On a summer's day in June 1957, 9 men died when a Swiss Dakota Aircraft crashed without warning into Lake Constance.
On a summer's day in June 1957, 9 men died when a Swiss Dakota Aircraft crashed without warning into Lake Constance. The Swiss Government ordered an immediate enquiry and recovery of the wreckage. A salvage team was headed by Colonel Karl Hoagger. His initial survey revealed so many hazards that underwater television exports from Pye of Cambridge were called in. The only suitable craft available, a local ferry, was unfortunately in continuous daytime service. So it meant salvage by night only.
A Pye underwater television camera arrived. It identified wreckage lying scattered 680 feet below the surface. By early August most had been recovered - but only by laborious, conventional salvage which was adding further damage to wreckage. Vital parts were still missing, too.
And on August 5th, a new and as yet untried piece of equipment makes its appearance - a giant grab attachment for the TV camera. The electric generator is fueled and our story begins.......
As night falls, 2 launches tow the ferry to its search position
The captain, crew and technical men prepare for their long night vigil
The grab is the brainchild of Ben Coleman, a Pye Underwater TV expert, and specially made.
by Pye at the request of Colonel Hoeggar. Everything hinges on its success.
Camera and grab are lowered to within three feet of the lake bed.
The cable is held clear, TV monitors on deck show a continuous underwater picture as the launches and ferry tow the TV camera and grab attachment across the lake bed at 150 feet per minute. If the grab works, wreckage can be identified and salvaged in one operation instead of two. Hours can be cut down to minutes.
The winch operator is the key man ......
....watching the screen with grab poised, judging when to drop it on the moving target.
Everything is recorded photographically.
Somewhere here lies a vital engine, buried in thick mud that swirls up ...... at the slightest touch.
Keeping the speeding grab off the lake bed is a tricky task.
The grab is lifted.....
.. and the water clears again, But the undulating lake bed is not the only ....
..... thing to watch.
A twist in the cable can spin camera and grab like a top and become fouled. Later, a special stabilizing fin....
... makes the cable man's job easier.
What's this. Decisions have to be made quickly.
.. and down dives the grab, steel fingers outstretched.
Colonel Hoeggar signals "up"....
... and the grab is surfaced.
There is much speculation...
... The cable is steadied.
It is wreckage, quite small; a piece of cockpit. It could be valuable evidence. But this is no easy talk.
For night after night, sometimes in torrential rain, the search goes on.
Forward visibility with the TV camera is 20 feet, four times the distance seen with the unaided human eye. But we see nothing.
but acres and acres of mud.
Occasionally tooth marks tell us that other grapnel hooks have been this way before.
Before the was conceived, wreckage had first to be located and marked with a buoy on the surface. Boats then trawled the area with steel hammers, which had to wound round the wreckage before it could be hauled in.
This method often resulted in additional mutilation of the wreckage. On average, it took a whole day to land one piece. The grab it was hoped, would change all this. But after many night of watching, one grows tired.
Attention wanders... the moving pattern of mud becomes a grey, changing background against which to pose one's private thoughts...
And this is the time when something is bound to happen.....
Without warning, a ton of probing steel plummets to the bed of the lake.
False alarm - or a valuable find?
We shall soon know.....
The crew know what to do .....
it is wreckage - large and heavy, and Colonel Hoeggar is determined that this is one that will not get away
It is the wing of the crashed aircraft. Wires are used to secure it.
The cable is held clear.
Holes are made in the wing for the wires to pass through.
It is success! The grab has brought up the complete starboard wing of the Dakota, a very rewarding night's work.
It is dawn and another long night's search is over.
There is still much to be done... The stabilizing fin stands out against the sky.
Equipment has to be dismantled...
Equipment has to be checked and made ready for the next evening's trawl.
The wing is added as an important link in the evidence and Colonel Hoeggar nears the end of an arduous operation which began when he descended to the lake bed by bathyscope to discover almost insurmountable problems. Human visibility less than ten feet, thick and that stirred up whenever the bathyscope touched bottom; and the grave threat of wreckage entanglement. He saw Pye Underwater Television as his only answer.
The equipment which located the crashed Comet off Elba has now gained fresh laurels.
Together we have seen a considerable advance in underwater salvage techniques - the Pye TV Grab - and another step forwards in the endless development of television for which Pye Limited of Cambridge are World famous.