1. INTRODUCTION

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 communication facilities.

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 will reply.

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 satisfactory communication:

(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.

e. Identifications

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.