ATP-5-0-2-1 Staff Reference Guide Volume 1 Download
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Command and Control Planning Factors 07 December 2020 ATP 5-0.2-1 317 EXPRESSING UNNAMED DATES AND HOURS I-19. Table I-7 details the operational day and hour concept. Table I-7. Designated letters for dates and times FM 6-0 Term Definition C-day The unnamed day on which a deployment operation commences or is to commence (JP 5- 0). The deployment may be movement of troops, cargo, weapon systems, or a combination of these elements, using any or all types of transport. The letter “C” is the only letter used to denote the activities described above. The highest command or headquarters responsible for coordinating planning specifies the exact meaning of C-day within the aforementioned definition. The command or headquarters directly responsible for the execution of the operation, if other than the one coordinating the planning, will do so in light of the meaning specified by the highest command or headquarters coordinating the planning. Ends at 2400Z. D-day The unnamed day on which a particular operation commences or is to commence (JP 3-02). E-day The day on which a NATO exercise commences or is due to commence (AAP-06). E-day (amphibious operations) The day landing force personnel, supplies, and equipment begin to embark aboard amphibious warfare or commercial ships (JP 3-02). G-day The day on which an order is or is due to be given to deploy a unit (AAP-06). H-hour The specific hour on D-day at which a particular operation commences (JP 5-0). H-hour (amphibious operations) In amphibious operations, the time the first landing craft or amphibious vehicle of the waterborne wave lands or is scheduled to land on the beach and, in some cases, the commencement of countermine breaching operations (JP 3-02). L-hour The specific hour on C-day at which a deployment operation commences or is to commence (JP 5-0). Normally established to allow C-day to be a 24-hour day. L-hour (amphibious operations) In amphibious operations, the time at which the first helicopter or tiltrotor aircraft of the airborne ship-to-shore movement wave touches down or is scheduled to touch down in a landing zone (JP 3-02). P-hour (airborne operations) An airborne operation begins at parachute-hour (P-hour), which is when the first paratrooper exits the first aircraft. Notes. • C- and D-days end at 2400 hours, Universal Time (ZULU time). For planning purposes, these days are 24-hours long. Refer to days preceding or following C- or D-day by using a plus or minus sign and an Arabic number after the letter. For example, D-3 is three days before D-day; D+7 is seven days after D-day. When using a time element other than days, spell it out: for example, D+3 months. • Refer to hours preceding or following H- or L-hour by a plus or minus sign and an Arabic number after the letter. For example, H-3 is three hours before H-hour; H+7 is seven hours after H-hour. When using a time element other than hours, spell it out: for example, H+30 minutes. • Where it is necessary to identify a particular operation or exercise, place a nickname or code words before the letter, such as BALD EAGLE (D-day) or ANVIL EXPRESS (C-day).