Aircraft call-sign LKX 73 and what is a "gonio buoy"?

[WATU]

Following is from the BdU daily diary (KTB) dated 20 December 1944. The plane is an Allied one over a U-boat. The quote is from an intercept by the German radio listeners. The aircraft is stated to be from 19th Group so RAF Coastal Command. Quite who the interceptors know that I don't know. I cannot see why the aircraft would broadcast that. Could related signals have been picked up from shore to the aircraft from a transmitter known to be 19 Group?

My questions are:
1 From the aircraft call-sign does anyone know details of the plane?
2 What is a gonio buoy? I know what a gonio is - a bearing finding gadget attached to a direction-finder. And I am familiar with expendable sono-buoys. Is it an alternative name for a sono-buoy? Not one I have ever heard used. Seems odd as none of the sono-buoys in use at that time had directional ability. Could be a translation error. I only have the translated version, not the original German one.

​

"plane (LKX 73) reported, "Am over enemy submarine, course 80 degrees, speed 4 knots (position unintelligible), have contact with Gonio buoy.

​

probable submarine location with preparation for attack. Position unintelligible.

​

Am over enemy submarine (position unspecified), course 85 degrees, 2 knots. Have contact with Gonio buoy, first picked up when 4 miles off. Submarine remained submerged so long that no successful attack could be made". Added by BdU - (Direction finder station Husum got a bearing on a plane of 253 degrees at 0657).

 

[Dana Bell]

I don't know the aircraft's identity, but I'll be willing to bet good money that the German listener misheard "sonobouy."

Cheers,



Dana

 

[MIflyer]

Goniometery is the actual real scientific name for radio direction finding (not radar, but using a beacon). So it is possible that is what the Germans meant.

 

[WATU]

I don't know the aircraft's identity, but I'll be willing to bet good money that the German listener misheard "sonobouy."

Cheers,



Dana

I reckon you are right Dana. Interesting that this open chat seems to give the Germans evidence of the use of sono-buoys. I had expected a higher level of secrecy given they would only be dropped around submerged U-boats and thus out of sight. (Much the same as FIDO which had very stringent security rules) Landing by parachute and being passive they would be almost silent.

 

[WATU]

Goniometery is the actual real scientific name for radio direction finding (not radar, but using a beacon). So it is possible that is what the Germans meant.

I don't really think that fits but a good thought. The aircraft is reporting direction and speed of a submerged U-boat. Only sono-buoys and MAD could do that in the opaque Atlantic and the latter was not used by Coastal Command.

 

[GrauGeist]

Sonobuoy ping the sub and report it's results via radio - the sub could certainly hear the pings from the bouy and the RF transmissions from the bouy(s) were on short range VHF or UHF freqs and most likely not encrypted.

 

[fastmongrel]

Sonobuoy ping the sub and report it's results via radio - the sub could certainly hear the pings from the bouy and the RF transmissions from the bouy(s) were on short range VHF or UHF freqs and most likely not encrypted.

Sonobouys didn't ping they were passive hydrophones.

 

[WATU]

Sonobuoy ping the sub and report it's results via radio - the sub could certainly hear the pings from the bouy and the RF transmissions from the bouy(s) were on short range VHF or UHF freqs and most likely not encrypted.

Hi The sonobuoys at this time were passive, silent AN/CRT-1A models. They just had a microphone to listen for U-boat sounds which then transmitted to the circling aircraft, probably the one that dropped the buoys although they could be passed to a replacement aircraft. I have never heard of the Germans doing anything with those transmission which were extremely difficult to interpret even by trained aircrew with a dedicated receiver. The signal was not encrypted, it was just noise.

 

[GrauGeist]

Depends on of it's active or passive - both were used.
The AN/CRT-1 (passive) was the most effective.

 

[WATU]

Coastal Command did not use any active sonobuoys in WW2. The US had the active, directional AN/CRT-4 under development towards the end of the war but I don't believe it was in time to be used operationally even by the US. Happy to be proved wrong but I have looked into it in the past without success.

 

[pbehn]

The Germans used chain home transmissions as a radar detection system themselves, I think this would now be called a passive system, but also fits with the definition of geniometry.
1. An optical instrument for measuring crystal angles, as between crystal faces.
2. A radio receiver and directional antenna used as a system to determine the angular direction of incoming radio signals.

Klein Heidelberg - Wikipedia

 

[strider190]

Following is from the BdU daily diary (KTB) dated 20 December 1944. The plane is an Allied one over a U-boat. The quote is from an intercept by the German radio listeners. The aircraft is stated to be from 19th Group so RAF Coastal Command. Quite who the interceptors know that I don't know. I cannot see why the aircraft would broadcast that. Could related signals have been picked up from shore to the aircraft from a transmitter known to be 19 Group?

My questions are:
1 From the aircraft call-sign does anyone know details of the plane?
2 What is a gonio buoy? I know what a gonio is - a bearing finding gadget attached to a direction-finder. And I am familiar with expendable sono-buoys. Is it an alternative name for a sono-buoy? Not one I have ever heard used. Seems odd as none of the sono-buoys in use at that time had directional ability. Could be a translation error. I only have the translated version, not the original German one.

​

"plane (LKX 73) reported, "Am over enemy submarine, course 80 degrees, speed 4 knots (position unintelligible), have contact with Gonio buoy.

​

probable submarine location with preparation for attack. Position unintelligible.

​

Am over enemy submarine (position unspecified), course 85 degrees, 2 knots. Have contact with Gonio buoy, first picked up when 4 miles off. Submarine remained submerged so long that no successful attack could be made". Added by BdU - (Direction finder station Husum got a bearing on a plane of 253 degrees at 0657).

This is an interesting one. All I have to contribute is negative info. Having studied the submarine war in the Atlantic thoroughly, I have never heard of a gonio buoy. Never read of a sonar or floating sound buoy of any kind being used to hunt U Boats - this was all in the future as was the MAD equipment in the P 3's I used to fly. Maybe they are talking about some kind of floating flare or smoke marker, (these were used in the war). Anyway I'll be interested in reading other posts.

 

[WATU]

This is an interesting one. All I have to contribute is negative info. Having studied the submarine war in the Atlantic thoroughly, I have never heard of a gonio buoy. Never read of a sonar or floating sound buoy of any kind being used to hunt U Boats - this was all in the future as was the MAD equipment in the P 3's I used to fly. Maybe they are talking about some kind of floating flare or smoke marker, (these were used in the war). Anyway I'll be interested in reading other posts.

Hi MAD was used in WW2 albeit it had a horribly short range of only 400 feet or so. It was mainly fitted to Catalinas (nicknamed Madcats) and the best use was to patrol limited shallow waters such as the Straits of Gibraltar. Air-dropped passive sono-buoys were also used and some 150k were made during WW2. Effectively these were little more than prototypes and produced limited results as they were very hard to interpret but they were a step along the road. I can supply more detail on the sono-buoys if you are interested.

 

[WATU]

Managed to answer part of my own question by chance. Hessler's "The U-boat war in the Atlantic 1939-1945" written immediately after the war for the Admiralty mentions a gonio buoy in Vol III para 412. Allied aircraft talking about sono-buoy deployments were overheard and the translation was made as "gonio buoy".