashing and have a special switch position for that.
The nav lights, also called position lights, are the lights on the tips of each wing. The left (port) light is always red, and the right (starboard) light is always green. (BTW ships also have position lights in this manner.) Some airplanes, especially large jets like the Caravelle, also have a white position light placed in the tail. The steady position of the switch simply illuminates all the position lights. When the switch is moved to flashing, it actually activates a second set of lights, called strobes. Strobes are usually found somewhere near the position lights on each wing. They are bright white bursts, and you want to keep them off while you're at the terminal and taxiing close to other aircraft. Most newer aircraft have a seperate strobe light switch, in addition to the nav light switch.
