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The D-Day Fighter Control Story

 

A Briefing Paper

by

The Association of RAF Fighter Control Officers

Acknowledgement

This paper has been compiled from a number of sources. Squadron Leader Mike Dean and Mr Peter Best generously provided information and advice and a particular debt is owed to Doctor Les Dobinson for his advice and contribution which was special, because he was actually there on Omaha beach on D-Day. Some facts have been taken from Government sources and under the terms of the standard Open Government Licence we would like to acknowledge the importance of Air Publications 1063, 3237 and 1116 which were produced by the Air Historical Branch in the 1950s.


Fighter Control During the Assault Phase of Operation Neptune - 6th June 1944


Introduction

By 1944 there was a wider understanding amongst the air planners that control of the air was a primary responsibility for the air force. Experience gained in the Battle of Britain, the Western Desert and Mediterranean had shown that success in controlling the air was dependent upon a system of command and control that used radar to provide warning of attack and a tactical picture of the airspace for battle management and weapon control. Radar prevented the enemy aircraft mounting surprise attacks but, with intelligent battle management, could also be used to surprise the enemy. Moreover, the lessons from North Africa had also shown the value of radar cover beyond the front line to help direct offensive operations.

The section of the French Coast selected for Operation Neptune, which was the code name for the assault phase for the liberation of Europe, otherwise known as D-Day, was over 80 miles from the English coast. South coast radar units could provide cover over the beaches but the coverage was not good enough to provide advance warning of enemy aircraft approaching the beaches or effective control of the air. It was necessary, therefore, to extend the coverage for both picture compilation and control and to establish, at the earliest possible time, mobile radar units ashore in France to control the air above the advance into France.

Once again experience from the Mediterranean, especially Operation Husky, the invasion of Sicily, had thrown up many valuable lessons. One of these lessons was that radar units providing control of the air and the control of offensive operations as part of a composite RAF Group could not also provide picture compilation and the control of day and night fighters in the base areas and behind the front line. More simply put, radar units could not support both offensive operations and provide air defence of the defended area behind the front line. Another lesson was that picture compilation, which included the complete analysis (known as filtering) and identification processes, should be collocated with the Operations Centre for composite Groups and so these 2 operational capabilities were combined into one Group Control Centre (GCC). Prior to this, the picture had been constructed and maintained by a separate Mobile Raid Reporting Unit.


The Air Organisation for Operation Overlord

All US and UK air forces assigned to Operation Overlord - the liberation of Europe - were placed under the command of the Commander-in-Chief Allied Expeditionary Air Force (AEAF) with the RAF managing all air operations in the British area of responsibility and the USAAF managing air operations in the US area of responsibility.

Figure 1 - AEAF Organisation

In the UK area, the plan was that No 85 Group would provide air defence behind the front line and - especially - all the base areas. The Second Tactical Air Force was to prosecute the forward air battle, including close support to the armies. It comprised 2 composite Fighter and Fighter Bomber Groups - Numbers 83 and 84 Groups - and a Medium Bomber Group - No 2 Group. Surveillance and Control units providing early warning and control were assigned to Numbers 83 and 84 Groups. Generally speaking, No 83 Group worked with the Second British Army and No 84 group worked with the First Canadian Army.

The forward battle was fluid and control of both offensive and defensive air did not lend itself to the defensive structure that had been established in the UK. However, the defence of the base areas was modelled more on the UK system and 3 base Defence Sectors were established under the Group Commander. The organisation is shown at Figure 1.

 


Operation Neptune

Operation Neptune covered the assault phase and was all about establishing a firm bridgehead ashore by D-Day+1. The responsibility for the control of the air was vested in the Commander-in-Chief of Air Defence of Great Britain (ADGB) - formally Fighter Command - which was based at RAF Bentley Priory. The AOC-in-C delegated the operational control of air forces to AOC 11 Group. The challenge for the air surveillance and control system was to provide adequate forward cover and the seamless transfer of control of the air to Number 85 Group once a bridgehead had been established.

Figure 2 - FDT Filter Table
Courtesy of Mike Dean

The plan that was formulated required a total of 3 Landing Ships Tank (LST) to be converted as air surveillance and control ships; these were designated as Fighter Direction Tenders (FDT). The interesting point is that the FDTs, in addition to early warning and control, also undertook the full picture compilation role with their own Filter Centres and Identification teams. A picture of a Filter Centre in a FDT is shown at Figure 2. The FDTs were Royal Navy units under the command of the Allied Naval Commander of the expeditionary naval forces but were operationally controlled by AOC 11 Group.

Figure 3 - Type 15 Aerial on a FDT
Courtesy of Mike Dean

Figure 4 - FDT 217

The concept of using ship borne RAF radar equipment for surveillance and control was first trialled in North Africa and then used during Operation Husky when LST 305 was fitted with Ground Control Interception (GCI) radar (the Type 8 then used by GCI units in the Mediterranean at the time), control equipment and radios. The D-Day FDTs were equipped with the Type 15 and the Type 11 radars both fitted with Mark III IFF interrogators/responders, Aircraft Interception beacons and VHF radio telephony and wireless telegraphy sets. The term GCI was a rather interchangeable term that was used to denote radars that could be used for close controlled interceptions but also for those which were primarily control units although they also had an early warning and surveillance role. The FDT system proved so successful the AOC-in-C Fighter Command pressed for 4 FDTs to support Operation Neptune. Three were produced:

Figure 5 - FDT 13

  • No 216 FDT. This FDT was positioned seaward of the US beaches in the western half of the assault area. Its role was to produce a tactical picture over the US area, provide raid reporting and to control both RAF and USAAF fighters tasked to operate in the area.

  • No 217 FDT. This FDT was positioned seaward of the British beaches in the eastern half of the assault area to undertake the same role as FDT 216. However the ship was designated as the main coordinating FDT or Master Control FDT; the senior RAF controller was aboard this ship. The Master Control FDT had the additional role of managing fighter resources across the whole assault area.

  • No 13 FDT. This FDT was positioned in the main shipping route to provide defensive cover over the shipping lanes.

The FDT positioning in relation to the air corridors, shipping lanes and assault beaches is shown at Figure 6 below.