ATTP 5-0.1 Commander and Staff Officer Guide - Army Electronic ...

Chapter 12
EXPRESSING UNNAMED DATES AND HOURS
12-58. Use specific letters to designate unnamed dates and times in plans and orders. See Table 12-1.
Term Definition
Table 12-1. Designated letters for dates and times
C-day The unnamed day on which a deployment operation commences or is to commence. 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” will be the only one used to
denote the above. The highest command or headquarters responsible for coordinating the
planning will specify 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 (JP 1-02).
D-day The unnamed day on which a particular operation commences or is to commence (JP 3-02).
F-hour The effective time of announcement by the Secretary of Defense to the Military Departments
of a decision to mobilize Reserve units (JP 1-02).
H-hour The specific hour on D-day at which a particular operation commences (JP 1-02).
H-hour
(amphibious
operations)
P-hour
(airborne
operations)
For amphibious operations, the time the first assault elements are scheduled to touch down
on the beach, or a landing zone, and in some cases the commencement of countermine
breaching operations (JP 3-02).
In airborne assault operations, the specific hour on D-day at which a parachute assault
commences with the exit of the first Soldier from an aircraft over a designated drop zone.
P-hour may or may not coincide with H-hour (ATTP 5-0.1).
L-hour The specific hour on C-day at which a deployment operation commences or is to commence
(JP 1-02).
L-hour
(amphibious
operations)
In amphibious operations, the time at which the first helicopter of the helicopter-borne
assault wave touches down in the landing zone (JP 3-02).
M-day The term used to designate the unnamed day on which full mobilization commences or is
due to commence (JP 1-02).
N-day The unnamed day an active duty unit is notified for deployment or redeployment (JP 1-02).
R-day Redeployment day. The day on which redeployment of major combat, combat support, and
combat service support forces begins in an operation (JP 1-02).
S-day The day the President authorizes Selective Reserve callup (not more than 200,000)
(JP 1-02).
T-day The effective day coincident with Presidential declaration of national emergency and
authorization of partial mobilization (not more than 1,000,000 personnel exclusive of the
200,000 callup) (JP 1-02).
W-day Declared by the President, W-day is associated with an adversary decision to prepare for
war (unambiguous strategic warning) (JP 3-02.1).
12-59. C-, D-, and M-days end at 2400 hours, Universal Time (ZULU time). They are assumed to be
24-hours long for planning. Plans and orders state the letters used and their meanings. If a plan mentions
more than one event, refer to the secondary event in terms of the time of the primary event. Staffs refer to
days preceding or following C-, D-, or M-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, staffs spell it out. For example, D + 3 months.
12-60. Staffs 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, staffs spell it out. For example, H + 30 minutes.
12-61. Where it is necessary to identify a particular operation or exercise, staffs place a nickname or code
words before the letter, such as BALD EAGLE (D-day) or ANVIL EXPRESS (M-day).
12-8 ATTP 5-0.1 14 September 2011