What is the pattern of the flashing light in Airbus A340-300?
For the lights on the A340-200/-300 see Documentation page 129.

For the lights on the A340-500/-600 see Documentation page 133.

Use the following link to see the lighting regulations for commercial aircraft -  http://www.whelen.com/pb/Aviation/System%20Requirements/Anit-Collision%20Systems.pdf

Use of lights

AIM 4−3−23. Use of Aircraft Lights was updated in the latest edition.

Guidance about using aircraft lights during ground operations also appears in AC91-73B, “Part 91 and Part 135 Single-Pilot Procedures during Taxi Operations.”

h. Use of Exterior Aircraft Lights to Make Aircraft More Conspicuous.

(1) General. Exterior aircraft lights may be used to make an aircraft operating on the airport surface more conspicuous. Pilots may use various combinations of exterior lights to convey their location and intent to other pilots. Certain exterior lights may also be used in various combinations to signal whether the aircraft is on a taxiway or on a runway, in position on the runway but holding for takeoff clearance, crossing an active runway, or moving down the runway for takeoff.

NOTE: Because adherence to the guidelines in this AC are voluntary and aircraft equipment varies, pilots are cautioned not to rely solely on the status of an aircraft’s lights to determine the intentions of the pilot(s) of the other aircraft. Additionally, pilots must remember to comply with operating limitations on the aircraft’s lighting systems.  

(2) Because adherence to the guidelines in this AC are voluntary and aircraft equipment varies, pilots are cautioned not to rely solely on the status of an aircraft’s lights to determine the intentions of the pilot(s) of the other aircraft. Additionally, pilots must remember to comply with operating limitations on the aircraft’s lighting systems.

(2) Exterior Lights. To the extent possible and consistent with aircraft equipage, operating limitations, and pilot procedures, pilots should illuminate exterior lights as follows:

(a) Engines Running. Turn on the rotating beacon whenever an engine is running.

(b) Taxiing. Prior to commencing taxi, turn on navigation, position, anti-collision, and logo lights, if available. To signal intent to other pilots, consider turning on the taxi light when the aircraft is moving or intending to move on the ground, and turning it off when stopped, yielding, or as a consideration to other pilots or ground personnel. Strobe lights should not be illuminated during taxi if they will adversely affect the vision of other pilots or ground personnel.

(c) Crossing a Runway. All exterior lights should be illuminated when crossing a runway.
CAUTION: Pilots should consider any adverse effects to safety that illuminating the forward facing lights will have on the vision of other pilots or ground personnel during runway crossings.

(d) Entering the Departure Runway for Takeoff or LUAW. When entering a runway after being cleared for takeoff, or when taxiing into position and hold, pilots should make their aircraft more conspicuous to aircraft on final behind them and to ATC by turning on lights (except landing lights) that highlight the aircraft’s silhouette. Strobe lights should not be illuminated if they will adversely affect the vision of other pilots.

(e) At Night, and When Cleared to LUAW. Consider lining up slightly (approximately 3 feet) to the left or right of the centerline (CL) to enable a landing aircraft to visually differentiate your aircraft from the runway lights.

(f) Takeoff. Landing lights should be turned on when takeoff clearance is received, or when commencing takeoff roll at an airport without an operating control tower.