Blenheim Pilots Interception Log, Aug (part) 1940

Ian

A member of the Royal Air Force Historical Society tells me that he read a book on the work of the Interception Unit many years ago but couldn’t remember its name.

I did a search and came up with this

‘Night Intruder’ by Jeremy Howard Williams
it describes the book as:

a personal account of the radar war between the RAF and Luftwaffe nightfighter forces.

Subject: Great Britain. Royal Air Force. Fighter Interception Development Squadron

Subject: World War 2. Air operations by Great Britain.. Royal Air Force. Fighter Interception Development Squadron

From the description it appears to be about the ‘Fighter Interception Unit’ Squadron and he seems to think it is the book to which he was referring to.

Have you got it and does it cover 1940 and mention about any particular aircraft interceptions over the channel please?

Mark

Thanks Ian and Papa Lima

That book by Watson Watt sounds interesting, at this rate I shall have to build an extension to house the growing book collection, its such a fascinating subject I would like to know more about.

I agree Ian, R.V. Jones book is more on the side of discovering what the Germans were up to!

Mark

By strange coincidence, mine is also an ex-library copy, bought for 2 shillings (that shows how long ago it was!).

Mark,

I do have both Most Secret War and Laurie Brettingham’s book, Beam Benders. R V Jones’ book is interesting although it deals with scientific intelligence and thus is more about German developments than British ones. I have other publications which provide more detail on German radar work, but Jones’ book is a good read.

Laurie Brettingham’s 80 Wing book, Beam Benders, is excellent and he’s also written a book about 100 Group, Even When the Sparrows are Walking, which is also very good.

I knew about the advert to get people to claim their logbooks, and that the PRO does hold some examples. I just didn’t realise they had F/O Ashfield’s which, as you say, is a very interesting example.

Papa Lima,

Thanks for your offer but I do indeed have a copy of Three Steps to Victory, which is in fact an ex-library copy bought for £1.50. I’ve seen it available on the web for close on £100! The book is not an easy read, written as it is in a style very like Watson-Watt’s way of speaking – he would never use one word when a dozen would do!

Ian, no doubt you have a copy of “Three Steps to Victory”, the entire story of early radar, including AI, by Sir Robert Watson-Watt, Odhams Press 1957. If not, I could lend you my copy.

Ian

Pilots Log Books and other Logs went into storage once completed or when the person was released from RAF Service, after the War was over. Then a newspaper advertisement was placed in the National Press about 1960 apparently and you could claim your own personal Log Book.

Some were claimed by RAF Personnel and next of kin, but a lot were scrapped, before the RAF Museum at Hendon came into being. However, the Public Record Office did retain a few as a representative cross section of the various Units etc.

Glynn Ashfield’s was retained and it is interesting as he was one of those involved in a lot of the early interception work, trials, tests and calibration of the early A.I. sets, equipment and R.D.F., with G. Ashfield being repeatedly mentioned in the F.I.U. O.R.B. Form 540 (Tangmere).

An interesting book is ‘Most Secret War’ written by the War-time British Intelligence Radio Scientist R.V. Jones (originally copyrighted 1978) which was reprinted by Wordsworth Editions Ltd in 1998 and still available several months ago when I got a new paperback one. It has 556 pages, dealing mainly with Scientific Radio Intelligence, countermeasures, radio navigation, navigational beams and Radar development. Right up your street I would of thought, some of it is out of my league.

Also No 80 (Signals) Wing by Laurie Brettingham which I expect you have got, about the Radio Countermeasures (R.C.M.) bending the German Navigational Beams. By the way, their Operational Record Book Form 540 still exists and was known as the Blind Approach Training and Development Unit (B.A.T. & D.U.), based at Boscombe Down in August 1940. Their aircraft could fly apparently without having to notify Controllers of their flight movements and they were searching the skies for the German Navigational Beams, like X-Gerat. But you will know all that I expect.

Several years back I acquired a photocopy of a (Telecommunications Research Establishment) T.R.E. scientific Report into a crashed German Heinkel in January 1941 near Eastleigh which they think was equipped to fly by beam, (crashed only a few fields away from the field where my Grandfathers Whitley crashed). Despite the Heinkel being badly destroyed, the wireless Operator had managed to get out, unfortunately too late for him, but his notebook survived and its in this T.R.E. Report that he had been beam flying previously and was likely flying by beam on this fateful Op.

I got the books for reference only and I have not studied them deeply. My interest began in this when I began investigating our bomber aircraft signalling procedures when they returned from Ops abroad and approached the British Coast.

Regards

Mark

Mark,

Thanks very much for those extremely interesting posts. I’ve never looked at FIU material in the PRO and certainly wasn’t aware that they had F/O Ashfield’s logbook, so thanks very much for letting me know about it!

2nd adjacent part of the F.I.U. Tangmere O.R.B. page.

F.I.U. Tangmere

Ian

As promised

Crown Copyright National Archives AIR 29/27

Ian

The part in commas is a direct quote from the Fighter Interecption Unit Operations Record Book 22.7.40, regarding Poling.

Quote
“That night Flying Officer G. Ashfield shot down a Dornier 17. The Commanding Officer controlled him from the Tangmere Sector Operations Room, on data supplied by R.D.F. Station Poling. Pilot Officer G.E. Morris, Observer, first saw and recognised the enemy aircraft. Sergeant R.H. Leyland, A.I. Operator, gave the A.I. directions.”
End of Quote.

Poling obviously picked up the aircraft (Dornier) on radar and fed the position by telephone to the Commanding Officer (Controller) at the Tangmere Sector Ops Room. Next the Controller had to vector the Blenheim to somewhere near the Dornier, so that the Blenheim could attempt an interception with his A.I. set. It seems that the Observer might have had the Dornier sighted visually already and used the A.I. to keep it in sight as the Dornier probably tried to evade the Blenheim.

But I think this is what we are both trying to say.

Sometimes, even when vectored to the area by the Controller, they were not always able to locate the aircraft that they were intending to intercept, visually or when using A.I.

See next 2 posts, due to size of the photocopy I cannot scan it, so I hope several photos (reduced) will suffice.

Regarding the Page of the Pilots Log on the original post is that of G. Ashfield and is held at The National Archives in AIR 4/2.

Regards Mark

Mark,

May I ask whose log book the extract comes from? Just curiosity really. If you’d rather not post a name, would it be possible to PM me the details?

Mark,

Sorry to be an absolutely pedantic b*****d, but Poling wasn’t able to put the Blenheim within AI range. The pick-up range of AI Mk III was much less than the range at which CH could differentiate between two targets. Strickly speaking, Poling put Ashfield and Morris in the general area of the Dornier and they were fortunate enough to close-in and pick it up on AI. The use of Poling for direct ground control was an experiment which proved the general concept but demonstrated that a more accurate ground radar was required. This led to the introduction of GCI (Ground Control of Interception) with the fighter being directed from a PPI tube showing a plan of the relative positions of the fighter and target, allowing the controller to vector the fighter direct from the radar screen.

I’m sure you knew all this anyway, but as I said I’m the world’s worst pedant!

Allan
Re Waggling your wings in your reply.

In Air Publication A.P. 1795 (February 1940) ‘SIGNAL BOOK for use in Air Navigation’ Chapter IV, ‘Visual Signals To Be Made by Aircraft (Coding).

‘Section III. – Signals made by an aircraft in flight in reply to signals made by an aircraft which has been forced to land’

It says:

“(These signals, which are not prescribed by the Air Convention of 1919, are given here by way of example.)”

“2. That it does not understand the signal, by rocking from side to side.”

Obviously a rocking movement, or waggling of the wings could be used for signalling, in the Signal Book example (which was given as an example) it applied to signalling to the ground.

Unfortunately, I only have about a quarter of the Signal Book photocopied, so it may have applied in other signalling areas too, as your book seems to suggest.

If he didn’t understand, I expect he would be challenged or signalled to again for his ‘colour of day’.

I have a copy memo of 1941 regarding 2 friendly aircraft being shot down together by our fighters in Scotland and the memo said that the Challenge and Reply procedure was flawed, because if the aircraft failed to reply, it would likely be shot down.

In 1940 the bomber aircraft being challenged would fire its ‘colour of day’ (usually a 2 colour cartridge from a Verey pistol), or if near a UK Defended/Prohibited Area, the ‘letter of the period’.

Regarding Navigation Lights, according to an August 1940 Court of Inquiry bomber aircraft could only show their navigation lights at less than 2,000 feet over the land. (Navigation Lights were extinguished when over the sea areas). Apparently, the Battle on this occasion was showing his navigation lights above 2,000 feet and more than 5 miles from his aerodrome, so they were shot down and 3 killed only a few minutes into their sortie, despite firing their colour of day. Apparently the intercepting Pilot and Controller say they did not know the existance of the Operational Bomber Station and that aircraft were on Ops from it that night.

Another August 1940 C of I regarding an aircraft KNOWN to be a Whitley (from 10 OTU) was shot down on 5th August 1940 by Fighters from Silloth, but managed a forced landing at Squires Gate Aerodrome.

A Memo in a file at the National Archives, Kew indicated that our Bomber Pilots feared our own A.A. and defensive fire more than German A.A.

Interesting observation from your Book, Allan.
Thanks
Mark

Ian
You are absolutely correct, Airborne Interception Sets could not distinguish between friend or foe. I have a copy of a memo from about Aug 1940 regarding A.I. which states this.

As you say, it was up to the Pilot to make a visual identification and there are a number of references in various documents, continually reminding Pilots of the need to exercise great care and placing the onus on them to visually identify correctly and decide whether to open fire or not, with references to the rules on challenge and reply.

Regarding the Dornier 17 you mention, the F.I.U. O.R.B. (Tangmere) for 22.7.40 says:
“That night Flying Officer G. Ashfield shot down a Dornier 17. The Commanding Officer controlled him from the Tangmere Sector Operations Room, on data supplied by R.D.F. Station Poling. Pilot Officer G.E. Morris, Observer, first saw and recognised the enemy aircraft. Sergeant R.H. Leyland, A.I. Operator, gave the A.I. directions.”

23.7.40
“Some A.I. tests were made by day, and at night the final trials of the flourescent sight.”

The example you mention is interesting, the ground controller would vector the Blenheim within A.I. range of the aircraft he wanted him to intercept (based on info from the R.D.F. Station). The Blenheim would search using his A.I. when in A.I. range and then make a visual interception/identification close up.

All interesting stuff!!
Thanks for your reply.

Mark

Just as an aside – the Blenheim was the first aircraft to carry out an interception using airborne radar, on the night of 22/23 July 1940 when a Blenheim Mk I from the Fighter Interception Unit shot down a Dorner Do17.

Just to be absolutely pedantic, Observer, the AI could never tell freidn from foe but could only detect an oject. It was the function of the IFF equipment to tell friend from foe. However, fighters could not trigger the IFF transponder in targets, so had no way of telling if it was friendly or not. The only way to do this was from information provided from ground radar, which was not always accurate in identifications (since not all friendly aircraft were fitted with IFF) and by visual examination. Night fighters had to close to visual range not only to be able to attack the target but also to be able to visually identify it as friend or foe.

Incidentally, a very interesting Pilot’s Log extract!