PROJECT 1947 - "Operation Charlie" by David Clarke

EVENING STANDARD

(London), 29-4-47, pg 3

RADAR 'GHOST' MAY BE A V-1, RADIO-CONTROLLED

Evening Standard Air Reporter

A "ghost" airplane, plotted on Fighter Command's radar screens flying at night over the North Sea may have been a radio-controlled machine of the flying-bomb type. If it was, it was not British.

Twice the "ghost" airplane, which has still not been identified, showed on the radar screens.

That was several weeks ago. Since then Fighter Command radar watchers have been on the look out but, I understand, the "ghost" airplane has not reappeared.

Suggestions that smugglers were bringing contraband into Britain over the Norfolk coast at night can be discounted. The "ghost" did not cross the coastline.

It stayed on the radar screens only a short time, but long enough for Fighter Command's experts to work out that the "ghost" was a peculiarly behaved machine.

There were sudden erratic speed changes, I was told at the Air Ministry. The "ghost" would travel at 425 mph, suddenly drop back to 120 mph.

Big variations in its height, too, were noticed, and it also had a rapid rate of climb.

A pilotless aircraft, controlled by radio from the ground or from a ship, could suddenly change speed and height without the life of any pilot being risked.

"Telemetering" devices would record to the controller the machine's performance.

Abstract

Six months before Kenneth Arnold's seminal sighting of a formation of nine strange objects above the Cascade Mountains, unidentified flying objects were tracked by Britain's Air Defence radars.

"Flying Saucers" and UFOs were concepts that had not been invented when a RAF station placed an urgent call to HQ Fighter Command reporting an unusual blip moving towards the English coast. It was January 1947, and the war-weary country was bracing itself for the arrival of some of the most severe winter weather ever experienced in Britain. As temperatures fell below freezing, gale force winds were followed by six weeks of heavy snow. Public transport ground to a halt and the Government were forced to set up a “crisis Cabinet” as power cuts plunged the country into chaos. In the midst of this ferocious winter eastern England began to receive visits from what the RAF described in official records as ‘an unidentified high-flying aircraft’. This ‘ghost aircraft’ was by definition an ‘unidentified flying object.’

This paper summarises all the available information relating to these important, pre-Kenneth Arnold incidents from the UK. It is based upon evidence collected from official files held by the Public Record Office (PRO) in London, newspaper archives and interviews with former Royal Air Force personnel who played a part in Operation Charlie.

During the course of the research into these incidents we appealed for information from RAF aircrew and fighter control personnel who served during the post-war period. We received two replies from senior RAF officers who had been present when unusual echoes were detected by Britain's air defence radar system. The initial incidents occurred during the period 1945-47, immediately before and after the "ghost rocket" wave in Scandinavia. At this time Flight Lieutenant Geoffrey Easterling was posted to the Filter Room at RAF No 12 Group, Watnall, Nottinghamshire, where information from coastal radar stations was collated and plotted. 12 Group was responsible for the air defence of a large swathe of the English east coast and North Sea approaches. Easterling recalled:

"During this time incidents of very high-flying aircraft were not too uncommon. There were lots of what we called X-raids picked up on the long-range Chain Home radars – unidentified, high-altitude and spasmodic. They did not register with any of the civilian airlines and they were too high for that. Whilst I remember the events of January 1947 I can also remember one or two similar approaches whilst at Watnall from late September 1945 into January 1946. These were very high. They came over the top of the lobes at 35,000 feet estimated and very fast. This caused a bit of panic and doubt as that sort of height was much beyond any of our aircraft (which we knew about). There was of course talk of Russian spy planes monitoring our radio frequencies and our R/T communications. It was suggested they had devices which could ascertain the limits of our radar (by an internal device which they had), but all of this was a bit "pie in the sky" and of course Top Secret in those days – it was all treated with a great deal of doubt and suspicion, no doubt because such heights and speeds had never been seen by the old hands with wartime raid reporting experience." [1]

Flt Lt Easterling remains convinced these high-flying tracks were Soviet aircraft flying to and from bases in occupied Germany. "It was a fairly common thing during the Cold War," he said. "We put these X-raids down to Russian bears. Sometimes aircraft were scrambled but nothing was seen."

Suspicion of Soviet intentions in Western Europe was endemic and in 1947 the former Prime Minister, Winston Churchill, made his famous speech describing how an "Iron Curtain" had descended across the European continent. It was logical, in this climate of mutual hostility, that Britain's defence chiefs would consider the possibility that the "ghost planes" tracked over the North Sea were a form of advanced Russian intruder aircraft, developed using cutting-edge German technology captured at the end of the war.

The mysterious radar echoes first came to attention of the public when the London Daily Mail splashed a story across the front page of its 29 April 1947 edition. The headline was: "Ghost plane over coast, RAF spot it – can't catch it":

A "ghost" plane which flies in over the East Anglia coast near Norwich at midnight at a great height and disappears inland is puzzling the Royal Air Force. All attempts at interception have so far failed. Crack night-fighter pilots have been sent up in Fighter Command's latest Mosquitoes, but the mystery aircraft has got away every time. It always crosses the coast at roughly the same spot, and it has used such effective evasive tactics that it is thought to be equipped with radar to give warning of the approach of intercepting aircraft. Time and again Fighter Command radar operators, plotting the ghost plane's course over East Anglia, have watched the "blip" go right across their screen and disappear as the plane penetrated deep inland. They have watched vainly for the "trace" to reappear, moving in the opposite direction, as the plane flew back out to sea. Some experts suspect that the plane is engaged in a highly organised and lavishly financed smuggling operation, using one or more secret landing places. According to authoritative information the plane – of unidentified type – has a speed of nearly 400 mph and a fast rate of climb.

When questioned the Air Ministry refused to speculate upon the identity of the "ghost plane" but they did admit that Fighter Command had twice received what it described as "some extraordinary plots" from its coastal radar stations. The "ghost plane", according to the Daily Mail, had displayed "enormous height range and remarkable speed variations" of between 400 and 425 mph, in excess of the top speed achieved by Britain's night-fighters, the Mosquitoes, that were slowly being replaced by the new Meteor jet for QRA duties. [2]

This ghost plane or "UFO" was listed in RAF records as "X-362". The designation "X" for X-raid was allocated to numbered radar tracks that could not be identified, and were assumed to be hostile. Early in 1947 one "X" had become so familiar to officers in Fighter Command's operations room that they invented a nickname – "Charlie." The scheme to trap and intercept target X became known by the code-words: "Operation Charlie".

In the post-war era, Britain's air defences continued to rely upon the Chain Home (CH) radar system for air defence. CH was a network of coastal stations characterised by aerials mounted on tall wooden towers. CH appears crude by today's standards but the stations were at that time the most advanced Early Warning system in the world. Radar was developed in great secrecy before the outbreak of war and by 1939 its coverage stretched from the Isle of Wight to the Scottish border. CH gave Fighter Command advanced warning of enemy aircraft approaching the English coast and the development of Ground Controlled Interception (GCI) made it possible for fighters to be guided towards them. Chain Home allowed the RAF to win the Battle of Britain and ensured that radar would play a major role in future air defence systems.

On occasions in 1939 and again in 1941 before the Battle of Britain, stations on the CH chain had detected unusual echoes approaching the English Coast that were reported to wartime Filter Rooms and RAF Fighter Command. On several occasions fighters equipped with early versions of airborne radar were scrambled to investigate but nothing was found and the phenomena were attributed to anomalous propagation (AP) or "unusual atmospheric conditions." [3] As Britain was fighting a war no in-depth investigation of the reports was made by the scientific staff, but the Air Ministry were becoming aware that the radars which helped to defend the British coast were prone to AP and other spurious returns nick-named "angels" which could on occasion be interpreted as intruder aircraft.

At the end of the war the CH chain was largely mothballed and with power shortages only the GCI stations remained active, mainly in daylight hours. Once or twice per month the system was switched on for a time during the evening for "Bullseye" training exercises organised by Bomber Command. These involved convoys of lumbering wartime bombers flying south from their bases in Lincolnshire and Yorkshire. On reaching the coast they would cross the North Sea towards the Low Countries as the GCI's guided fighters onto their tails to simulate "live" interceptions.

On the evening of 16 January 1947 Flight Lieutenant David Richards was a senior controller and 2nd in Command of the filter room of RAF No. 11 Group, Bentley Priory. This was situated in the grounds of Hill House, a large Victorian mansion at Stanmore, northwest of London. A Bullseye exercise was in progress, involving mosquitoes of 25 and 29 Squadrons, from RAF West Malling in Kent. Two aircraft from 29 Squadron were operating off the East Coast under the control of the GCI at Trimley Heath, near Felixstowe, Suffolk. GCIs reported to 11 Group Operations Room at Uxbridge, who 'told' their plots to the Filter Room at Stanmore. The first clue that something unusual had happened came when Richards received a call on a landline. He recalled:

"Trimley came up on my direct phone to report a strange plot which was either stationary at a great height or moving erratically at a great speed and then stopping again. If this was a conventional aircraft it would have travelled in a straight line, but it did not do that. This was not an aircraft, it was something very odd. 400 mph [quoted in the Daily Mail] is a pretty disappointing figure, as it is within the range of some 1947 aircraft types. Somebody – either at one of the [radar] stations or at Uxbridge [11 Group Operations Room] – had computed speed between the rather intermittent plots and had come up with a startling figure of 1,000 mph." [4]

A speed of 1,000 mph was truly startling, for it was not until October 1947 that US test pilot Chuck Yeager first broke the sound barrier (760 mph/1,220 kph at sea level) in a Bell X-1 rocket plane. Richards continues:

"This [estimated speed] emphasises that the thing did not appear to move in a straight course, but faded and reappeared and sometimes stood still, before fading again. Without visual identification – there was none – it would be impossible for the [crew] to be certain it was investigating the same object. Note that it [the Mosquito] carried out an interception on a Lancaster during the 40 minutes between. In this time, at even 400 mph a straight course would take the aircraft from the East Coast to Scotland! I can recall this question of plot identification arising in conversations between us, our stations and Uxbridge at the time. They [Trimley Heath GCI] were looking at the tube and could judge if the echoes were the same object or a new one. This probably gave rise to the estimated speed, based on reappearances in a different place and a different height. Trimley were interrogated on this both by ourselves and Uxbridge, but stuck to their guns. After some talk between Uxbridge and the scientific officers at the stations making the observation on the validity of their plots, not a meteorological balloon etc (which I had already done), it was decided to [divert] a Mossie to investigate." [5]

If the target was a plane, it was displaying unheard of flight characteristics. Yet if it wasn't a plane, what could it be?

Flight Lieutenant Easterling was also present at HQ No 11 Group when the incident began. He recalls the initial radar track occurred somewhere above the Dutch islands before it was acquired by the GCI. "It came across towards us during the course of an hour or so, stopping and starting, towards Norfolk where it crossed the coastline towards Lincolnshire. Mossies were the only aircraft we had that could reach that height with oxygen." David Richards corroborates this impression. He said that since initial contact was made near the Dutch coast "the object was almost certainly detected by our Chain Home stations. These did not normally operate overland and only looked seaward."

Details of the incident which followed have been preserved in the RAF operations record books (ORBs). ORBs were the logbooks compiled by RAF stations and squadrons to record daily and monthly activities, including everything from sporting events to exercises and operations. During the Cold War, security restrictions meant that few, if any, entries were made in ORBs that refer specifically to investigations of "unidentified" radar tracks. For this reason, the records for 1947 are unique as they allow us to reconstruct how the RAF reacted when confronted by the unknown.

The ORB of Eastern Fighter Sector HQ, RAF Horsham St. Faith (Norfolk), dated 16 January 1947, reveals:

'An unidentified aircraft had been plotted in WC 9585 at 38,000 ft., and Eastern Sector Ops were requested by Group to scramble a Mosquito of 23 Sqdn. to intercept. However, as there was no aircraft available with oxygen this was impossible, and Sector Ops were informed by 12 Group that an aircraft of 11 Group which was already airborne on a Bullseye exercise would try to intercept under Trimley Heath Control.' [6]

The original tracking placed the target at 38,000 feet moving on a westerly course across the North Sea. According to an Air Ministry memorandum to the US Army Air Force, the incident began 50 miles from the Dutch coast at 52' 52" N 02' 37" E. Later contacts involving Trimley Heath GCI, occurred at lower altitude, placing the "blip" level with the bombers participating in the Bullseye exercise. At Trimley Heath the station's operations log recorded how Mosquito call-sign HAIROIL 27 made an initial contact with an "unidentified" target at 2014 hours when at 17,000 feet but soon lost it. Whilst searching for the target the navigator then picked up a Lancaster or a Lincoln on his airborne radar before GCI guided him towards the "unidentified" target, whereupon:

'five other contacts [were] obtained in quick succession on X. 362 (OPERATION CHARLIE) which was chased from 2120 hours until 2202 hours when interception was abandoned due to A.I. [airborne radar] trouble. This target was completely unidentified. Height at the commencement of the interception was 17,000 feet and target descended to 6,000 feet by 2202 hours.' [7]

A brief summary of the incident appears in HQ No 11 Group Fighter Command Operations book, which reads:

The report to the US Army Air Force, attributed to "Air Ministry, Great Britain" summarises the incident as follows:

'During normal night-flying practice at 2230 hours one of British Mosquitos was vectored on to an unidentified A/C at 22,000 ft. A long chase ensued commencing over the North Sea about 50 miles from the Dutch Coast and ending at 2300 hours over Norfolk. Two brief AI contacts were made but faded quickly. The unidentified aircraft appeared to take efficient controlled evasive action.' [9]

"Evasive action" implies intelligent control and this incident raised fears that an enemy aircraft had intruded upon the exercise. However, it quickly became apparent that no Soviet aircraft could match the performance displayed by this "flying object".

The incident was also linked to another "X raid" tracked by radar earlier that same day. Shortly after 12 noon, Meteors of 74 and 245 Squadrons from RAF Horsham St. Faith were involved in interception practice under the control of the GCI at RAF Neatishead when an unidentified target was tracked at 30,000 feet over Norfolk. The Commanding Officer of 74 Squadron, Squadron Leader Cooksey was asked to divert and intercept but was unable to follow the target due to lack of fuel. Meteor call-sign Kremlin 34 was scrambled but "the aircraft disappeared out of range to the North of [Neatishead]." [10]

Flt Lt Richards recalled the concern which followed at the Air Ministry and he was ordered to write "a confidential report" on the incident copied to HQ Fighter Command.

"I would assume that the account of the Filter Room picture would have been included in a fuller report from 11 Group which would include similar reports – probably confidential and not included in the ORBs from the GCIs." In summary, Richards said:

Six months later, in July 1947 the FBI agreed to help the USAAF's embryonic study of "flying disks" that would became Project Sign. One of a number of unexplained incidents forwarded to the bureau was a copy of the brief Air Ministry memo concerning the North Sea incident. [12] The Air Ministry case summary stated that: "no explanation has been forthcoming, nor has it been repeated."

This information was not entirely accurate, because a very similar incident had occurred just 24 hours after the North Sea incident. As a direct result, Fighter Command immediately extended its night radar watch. All stations were on alert to watch for the reappearance of "Charlie".

On the afternoon of 17 January two Chain Home Low stations in Lincolnshire (Skendleby and Humberstone) tracked what they described as "an exceptionally good track" (U294) at 10,000 feet above the North Sea. With Eastern Sector on alert, Meteor jets from 245 Squadron were placed on standby to scramble if Charlie came within range, but the plot faded from their screens. At 1945 hours the radar station at Humberstone, near Grimsby again tracked an unidentified target over the sea for a period of 30 minutes at a speed of more than 200 mph. The station log records:

The tension can be measured by an entry that says this was "the longest watch period ever experienced since the termination of hostilities, operational six and a half hours being released at 01.30 hrs".

By the evening, Mosquitoes from 23 Squadron were on "stand by" for the return of Charlie under the control of RAF Neatishead. Situated in the Norfolk Broads, Neatishead is the oldest operational radar station in the world. It began life in 1941 and became a GCI radar station the following year. In his station log, Squadron Leader S. L. Cruwys, reported how on 17 January one mosquito from 23 Squadron had been "scrambled just before midnight to intercept an unidentified high flying aircraft." Cruwys records how an attempt was made to close when contact was made at 18,000 feet but "the observer was unable to hold it as the target was jerking violently". [14] Further contacts were obtained as the target fell rapidly to 2,000 feet, when both the blip and the mosquito disappeared below radar coverage.

'One Mosquito of No. 23 Sqdn, pilot F/L Kent, was at readiness at Wittering to attempt interception of the unidentified aircraft which has been plotted several times lately. At 2040 hrs the Bogey was plotted in WN 6038 [grid square]. The plot was at one time heading south and the Mosquito which had been brought to standby was returned to Readiness, but when the plot again headed into Eastern Sector area the Mosquito was scrambled at 2327 hrs. Although getting within 1-2 miles several times, no interception was made on the target which took violent evasive action. The plot faded at 0015 hrs and after patrolling on a North-South line for some time the aircraft returned to base at 0045 hrs.' [15]

The pilot of the Mosquito was a Sheffield-born World War II night-fighter veteran, William Kent. His log book confirms the incident, with a red ink entry recording an unusual night sortie of 1 hour, 45 minutes – "a scramble interception". In 2001 we were able to trace and interview Kent, who retired from the RAF at the rank of Group Captain.

"I, being one of the very few pilots with any wartime experience and therefore having some understanding of the request, yelled for my navigator and the duty ground crew and leapt off the ground in under four minutes. On a 'scramble' we never listen to any briefings on the ops phone – speed in the air is paramount – and so I had no idea what was brewing until, climbing to height and taken over by the close controller, I was given a brisk brief on the R/T [radio telegraph]. The ORB record is correct except that on reflection with hindsight the unidentified 'aircraft' was almost certainly not an aircraft. It lost height as stated and the airborne radar contact was far more difficult to establish and hold with the aircraft in descent pointing towards the ground. The navigator's screen became swamped with ground returns and the blip was in amongst the cluttered screen, somewhere..." [16]

Kent's encounter with "Charlie" over East Anglia continued for 20 minutes as the ground controller supplied instructions and the navigator tried to capture the object on the Mosquito's radar.

"At no time at any height despite sporadic radar contacts did I sight anything visually, but on a dark night closing on a target at a speed of 10-20 knots [11-23 mph], extreme care is needed to avoid colliding and then only by steering a few degrees off centre does one's night vision show a darker silhouette – often frighteningly close!"

After losing the "blip," the adventure ended and Kent continued to patrol the area without further success. The following day he discussed the incident with the Neatishead fighter controller and a report was sent to the commanding officer of 12 Group. They decided that the "unidentified aircraft" was, most probably, a leaking meteorological balloon. The radar target, if this theory was correct, would have been produced by reflections from metal cannisters as the balloon dropped towards the ground. "The report, which I saw, had no comment except a margin sketch of a pricked balloon," Kent recalled.

Kent's scepticism was typical of the RAF's pragmatic attitude both to the "ghost plane" and, in later years, towards the flying saucer enigma. Nevertheless, the intrusions continued and Charlie appeared again on the night of 23 January whilst three senior officers from the Central Fighter Establishment were visiting RAF Neatishead to control an interception exercise. This was cancelled when "an unidentified high altitude aircraft" appeared on the GCI radar at 28,000 foot. Mosquitoes from 23 Squadron, who in normal circumstances would have been scrambled were unavailable as they were moving to RAF Coltishall. The nearest available aircraft, Mosquitoes of 264 Squadron from RAF Linton-on-Ouse in Yorkshire, were scrambled but before they could reach the Norfolk coast Charlie had faded from the radar screen. [17] During the alert, Eastern Sector turned for help from 74 Squadron's Meteors and Flight Lieutenant Lawrence was scrambled "to intercept an unidentified aircraft out to sea." The 'aircraft' disappeared before an interception was possible and with the weather closing in, Lawrence's Meteor suffered severe icing and was forced to return to Horsham St Faith. [18]

This was the third occasion that unidentified flying objects had been tracked by stations defending England's east coast and the third time that interception attempts had ended in failure. On each occasion the mysterious blips came in over the North Sea towards Norfolk before descending from great height and disappearing beneath radar cover. Concern was mounting and the ORBs record how, as a direct result of the incidents on 23 January, Flying Officer Sewart of HQ Northern Signals Area spent six days at RAF Neatishead on a special mission to investigate the mysterious events. F/O Sewart's assignment was to produce a report "on the unidentified high flying aircraft that have been plotted in recent months." [19]

Sewart's report was completed on 27 January 1947 but is missing from the Public Record Office file where it is listed as an attachment to the station logbook. Summarising its contents, Squadron Leader Cruwys said 'evidence appears to be strong' that the unidentified tracks were caused by radio-sonde balloons released from Downham Market in Norfolk. Downham was a World War Two bomber airfield that was used by the USAAF's 8th Weather Squadron in 1947 for the release of balloons for the study of the upper atmosphere. It can be inferred, in the absence of his original report, that Sewart had matched the release of radio-sondes with Charlie's movements. He may have decided that balloons trapped by turbulent upper-air currents that were developing over southern England had been blown back towards their launch station in Norfolk. Their movements whilst trapped in upper air currents had taken radar operators by surprise and had led to the scramble of aircraft.

However statements made by the Air Ministry, firstly to the Press in April 1947 and again to the USAAF in July, flatly contradict Sewart's conclusions and imply that the Air Staff remained open-minded about the identity of Charlie. Even Group Captain Kent's account of the 'unidentified aircraft' ended with this comment: "I mentioned that a burst met balloon was a possibility, deduced afterwards from its 'behaviour'...but at that time these things [flying saucers] were unheard of and not taken at all seriously." [20]

Other expert opinion attributed the unusual radar blips to freak weather conditions. Operation Charlie coincided with the arrival on 24 January 1947 of a deep cold weather front over southern England, a fact that did not escape attention at the Air Ministry. Before the 1950s, knowledge of the role played by freak weather conditions in the production of "false" echoes nick-named "angels" was in its infancy. Although little understood at the time, the astronomer Dr J. Allen Hynek, who was employed as a consultant to the US Air Force Project Blue Book, believed "atmospheric inversion effects" were the most likely explanation for the English "ghost plane" reports. [21] This explanation is challenged in a technical assessment of the evidence by Martin Shough (see Appendix).

The Air Ministry may have decided it could dismiss the majority of the mysterious blips on its screens as balloons, but in July when the US authorities began to investigate reports of "flying saucers," the RAF continued to list the North Sea incident as "unexplained". Dr Hynek's notes on this case read: "The object observed here was obviously not astronomical. From the information given, it appears that this was definitely an aircraft..." [22] This raises an obvious question: if it was an aircraft, then where was it from?

According to Geoff Easterling the RAF's prime suspect was a Russian intruder aircraft flying from a base in occupied Germany. However, if the speed and performance of the target tracked on 16 January 1947 recalled by David Richards (and apparently confirmed by the contemporary press reports) are correct, this becomes an unlikely proposition. Soviet aircraft were unreliable at long range, and it seems inconceivable that an intruder mission would risk an overflight of UK territory in such a reckless fashion during a period of extreme and unpredictable weather. In addition, Soviet versions of the US B-25 were capable of a maximum speed of 250-300 kts, a figure well within the interception ratio of the RAF Mosquito.

It remains unclear if further unidentified radar blips continued to plague the RAF as the "ghost plane" era moved into the age of the "flying saucer." Entries in the logbooks of radar stations on the south coast of England describe a number of similar incidents during April and May, 1947. One entry from the logbook of RAF Rye, a CH station in Kent, reads: "...the most noteworthy track plotted was an unidentified aircraft which was plotted from 52 miles out to the maximum range of 186 miles." [23]

Group Captain Kent recalls: "I have no other sorties listed in my log books as 'scramble intercepts' such as that of 17 January 1947, but I did fly a few others against 'odd' and 'strange' blips as seen by ground radars in an around East Anglia. I flew at least one in daylight but nothing was seen." [24]

When rumours concerning the panic of January 1947 leaked to the national newspapers in April the Air Ministry decided to deny all knowledge. A spokesman told the Daily Telegraph they were taking no further action. 'We have found no evidence to support the reports at all,' he said. The Yorkshire Post was less inclined to dismiss the mystery completely and its editorial looked at the problem from a different angle:

Radar has plotted some strange things in its time, from children's kites and raindrops to formations of geese. But it surely never plotted a stranger thing than this. What is the aircraft? Speculation takes us into those regions where the scenes are laid for so many thrilling stories in the boys' magazine. Is it a diamond or drug smuggler? Is it conveying a secret agent from one foreign Power to another? In that event it would of course have the secret papers and probably also a beautiful woman spy on board. Is it a guided missile?

The newspaper compared the ghost plane mystery with the reports of phantom German Zeppelins that had circulated before the outbreak of World War I and observed: "It seems to be established that it is only at times of peculiar stress that the public is in the psychological state to receive and circulate such stories." The practical steps to solve the mystery were clear: "Fast RAF fighters must continue trying to intercept the visitor if it should return. Our air service has the fastest fighters in the world and should not find it impossibly difficult – meanwhile we may enjoy the atmosphere of mystery and imagination which surrounds the ghost aircraft." [25]

The most intriguing reference to Operation Charlie is found not in the pages of a newspaper, but in the memoirs of the one-time head of Project Blue Book, Captain Edward Ruppelt. In his book The Report on Unidentified Flying Objects, published in 1956, the retired officer devoted several pages to a description of an intelligence briefing document drawn up by Project Sign staff early in 1948. This was the legendary "Estimate of the Situation" which listed a number of unexplained sightings and concluded that the most probable explanation "was that they [flying saucers] were interplanetary." The estimate travelled upwards to the highest echelons of the US Air Force where the Chief of Staff, General Hoyt S. Vandenberg, batted it back. "The general wouldn't buy interplanetary vehicles [and] the report lacked proof," wrote Ruppelt. "Some months later it was completely declassified and relegated to the incinerator." [26]

Controversy has surrounded the status of the Estimate ever since Ruppelt wrote these words. Not one single copy appears to have survived, and some have suggested it never existed. However, Ruppelt describes reading one copy that had escaped destruction, and he described it as "a rather thick document with a black cover... stamped across the front were the words TOP SECRET." Included in the Estimate was a collection of UFO reports that preceded Kenneth Arnold's sighting of 24 June 1947. The report's authors used these to support their interplanetary theory, arguing that pre-Arnold sightings could not be dismissed as hype or rumour triggered off by media stories. Among the cases used to prove this point were "the English 'ghost airplanes' that had been picked up on radar early in 1947." [27]

This investigation into the British records has established that six months before Kenneth Arnold's sighting, the RAF had logged its first official report of an "unidentified flying object." Furthermore, by July 1947 when the first sightings of "flying saucers" were made in the USA, the Air Ministry remained unable to explain the intruder it had logged in January of that year. This implies that an exchange of intelligence on "unidentified flying objects" between the USA and UK began in 1946-47 with the ghost rocket and ghost planes. Cold War historian Richard Aldrich writes that air power was the cutting-edge of post-war strategy "and it was appropriate that Anglo-American air intelligence was in turn the cutting edge of Western intelligence co-operation." [28]

Air Intelligence files relating to "Operation Charlie" cannot be traced at the Public Record Office or the RAF Air Historical Branch at Bentley Priory. However, documents at the US National Archive show the Air Ministry's Assistant Chief of Air Staff (Intelligence), Air Vice Marshal Sir Thomas Elmhirst, working closely with his opposite number in the US Army Air Force (General George McDonald) during the "ghost rocket" alarm in 1946. Whilst the Swedes were asking the RAF "to take all possible measures to prevent the Americans finding out about Swedish full co-operation in investigating the mysterious missiles," Elmhirst was discreetly passing all intelligence on the subject to McDonald in Washington. [29] Given the level of co-operation that existed between the allies post-war, we can be confident that a dossier on what Ruppelt called "the English ghost planes" (Operation Charlie) would have been shared at the highest level with the Americans when Project Sign was created. What the study contained and concluded remains a mystery.

We wish to thank all those who have assisted this research including Group Captain William Kent, Flight Lieutenant David Richards, Flight Lieutenant Geoff Easterling, Martin Shough, Jan Aldrich, Steven Payne and Mike Hooks of The Aeroplane.