Like their German allies, the Japanese have emphasized
close coordination of land and air communications.
This was especially true in the Malaya and Philippine
campaigns, in which the Japanese enjoyed considerable
air success. The information below has been translated
freely from Japanese documents, and most of it deals
with air-ground communication.
2. INSTRUCTIONS FOR LAND-AIR LIAISON
Smooth land and air communications can be maintained only
by understanding thoroughly the details of both land and air
Anyone working with antiaircraft communications should be
able to identify both friendly and enemy aircraft, and should
have a knowledge of the principal characteristics of air tactics
and aircraft performance.
Ordinarily one, or a combination, of the following methods of
communication is used:
(a) To aircraft from a ground unit: radio signaling panel,
message tube (by pick-up), heliograph, flare, smoke signaling, etc.
(b) To the ground from aircraft: radio message tube, heliograph, flare, smoke
signal, carrier pigeon, etc.
(c) There may be circumstances when other methods are used.
In the case of aircraft: signaling by different movements of the
plane, or by dropping paper signals. In the case of ground
troops: signaling by different unit formations, by flags, or by
placing white panels on the ground to express characters in a
message. (Japanese soldiers frequently carry Rising Sun flags
for identification purposes.)
Signaling posts mainly use panel signaling methods (if
necessary, however, flares or smoke signals may be employed). Pick-up message
tubes may also be used if features of the terrain permit.
a. Selecting a Panel Signaling Post
(1) Choose a position from which it will be easy to establish
communication. The place selected should not reveal the location
of headquarters. It is preferable to establish the signaling post
at a separate location.
(2) Make it easy for friendly aircraft to identify a signaling
post, but difficult for the enemy.
(3) Select an area large enough for either message tubes or
panel signaling. The dropping point for message tubes depends
upon the direction of the flying plane, and the direction and velocity
of the wind. In any event, tubes should be dropped within
a radius of 100 yards from the center of the signaling post.
Avoid dropping tubes in villages, forests, tall grass, rivers, or swamps.
(4) The pick-up area should be open and flat, and should be
at least 300 feet wide by 1,500 feet long into the prevailing wind.
Surrounding areas should be free from obstructions to flying.
b. Dropping Message Tube From Aircraft
(1) Fly over the expected location of the panel signaling post. Give
a "call" signal and request a position for dropping.
(2) When the panel signaling post is located, fly low and drop a message
tube aimed at the panel.
(3) When message "Received message tube" is shown on panel
signaling post, depart. If the signal "Message tube not received" is
shown, repeat procedure.
c. Operating a Panel Signaling Post
Communication from a panel signaling post to an aircraft is
carried out as follows:
(1) Give the signals "requested" and "call."
(2) If the signal "understand" is received from an aircraft, give the
panel message immediately. When the message is completed, give
the signal "Message completed."
(3) Sometimes a message may be given without a call signal.
(4) Remove panels on receipt of "understand" signal from aircraft, or
when it is believed your message has been received. Repeat the
signal if "Repeat signal" is given.
Communication from aircraft to the panel signaling post is carried out as follows:
(1) When the call signal is given from the panel signaling post, reply
with the signal "understand," and wait for a panel signal.
(2) Give the signal "understand" if the panel signal is interpreted, but, if
not, give "Repeat the signal."
(3) The need for communication from an airplane to a ground
unit can be determined by giving the "call" signal from the aircraft, and
waiting for a reply from the panel signaling post.
In the event that an aircraft signals, the panel signaling post
The following precautions must be taken in panel signaling:
(1) Study the position of aircraft and facilitate observation from air.
(2) Make air observation as long as possible.
(3) If a panel is not seen from the air, leave the signal until
the observer can see it.
The following precautions have to be taken in order to maintain
(1) Lay a panel in the correct position and remove any big wrinkles.
(2) Remove any object which obscures the view of the panel from the air.
(3) When using smoke to draw the attention of an aircraft, do not
let smoke obscure the panel.
(4) Panels not in use will be disposed of in such a manner as to be
invisible from the air.
(5) Index number panels will be laid from the first figure and
down in order, and other panels will be laid or removed at the same time.
In order to speed up the finding of a dropped message tube, more
than two persons (pickers) will be posted about every 100 yards.
d. Pick-up Message Tube Method
(1) Panel signaling post.--Give the signal "pick-up a message
tube" and if the preparation is complete, give the signal "ready."
(2) Aircraft.--If the signal "pick-up a message tube" is
recognized, give the signal "understand."
Wait for a "ready" signal and pick up a message tube by flying low.
In addition to the Rising Sun on the wings, our planes can be
identified by a white line, approximately 8 inches wide, near the
tail end of the fuselage.
Friendly planes use the following signals to identify themselves
to ground forces:
(1) When a plane is alone, it will waggle its wings. In the
case of a formation, the plane at the extreme end will give this signal.
(2) When about to cooperate with land forces, the planes will
usually circle overhead.
(3) At night, the navigation lights are usually turned on and off.
(4) When aircraft other than fighter planes approach friendly
troops at night, our "shooting star" is fired if necessary.
3. MISCELLANEOUS ORDERS
In order to prevent leakage of information, all detachments
will use army telephones as much as possible when communicating
with each other.
In writing letters home, you will not give the following information: Name of
place, military strength, matters concerning our army, establishments, future
movements, or discussion of air raids.
You will be permitted to write the following: Am fighting south of the
equator, need more competition, the enemy is weak, am fighting
fiercely, and am living under conditions similar to those of the regular residents.
The division signal unit will install the communication net, and
must carry out the communication liaison with the reserve
unit, with both flank units, and with the command post.