British Pathfinder Operations as at March 1944

British Pathfinder Operations as at March 1944

Issued by Luftwaffenfuhrungsstab Ic/Fremde

Luftwaffen West

Preface

The success of a large-scale night raid by the RAF is in increasing measure dependent on the conscientious flying of the Pathfinder crews. The frictionless functioning of the attack is only possible when the turning points on the inward and courses, as well as the target itself, are properly marked. Lately, these attacks have been compressed into about 4 minutes for each wave averaging 120-150 aircraft

Dense and high reaching clouds, which hide the sky markers over the target, and exceptionally strong winds which blow the markers away quickly, represent an unpredictable barrier to Pathfinder operations and can often appreciably decrease the efficiency of an attack.

Another reason for the failure of a raid may lie in the partial failure of the first Pathfinders, the 'Initial Markers', to arrive, since experience has shown that succeeding Pathfinders, in spite of being equipped with H2S and blind marking equipment, have allowed themselves to be influenced, to a certain extent, by the Initial Markers.
 
A: DEVELOPMENT

1.     The concentrated large-scale RAF raid on Cologne on 30/31 May 1942, during a full moon night and with an alleged strength of more than 900 aircraft, was the first attempt to imitate the 'Focal Point' raids initiated by the German Air Force during this strategic air war against the British Isles during the years 1940 and 1941.

The lessons taught by this first large-scale raid, the increasingly high losses and the fact that the Hyperbola (Gee) navigation system could only be used in certain conditions, forced the AOC-in-C of of Bomber Command to develop new systems of attack.

Using the German system of 'Illuminators' and 'Fire Raisers' as a model, the use of Pathfinders was developed towards the middle of August 1942, in order to bring on to the target all the aircraft, some with inexperienced, others with only medium-trained crews, and to allow the dropping of the bombs without loss of time.

 

2.     Air Vice-Marshall BENNET, at present still in command of these special units, was appointed Chief of the Pathfinder formations.

This 35 year old Australian - known as one of the most resourceful officers of the RAF - had distinguished himself as long ago as 1938 by a record long-range flight to South Africa in a four- engined seaplane which was launched in the air from a Sunderland flying boat (composite aircraft). In 1940 BENNET established the Transatlantic Ferry Command with aircraft of the Hudson type. As an example of his personal operational capabilities, an attack may be cited which he made on the German Fleet base at Trondheim.

BENNET's appointment as Commander of the Pathfinder Formations is also based on the fact that he has written two standard books on astro-navigation.

 

3.     The use of Pathfinders in the first large-scale raids was comparatively primitive. Several particularly experienced crews were sent out first as Fire Raisers ahead of the Main Bomber Force and, in order to facilitate and ensure the location of the target, moonlit nights were especially favoured.

Shortly after the formation of these Pathfinder groups, however, the principle of raids during moonlit nights was dropped and raids in dark cloudless periods began to take place.

BENNET strove to render the raids independent of the weather and at the same time to make it easier for the less experienced crews to locate the target.

 

4.     At first there were only four bomber squadrons, equipped with Stirlings, Halifaxes, Lancasters and Wellingtons, and in January 1943 these units were organised into No 8 Bomber Group, the Pathfinder Group.

The grouping of the Pathfinders into a Bomber Group of their own made it possible to standardise the equipment and the training, to put new ideas into operation and to immediately evaluate all experiences.

During the course of 1943, the number of Pathfinder squadrons was increased to meet the increased demands, and among others, several Mosquito squadrons were detailed to the Pathfinder Group.

 

B: ORGANISATION AND EQUIPMENT

I: Organisation and Aircraft Types

1.     Eighth Bomber Group at present consists: Five Lancaster squadrons, one Halifax squadron, four Mosquito squadrons (including two special bomber squadrons with 'Bumerang' [Oboe] equipment) and one Mosquito Met Flight.

For further information concerning the organisation of these units, see 'Blue Book Series', Book 1: The British Heavy Bomber Squadron.

 

2.     In addition to the normal navigational aids (see also 'Blue Book Series', Book 7: British Navigation Systems) the aircraft carry the following special equipment:

a)     Four-engined aircraft (Lancaster and Halifax):

Rotterdam (H2S) for location of target and bombing without ground visibility;

Hyperbola navigation instrument (Gee);

Identification Friend-Foe (IFF); acoustic night-fighter warning instrument 'Monica';

visual night-fighter warning instrument (Cathode ray oscilloscope) 'Fish Pond'

provision for bomb-release in the cabin as well as in the navigation room.

 

b) Twin-engined aircraft (Mosquito)

Hyperbola navigation instrument (Gee);

special equipment according to mission, for example 'Bumerang' (Oboe)

the existence of Mosquitos equipped with H2S have not as yet been definitely established. According to latest information, this special equipment does not yet seem to have been installed in the Mosquito.

 

II: Personnel

1.     The crews are no longer composed mainly of volunteers as was formerly the case. Owing to the great demand and the heavy losses, crews are either posted to Pathfinder units immediately after completing their training, or are transferred from ordinary bomber squadrons. As in the past, however, special promotion and the Golden Eagle badge are big inducements to the crews.

At first Pathfinder crews had to commit themselves to 60 operational flights, but due to this high number there were insufficient volunteers, and the figure was decreased to 45.

After transfer to a Pathfinder squadron, a certain probationary period is undergone. The crews are not appointed Pathfinders and awarded the Golden Eagle until they have proved themselves capable of fulfilling the equipments by flying several operations (about 14) over Germany. Before the award of the Golden Eagle each member of the crew has to pass a special examination to show that he is fully capable, of performing two functions on board, for example gunner and mechanic, or mechanic and bomb-aimer, etc.

 

2.     There is a special Pathfinder school (NTU Upwood Special School). All new crews, however, are sent on a special navigational course lasting 8-14 days at a Navigation Training Unit, where particularly experienced instructors, who have already completed their pathfinder tours, train the crews in the operation of the special equipment and put final polish on their already good navigational training.

New Pathfinder crews fly training flights over Great Britain. These are usually made southwest from the Cambridge area, course being set for the Isle of Man. On the return flight, a large city, such as Birmingham or Manchester is approached, dummy bombing using H2S is carried out, and target photographs are brought back to the home base. Flights of this kind are flown to a strict time schedule, just as in the case of a large-scale raid on Germany or the Occupied Western Territories, and are taken into consideration in the assessment of the crews as Pathfinders. If, on several occasions the schedule is not adhered to, the crew is transferred to an ordinary bomber squadron.

C: PATHFINDER OPERATIONS

I:General

The operational tactics of the Pathfinders have been under constant development ever since the earliest days, and even now cannot be considered as firmly established or completed. New methods of target location and marking, as well as extensive deceptive and diversionary measures against German defences are evident in almost ever operation.

Whereas the attacks of the British heavy bombers during the years 19421-43 lasted over an hour , the duration of the attack has been progressively shortened so that today, a raid of 800-900 aircraft is compressed into 20 minutes at the most. According to captured enemy information, the plan for the raid on Berlin on 15/16 February 1944 called for about 900 aircraft in five waves of 4 minutes each.

In spite of the increased danger of collision or of dropping bombs on other aircraft which must be taken into account, the aim has been achieved of allowing the German defences, the Commands as well as the defence weapons themselves, only a fraction of the time available to them during raids in the past.

The realisation of these aims was made possible by the conscientious work of the Pathfinder group and by the high training standard (especially regarding navigation) of the crews.

The markers over the approach and withdrawal courses serve as navigational aids for all aircraft and above all they help them to keep to the exact schedule of tines and positions along the briefed course. Over the target, the markers of the Pathfinders enable all aircraft to bomb accurately without loss of time.

 

II: Markers

Up to date, the following markers have been identified:

TARGET MARKERS

a)     Ground Markers: also called cascade bombs, are red, green and yellow. Weather conditions govern the setting of the barometric fuse, whereby the Ground Marker container is detonated at a height varying from 800 to 5,000 metres, thereby releasing 60 flares which fall burning and burn out of the ground.

Ground markers are mainly dropped in the target area, but they are also sometimes used as Route Markers. Ground Markers are also dropped in 10/10ths cloud in order to illuminate the cloud base from below. When the clouds are thin, the crew can see the glare without difficulty. The average duration of burning of a Ground Marker is 3-4 minutes.

 

b)     Sky Markers: parachute flares, of which several are usually placed simultaneously. As a rule, the flares used are red ones from which, at regular intervals, quick-burning green flares ('dripping green stars') drop out.

Besides these, green Sky Markers with red stars asn , although comparatively seldon, green Sky Markers with yellow stars are also used.

The bomb aimers are for the most part briefed to drop their bombs into the middle of a group od Sky Markers. This corrects the opinion held until now that two sky markers are set, one to indicate the point of bomb release and the other to indicate the target.

 

c)     White and Yellowish Flares: used chiefly to illuminate a target. They are also sometimes used as dummy markers.

During raids in the autumn of 1943, the enemy attempted to mark a target approach corridor by setting numerous flares. It may be assumed that he dropped this system because of the heavy losses inflicted by German single-engined fighters in the target area.

ROUTE MARKERS

a)     As Track Markers: or Indicators, Sky Markers are used in 10/10ths cloud.

b)     Ground Markers: (Spotfires) are red, green or yellow; red and yellow are mainly used. A ground marker does not split up into different traces, but burns with a single bright light for from 3-8 minutes.

NEW KINDS OF MARKERS (as yet not clearly identified)

The enemy has often tried to introduce new kinds of markers with varying lighting effects:

a)     Among others, a quick-falling flare bomb was observed lately. After it hit the ground, 1 90 metre high column of sparks was observed, which slowly descended in many colours. Confirmation, however, is not yet available.

b)     To designate the beginning and the end of the attack, a large reddish-yellow 'Fireball' has often been observed. Red flares fall from the Fireball and at low heights these again split up into green stars. The light intensity of these bombs is unusually high.

c)     The so-called red 'Multi-Flashes' are apparently used as Route Markers,. They have been observed sparkling to the ground at intervals of 2-3 seconds.

d)     The enemy seem to have stopped using enormous 1,800 kg size flare bombs. The reason for this could not be determined.

III: Execution of Pathfinder Operations

DIVIDING OF TH PATHFINDER CREWS

a)     At present, Pathfinder crews are divided into the following categories:Blind Markers, Blind Backers-up, Visual Backers-up, Visual Markers, Supporters - Pathfinder Main Force.

About 15% of the bombers used for a large-scale operation are Pathfinders. For example, out of a strength of 900 aircraft, 120 would be Pathfinders, of which about 20 to 25 would be Blind Markers, 30 to 45 would be Blind and Visual Backers-up and 60 to 70 would be Pathfinder Main Force.

b)     Blind Markers: It is the duty of the Blind Markers to locate the target using H2S and to set Ground or Sky Markers, or both, according to weather conditions, at zero hour minus 2 to 5 minutes.

The Blind Marker crew are responsible for the success or the failure of the raid. They are more strictly bound to the time schedule than all the other aircraft taking part in the raid. They are not allowed to drop their markers if the schedule is deviated from by more than one or two minutes, or if the instruments fail, or fail to indicate accurately. In such cases the Blind Marker aircraft automatically becomes part of the Pathfinder Main Force and must drop its HE bomb load exactly at zero hour.

With smaller targets, it is the duty of the Blind Markers to set flares over the target area, in order to illuminate it.

Another duty of good Blind Marker crews during the initial stages of the attack is not only to set new markers, but also to re-centre the attack. Experience has shown that the first aircraft of the Main Force drop their bombs near the Markers but that succeeding aircraft tend drop them short of the target area during the progress of the attack. It is the duty of the Blind Markers detailed for this purpose to bring the bombing back to the original target by resetting the Markers past the first aiming point in the direction of withdrawal.

For several months past, the Blind Markers have had a further duty, In several operations it was repeatedly shown that errors in the navigation of the Main Force occurred owing to inaccurate wind forecasts. Experienced Pathfinders were therefore instructed to transmit their established wind calculations to England by W/T. Each Group picks up these reports and transmits them every half-hour to the airborne bombers.

c)     Blind Backers-Up: The duties of the Blind Backers-up are similar to those of the Blind Markers, except that they fly in the bomber stream. Thus, they drop their Markers during the attack, also in accordance with a strict previously laid down time schedule. Blind Backers-up are used to set Ground Markers and, above all, Sky Markers, which are always renewed by means of H2S and never visually.

d)     Visual Backers-Up: In order to give new Pathfinder crews a chance to gain experience for future operations as Visual or Blind Markers, they are allowed to set the new Markers visually; these, however are always of a different colour. Theoretically, these Markers should be on, or very near, to the original Markers, but as in practice this is very seldom the case, the impression given is that of the target being framed by markers. The bomb-aimers of the succeeding bombers are therefore briefed to release their bombs in the centre of the markers dropped by the Backers-up.

e)     Visual Markers: An attack on a small or pin-point target (definite industrial installations, dockyards, etc) necessitates still more accurate marking than is possible by the Blind Markers. The Visual Markers, therefore, locate the target visually from medium height, sometimes from as low as 1,500 metres, and then release their Ground Markers on the centre of the target, in order to concentrate the attack of the high-flying bombers. The Visual Markers are aided by the illumination of the target area aided by several Blind Markers (Newhaven attack).

f)     Supporters: New crews who come from training units or other squadrons and who are to be trained as Pathfinders, fly their first operations in the Pathfinder Main Force. They carry only mines or HE bombs, arrive exactly at zero hour and try, at the first concentric bombing, to create conditions necessary to allow the incendiary bombs of the succeeding waves to take full effect.

 

ROUTE MARKERS

Route Markers are set buy good Blind Marker crews and are renewed during the approach of the Bomber Stream by further good Blind Marker crews. Ground Markers (Spotfires) are sometimes set visually, and sometimes by instruments, but Sky Markers used as Track Markers or Indicators are set only by means of H2S.

The route of approach and withdrawal are generally identified by three Markers set at especially prominent points or turning points. The colours of these markers for any single night raid are usually the same: either red, green, yellow or white. It has often been observed that the Route Markers do not always lie exactly on course. They are set somewhat to one side so that the approaching bombers are not unnecessarily exposed to the danger of German night-fighters.

 

TARGET MARKERS

The Target Markers will differ according to weather conditions. More Sky or Ground Markers are set, according to the visibility and cloud conditions prevailing. Up to date, the following methods of attack and target marking have been recognised:

a)     The 'Parramatta' attack under a clear sky and with good visibilty. Ground Markers are used only.

b)     The 'Wanganui' attack with 8-10/10ths cloud cover. Sky Markers only.

c)     The 'Musical Parramatta' attack with 5-8/10ths cloud cover. Mainly Ground Markers, but some Sky Markers.

d)     The 'Newhaven' attack, in which the target area is illuminated by means of parachute flares, coupled with several Ground Markers.

e)     The 'Musical Wanganui' attack with 8-10/10ths cloud cover. Mainly Sky Markers, but some Ground Markers. This system of target marking has been used to a great extent lately during bad-weather operations.

 

DROPPING THE MARKERS

The setting of the Pathfinder Markers requires a great deal of experience. For this reason, training flights with Markers of all kinds are often carried out over Great Britain, serving for practical experiments with flares as well as for training purposes.

When the target area is already illuminated by previously dropped flares, the Ground Markers are released visually by means of the ordinary bomb-sight. In cases where 10/10ths cloud or dark conditions are found over the target area, H2S is used for dropping all Markers.

A great deal of experience is required for the setting of Blind Markers. Close co-operation between the navigator and the H2S operator (see 'Blue Book Series', Book 7: British Navigations Systems for the difference between the two) who sit side by side in the navigation room, is the first essential for the precise setting of Markers by means of H2S. Above all, drift must be calculated before the Markers are set, so that the Main attacking force has only to navigate on the Markers themselves.

 

NAVIGATION

The basis for all Pathfinder navigation is dead reckoning, and all other systems are only aids to check and supplement this. H2S equipment is valueless without dead reckoning because the ground is not shown on the cathode ray tube as it is on a map.

To facilitate the location of the target, an auxiliary target, which experience shows to give a clear picture on the cathode ray tube, is given during briefing. This auxiliary target should be as close to the actual as possible, in order to eliminate all sources of error. Cities, large lakes, or sometimes even coastline features are used as auxiliary targets.

The course and the time of flight from the auxiliary target to the actual target are calculated in advance, taking the wind into consideration. The H2S operator then knows that the main target will appear on the screen a given number of seconds after the auxiliary target has been identified.

 

MOSQUITO PATHFINDER OPERATIONS

The Mosquito aircraft have special duties as Pathfinders, concerning which the following information is available:

a)     Setting Ordinary Markers: 15 to 20 minutes before the beginning of the actual attack, in conjunction with other Lancaster Pathfinders, over an auxiliary target.

b)     Setting Dummy Markers: along the coast and at other places to indicate a false course and a false target.

c)     Dropping so-called 'Fighter Flares': these are imitations of the white and yellow flares dropped by German flare-carrying aircraft, to attract and divert German night-fighters.

d)     Dropping 'Window' from great heights: this is so timed, after taking wind conditions into consideration, that a cloud of Window will be over the target when the first four-engined Pathfinders get there. This is made necessary by the fact that the target must be approached in straight and level flight, without evasive action, in order to get a good H2S picture. It is supposed to eliminate to a great extent aimed (radar) fire by the Flak.

e)     Release of Single HE Bombs: 20 to 30 minutes after the main attack and observation of the results of the main attack.

f)     Identification of pin-point targets: for succeeding Mosquito waves by setting Ground Markers with the aid of 'Bumerang' (Oboe). The succeeding Mosquitos then drop their bombs visually on the marked target.

D:CONCLUSIONS

1.     Strong criticism from amongst their own units was at first levelled against the British Pathfinder operations, but they were able to prevail because of the successes achieved during the years 1943/44.

2.     The original assumption that the majority of bomber crews would be less careful in their navigation once they became used to the help of the Pathfinders, and that therefore the total efficiency and success of raids would diminish, has hitherto not been confirmed. The navigational training and equipment of the ordinary British bomber crews has also been improved.

3.     The operational tactics of the Pathfinders cannot be considered as complete even today. There are, in particular, continual changes of all markers and marking systems.

4.     The trend of development will be towards making possible on one and the same night two or more large raids on the present scale, each with the usual Pathfinder accompaniment.

 

Distribution:

Units of the Rdl an Obdl

Luftflotten down to operational Gruppen

Flakabteilungen an Ln Regiments

 

(Source: No 61008 Secret Ic/ Foreign Air Forces; A/Evaluation West)