28 Sept. 1951
From: Chief of Naval Operations To: Distribution List Subj: Radar Bulletin No. 8A (RADEIGHT-A); Change No. 2 Encl: (1) Chapter 13-A of RADEIGHT-A
1. Enclosure (1) is a new chapter of RADEIGHT-A. It is directed that this chapter be inserted between pages 144 and 145 in subject publication.
2. In addition it is directed that the following changes be entered in pen and ink. The date of entry of Change 2 will be indicated on the inside of the front cover.
Chapter 10, page 81, second column, lines 14H and 15:
Delete the words "low-flying" from the sentence beginning, "Frequently a CIC officer on a picket ship, etc...." Delete the word "a" and insert "an" line 14 page 81.
Chapter 10, page 82, first column, change first sentence of section 7 to read:
"The CAP is flown in the vicinity of the force it is covering."
Chapter 10, page 83, first column, second sentence, second paragraph, change to read:
"It is imperative that the CAP stations be reassigned as the tactical situation dictates, in preparation for any subsequent attack."
Chapter 10, page 88, second column, change the first sentence in section 3 to read:
"The RAPCAP is launched by a carrier group (unit) (ship) and is under the control of the ship designated by the TGCICO, while en route to and from station."
J. W. Jamison,
CHANGE NO. 2 TO RADAR BULLETIN EIGHT-A
HIGH SPEED, HIGH ALTITUDE INTERCEPTIONS
B. AIR CONTROL TECHNIQUES.
C. STATIONING AND ORBITING THE CAP.
This chapter has been written to supplement the two preceding chapters in accordance with the note at the head of page 129. The information in this chapter should not be construed as replacing any of the foregoing material. The proven basic methods of intercept control still obtain, though there are some noteworthy differences in effecting air intercept control with turbo-jet aircraft as opposed to piston engine aircraft.
Any qualified air controller can learn to effect high-speed intercepts after reasonable practice against high-speed raids. It is important that controllers have the support of the CIC team. Radar operators must quickly and accurately give ranges and bearings from the PPI without resort to cursor or range bug. Plotters must keep continuous tracks on the air summary plot, without allowing the display to degenerate
into a series of disconnected and scattered plots. Radars must be maintained at their absolute peak performance since turbo-jet aircraft, due to their aerodynamic "cleanness," may not reflect radar pulses as effectively as piston engine aircraft.
The controller working with jet aircraft will also find it necessary to be much more familiar with the performance capabilities and limitations of the planes under control. Since turbojet engines are characterized by widely varying fuel consumption rates and, in general, will realize greatly improved fuel economy at high altitudes, the controller must keep himself informed of the "state" of aircraft under his control, and must employ them, whenever possible, with fuel economy as a major consideration.
B. AIR CONTROL TECHNIQUES
In general, the controller making an intercept with turbo-jet aircraft should use all-weather intercept voice procedure and vocabulary, since the entire action is speeded up, with less time for call signs and extraneous instructions.
The greatest problems confronting the controller who is using turbo-jet aircraft to defend against high-speed raids result from the high closing speeds between interceptor and bogey. With closing speeds of 800 knots and greater, a small error in timing the fighter's turn to attack will result in a large displacement error.
The problem is further complicated by the effect of poor radar information on jets. In order to alleviate the latter, Mk 10 IFF, when available, should be used to the maximum in tracking the CAP. When either target or fighter have been lost, dead reckoning on the PPI is mandatory. A dot must he made with grease pencil for each antenna rotation at the point where the aircraft shows or should show.
Good DR work by the controller may make the difference between an interception and a miss. In the continued absence of either IFF or radar response, having the fighter turn will frequently result in a radar blip since his effective radar reflecting area varies greatly with different aspects of the aircraft.
If, when DR'ing a fighter, the calculated time comes to give him a vector, the turn must be made on the basis of DR information alone. The controller should not wait for a blip, for if the turn is more than slightly late the fighter will end up many miles astern of the bogey and a long tail chase or a complete miss will result.
Under all conditions of poor radar information the controller should so inform the pilot, so that the pilot may maintain safety of flight with respect to other aircraft or dangers to air navigation without dependence on the controller.
It is also important that the controller use bold cut-off vectors to insure that the interceptor is in such a position that tally-ho will be made with the interceptor on the bow of the bogey--the best attack position. If tally-ho is not made while on the cut-off vector, a fighter with small speed advantage over the bogey must be ordered onto a heading parallel to the bogey's course to permit him to remain forward of the bogey while searching.
Vectors should be handled cautiously when general-purpose fighters are being employed for the intercept and are temporarily operating in an overcast. If at all possible, planes in an overcast should be kept in a steady condition of flight since maneuvers in weather may result in pilot vertigo or loss of formation. Accordingly, pilots should be instructed to notify controllers whenever they enter an overcast, and conversely controllers should require frequent weather reports in order to avoid the necessity for giving vectors under these circumstances.
When contrails are lacking a preferred position for the jet fighter is with the target above and forward of the beam. This is not the best attack position, but it does afford the best opportunity for sighting. On the other hand, when contrails are present, positioning the fighter for optimum sighting will not be much of a problem, since tally-ho should be made at extreme ranges. The controller need only vector the fighter for earliest possible intercept and let the pilot take his own best attack position. In this connection, and when otherwise feasible, controllers should station fighters under their control at altitudes where contrails do not form in order to avoid unnecessary disclosure of the CAP's position.
C. STATIONING AND ORBITING THE CAP
Time-proven basic procedures for stationing and handling the CAP still hold with high-speed interceptors. However, it may be possible under certain circumstances to keep a minimum of CAP actually airborne, while other high performance fighters are kept ready for immediate scramble on the carrier deck. This system requires good coordination and control, and can be used only when it is definitely known that sufficient early warning will be available, as with an extensive picket system, to get the on-deck CAP airborne, on proper heading, and at altitude in time to intercept the raid before it is in an attack position.
In order to minimize fuel consumption, the jet CAP should be placed on station at altitudes greater than 20,000 feet since turbo-jet engine fuel consumption increases rapidly below that altitude. It follows that orbit speeds or vector speeds should always be those resulting in best fuel economy at the given altitude consistent with the tactical situation. As a general rule of thumb, piston engine fighters should be used in making interceptions up to 15,000 feet whenever possible. Whenever twin engine jet fighters are being employed as an orbiting CAP it should be borne in mind that it is often advisable to place the aircraft on single engine operation in order to conserve fuel.
Visibility will have an effect on the amount of CAP that can be maintained in the air and on station since a high altitude CAP mav not be able to anchor visually on a ship as a reference point. When overcast or other low visibility conditions preclude such visual holding orbits, the number of CAP that can be effectively handled is considerably decreased. In any event, eight sections or elements of aircraft are about the most that can be adequately controlled near the main force.
It is usually best practice to hold the CAP on a bearing and distance from the control ship which will assure good radar information on them, whether the CAP can see the ship or not. This is particularly true for a CAP which is orbiting at 20,000 feet or more, since the orbit diameters will increase with the CAP's altitude. The result is that when an overhead CAP is given a vector it is likely to come out of the radar clutter area, or the cone of silence, in a tactically poor position. On the other hand, when the planes are held near their assigned station on a bearing where the air controller can see them on his scope their position is always known to him, and the initial vector will be more nearly correct. At the same time, the controller will be afforded an
opportunity to arrive at a reasonable estimate of the force and direction of the winds aloft.
A secondary advantage of keeping the CAP on a controlled orbit is that it reduces traffic on the CI net by minimizing the relay of CAP information between the controlling ship and the OTC.
When holding jets on station in tins manner it is usually best to do so at a range of 25 to 30 miles from the control ship. Since the fighters may not.show up even at this range on every sweep of the radar, it is still necessary to dead reckon carefully along the legs of the holding vectors. Determining the force and direction of the winds aloft assumes great importance in high altitude work, since winds as great as 100 knots may be encountered. It can be appreciated that such a wind will have a very considerable influence on interceptions, and that an allowance of as much as 20° or 30° to compensate for drift may not be unusual.
Perhaps the best type of holding pattern is a long rectangle since this affords a good opportunity for determming wind. Although this holding pattern requires strict attention on the part of the controller, a reliable track can be kept on the plane. On the other hand, circular or figure of eight patterns do not afford as good an opportunity to judge the wind, and will require frequent adjustment as planes drift off station. However, circular type patterns will yield a higher percentage of radar returns due to the increased reflective area of the plane presented to the radar, and so may be preferred at times when radar information is critically poor.
There is even greater necessity for holding the CAP on station under night or low visibility conditions. Pilots may be skillful enough to hold over the ship, using electronic aids available to him, but this method should be used only as a last resort.
When a RAPCAP is being vectored out from the carrier to a picket which is to exercise
control, it can be ordered to climb to assigned altitude at the same time. Since many of the outlying ships being used for pickets will not have electronic navigation aids, it will frequently be necessary to closely control the RAPCAP's as they proceed to their assigned stations. This means that each ship along their course must control them, passing control along to the next ship until they arrive on station.
When enemy raids offer real business for the controllers, the CAP under control of the pickets should be used to hit the raids early. In general, this RAPCAP should be vectored inside the outer line of pickets in pursuit of a raid only when he has a good chance to effect an intercept. If the RAPCAP can't reach an attack position by the time the raid is over the outer picket stations, it should normally drop the chase, providing there is a backstop CAP available.
If this first RAPCAP does have to break off, but manages to make tally-ho, information from the RAPCAP regarding the raid and its composition should be passed on to the backstop CAP. Even though the outer RAPCAP might be at a lower altitude or of inferior speed, it should be used to try for a tally-ho in the hope of gaining this information on the raid. Altitude information gained in this manner may prove especially valuable. However, the RAPCAP should not be pulled so far off station that a hole is left in the outer defense.
When altitude information on a raid is being supplied by height finding radar, the CAP should be initially ordered to an altitude equal to the raid altitude plus the known maximum error likely in the radar.
If the intercept is being conducted under high visibility conditions, and the PPI indicates that the pilot should have made tally-ho. he should be dropped in 5,000-foot increments until he has done so. Normally in conducting high visibility intercept, a quick check at each 5,000-foot level will suffice.
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