In preparation for the forthcoming offensive, GHQ today issued Contact Air Patrol instructions for the first time. These have been devised in light of RFC experiments in earlier battles and the experience of the French. The instructions are as follows:
“A certain number of aeroplanes, bearing distinctive markings should be detailed to carry out tactlcal observation of the battlefield having no other duties and reporting to the headquarters of the formation by which they were detailed, usually the Army Corps. The machines are ordered to fly low above and in the rear of our own lines, tO receive signals:
From assaulting Infantry by means of a. flares, b. the flashing of mirrors (vigillant periscope) with both of which officers and NCOs, and a proportion of other ranks of the infantry would be provided.
These signals might be given by the infantry.
a. On the initiative of company, platoon and section commanders when it was desired to make their positions known
b. On the signal from their aeroplane ‘where are you’?
c. At certain definite hours previously arranged in orders
d. On reaching a previously arranged position.
2. From Battalion and Brigade Headquarters by means of ground signals or lamps. Battalion and Brigade Headquarters which are to be marked by a ground signal, and units are to be provided with a ground signalling sheet or panel and a lamp.
EXPERIENCE IN BATTLE
The aeroplane is to answer by lamp and in both cases the Morse code is to be used. In addition to transmitting information or requests received from the infantry, the aeroplane detailed for tactical reconnaissance 15 to carry out continuous observation of the front of the formation and to keep the Command informed as regards:
a. During preliminary bombardment – any movement of the enemy.
b. During the attack – Progress of the attack and positions reached and the movements of reserves and impending counter attack.
The information received by the aeroplane from the infantry is to be transmitted at the outset by wireless and dropping messages. Messages dropped, however, will allow of fuller information being given than could be sent by wireless and this method is to be adopted whenever possible. As in the case of the French, the position reached by the infantry including Battalion and Brigade HQs is to be indicated by the observer on tracings prepared beforehand and dropped with the message.
A signal code was laid down for communication between infantry, Headquarters and the aircraft observer and various ground signals were devised. Eg., the aerial observer might show a white very light which asked, ‘Where are you?’ There were also ground signalling panels that consisted of large Louvre shutters painted flute on one side and a neutral tint on the other. These were connected by tapes and arranged horizontally on the ground in such a manner that of the shutter being activated by the tapes the white side was exposed uppermost for periods according to the Morse code, which could easily be observed from an aircraft between 5 and 6000ft.”