Recognition: Army Air Forces Ground Observer Corps - Identification of Aircraft - I: The A. A. F. Ground Observer Corps

CHAPTER I: THE A. A. F. GROUND OBSERVER CORPS

SECTION I:  THE GROUND OBSERVER CORPS AND AIR DEFENSE

1. The A. A. F. Ground Observer Corps is an essential part of air defense.

2. Air Defense is the direct defense against enemy air operations. Counter-air-force operations, including reconnaissance and bombing of enemy airdromes and operations of ground and naval forces to deny air bases to the enemy, are not included within the scope of air defense.

3. Air defense may be divided into active air defense and passive air defense. Active air defense is the organization and the action designed to destroy enemy planes and their crews within a predetermined air space. Passive air defense is the organization and the action taken to minimize the effects of enemy air action.

4. Active air defense is conducted by means of fighter (interceptor pursuit) aircraft, antiaircraft artillery, the aircraft warning service necessary to the proper use of fighter units and antiaircraft, search-lights, and barrage balloons.

5. Passive air defense measures include dispersion, camouflage, blackouts, and all other measures of air raid precautions.

6. The Ground Observer Corps is a branch of the aircraft warning service. The volunteer civilian observers who staff the Ground Observer Corps are appointees of the Fighter Command of the Army Air Forces reporting directly to the Army and under Army supervision. Their function is an essential part of active air defense—the destruction of enemy planes and their crews.

SECTION II - THE GROUND OBSERVER CORPS IN OPERATION

7. The Ground Observer Corps operates a number of observation posts strategically located at points from which watch for aircraft can be effectively maintained. In active operation these posts are manned twenty-four hours a day by two or more observers.

8. When observers see or hear an airplane, they report certain information in a prescribed form immediately by telephone, direct to the plotter at the Army Filter Center board.

9. The plotter displays this information on the filter board. It is checked against similar reports of the same flight telephoned in by other observers, inaccuracies are discovered and corrected, and a track for the flight is established. Representatives of the Army, Navy and Civil Aeronautics Authority are asked to identify the flight as be-longing to one of their respective organizations by checking the description of the plane or planes, and the track of the flight, against flight plans which have been previously filed and approved. If they are unable to identify the flight, it is assumed to be enemy and so indicated on the plotting board.

10. Information which appears on the filter board is "told" to the plotters at the Information Center and displayed on the operations board.

11. The Controller or Air Defense Wing Commander sits in a balcony overlooking the operations board and bases his tactical decisions upon the information displayed thereon. When an enemy track appears on the operations board, lie knows front the information displayed there how many planes there are in the raid, what type of planes they are, how high they are, how fast they are moving, what direction they are heading in, where they are located, and what their possible objectives are. From this information, he can determine how many planes to use in interception and from what base they should be dispatched, what communities to warn of an impending raid, and what commands to issue to antiaircraft artillery.

12. Most important of all, the information on the board permits the intercept officer to determine the theoretical point in the air space which is being defended at which an interception should be made. Connected by radio telephone to the pilots who are effecting the interception, the intercept officer tells them in what direction to fly. at what speed and at what rate of climb. By charting the course of the enemy raid and that of the fighter planes he is directing, the intercept officer brings the fighters to a point where they should be within sight of the enemy. From there on, it's up to the fighter pilot to complete his mission.

13. The reports from the Ground Observer Corps, therefore, in last analysis, combined with information from other means of air-craft detection, actually fly the fighter aircraft to within sight of the enemy.

SECTION III - IMPORTANCE OF GROUND OBSERVER CORPS

14. The method of interception described above is known as the "ground alert method." In it, fighter aircraft are retained on an alert status on the airdrome until information is received of the approach of an enemy raid, when they are ordered off and directed to a point of interception.

'There are two other methods of fighter aircraft operation, known respectively as the "air alert method" and the "search patrol method."

16. The air alert method requires the maintenance of a fighter unit in the air, in a restricted locality, at all times during which the enemy may approach. Upon receipt of information of the approach of enemy aircraft, the fighter unit in flight is directed outward by radio to intercept the enemy. Some form of limited aircraft warning service is a prerequisite to the use of the air alert method. Aside from the operational expense of maintaining a portion of available tighter units in the air at all times, the air alert method requires at least four times as many planes as the ground alert method to provide an equal defensive value. It is employed only when the outer limit to which the aircraft warning service can be extended will not permit the employment of the ground alert method.

17. The search patrol method involves the continual search for the enemy by fighter aircraft in flight. It is resorted to only in exceptional circumstances when air superiority is required in a limited air space for a limited time, and an adequate aircraft warning service cannot be made available. British fighters at Dunkirk were forced to resort to the search patrol method. It is estimated that the search patrol method requires thirty times as many planes as the ground alert method to provide an equal defensive value.

18. A comparison of the above three methods of fighter aircraft operation and the part the Ground Observer Corps plays in the ground alert method provides an accurate estimate of the value of the Ground Observer Corps in air defense.

19. The plan developed by the Fighter Command for the air defense of the continental United States is predicated upon the efficient operation of a Ground Observer Corps. The percentage of successful interceptions of enemy bombers will depend to a considerable degree upon the timeliness and the accuracy of information reported by ground observers.

20. The duties of the ground observer are often inconvenient, some-times physically uncomfortable, almost never glamorous. No man or woman should volunteer for service as a ground observer looking for an easy job or with the intention of making anything other than an all-out effort to perform his or her duties efficiently and on schedule. The Ground Observer Corps is a part of the Army Air Forces and its personnel is expected to govern itself accordingly.

SECTION IV: REPORTING IDENTIFICATION OF PLANES

21. Since an unidentified plane is assumed by the Fighter Command to be of enemy origin, it is obviously of the utmost importance that each plane reported by an observation post be properly identified at the Information Center. Sometimes this is easy, as in the case of a regularly scheduled civilian transport which passes over a given point, headed in a given direction at the same hour every day. Sometimes, however, particularly if the pilot of a plane has strayed off the course he has filed, it is difficult.

22. As already noted, identification at the Information Center is accomplished by comparing the information received from observers (as portrayed on the plotting board) with the information obtained from filed flight plans of friendly aircraft. To facilitate identification, as well as because such information is extremely important in the event of an enemy raid, ground observers are required, whenever possible, to identify aircraft seen.

23. For the purposes of this manual, it will be assumed that the reader is familiar with the process of filling out a flash message form and reporting the information thereon, by telephone, to the Filter Center. The portion of the form with which we are here concerned is Column 2, entitled "Identity of Airplanes."

24. Identification of aircraft means to identify a plane as a P-40, B-17, Spitfire, etc. Since many aircraft are known by two or more names or type numbers, the approved standard designation to be used by ground observers on flash messages is indicated for each silhouette contained in this manual. In order to avoid confusion, it is important that ground observers adhere to the standard designation indicated. This designation will be entered by the observer in Column 2 of the flash message form. A typical entry on the flash message form identifying an aircraft would, then, appear as follows:

25. Although identification of visible aircraft is not difficult once certain fundamental principles are firmly understood, there will be some instances in which identification will not be possible. The observer may be unable to do more than give the number of motors, and even this may be impossible when visibility is bad or when the aircraft is flying at a very high altitude. In such instances, the observer should report the number of motors, if known, or report the identification as "unknown," rather than delay his report. He should note the salient features of the plane mentally, however, if he is able to see it, and try to identify it after his report has been sent. An Army representative at the Filter Center is liable to call back in an attempt to effect positive identification.

26. To sum up then, the observer should report in column 2 of the Flash Message Form one of these three things:

a. Preferably the identity with no reference to number of motors.

b. As second choice the number of motors. This should be reported only when identification cannot be established.

c. Unknown—as a last resort to avoid delay in making the report or when the plane is not seen.