By
Wg Cdr P K Raveendran, ME (Aerospace Engg)
Former Group Director (Flight Test)
National Flight Test Centre, Aeronautical Development Agency,Bangalore

As I was browsing the net- my primary pre-occupation of-late, to kill the lockdown-boredom, I chanced upon an article of which the title read- ‘Gilbert Klopfstein passed away on November 2 , 2006 following a long illness.’ The name- Klopfstein rang a bell and my memory flashed back to early 1979 at EPNER, Istres in France where I had just reported for my Flight Test Engineer course. Among other difficulties characterising the arduous Flight Test training, a primary issue was the medium of instruction- French, for which the training that I managed to get back in India was woefully inadequate. The only saving grace was that I was at EPNER a full three weeks ahead of the scheduled commencement of the course. I remember spending a substantial portion of this lead-time in the library which was well stocked with course material and other flight test related literature, both in printed and audio formats. I found this an effective way to catch up with my French and in the process, get familiar with the course subjects. One such resource that caught my attention was the audio recordings of lectures on a few flight test related topics by one Monsieur Klopfstein. The attributes that impressed me the most were: his depth of knowledge, unorthodox style, eloquent and emphatic delivery. Instantly, I was turning into a fan of his, even before I got to meet this hardcore flight test professional.

Curiosity got better of me and I had started making enquiries about Gilbert Klopfstein. Bits and pieces of information that I managed to get from different sources were interesting to say the least.

A few noticeable things I got to know at that time were:

  • Klopfstein was a genius of sorts, engaged in innovative work in the field of aviation.
  • He did both Flight Test Engineer’s and Test Pilot’s course at EPNER and passed them with flying colours.
  • His first assignment was integration and flight testing of air-air and air to ground missile, Matra- 530, with the French Flight Test Centre, CEV.
  • Very unorthodox, bordering on maverick-like in his approach to his projects that he very passionately engaged in, he was extremely rigid in his views, didactic and at times a bit aggressive, to put it mildly, and therefore difficult to get along with.
  • He and his work were better known in the US than in France.
  • ‘Currently’ in Sup’Aéro, with an aircraft Nord 262, engaged in research and teaching.

None can fault me for yearning to meet my ‘hero’; but the Flight Test Course had other plans to keep me totally occupied- viciously caught up in the daily cyclic routine of – analysis of test data from yesterday’s flight, conduct of today’s flight test and prepare schedule for tomorrow’s exercise- and that goes on till the end of the course which seemed like a mirage….

Somewhere half way through the course, there was a notification saying, next week there would be an evaluation of a new flight guidance system on Nord-262 flying in from Sup’Aéro and I instantly knew what was in store for me. On the d-day, Monsieur Gilbert Klopfstein flew into Istres in his Nord-262 No. 55. We were told that the teams would get a flight each in his aircraft to evaluate a fight guidance system which Klopfstein had conceptualised, designed, developed and integrated on his Nord-262. The flight evaluation exercise was preceded by a briefing to all the teams. I vividly recall his dramatic opening statement in his inimitable style-

Gentlemen, there are two useless instruments in the cockpit; one is the airspeed indicator and the other- the heading indicator (Magnetic compass). “

It was his characteristic metaphoric manner to drive home the fact that angle of attack and velocity vector were more fundamental than air speed and heading. He further went on to explain the flight guidance system using the velocity vector and total energy concepts that he had put in place on his machine which now had the capability to make a safe approach and landing on any runway in all weather and visibility conditions without use of any help from external facilities such as ILS or PAR. He also very proudly stated..

“I have the best Auto-throttle and Autopilot on my aircraft.”

I also have heard that he often spent his own money to buy components required to integrate systems on ‘his aircraft’. Now, what I heard about the enigmatic Mr. Klopfstein started making sense.

After over four decades, I still vividly remember my flight in his legendary Nord-262 No. 55 with Klopfstein on the right seat, u/t Test Pilot in the left and I, on the middle (Flight Engineer’s) seat. On the final approach, the left windscreen blank was drawn to obscure the pilot’s outside view, while he continued flying his approach, following the collimated head-up and head-down cues available to him. On a prompt from Klopfstein, the pilot would throttle back, flare and touchdown. Each u/t TPs got half a dozen approach & landings and invariably every time they would touchdown within five feet of the designated touchdown box and quite naturally they all were amazed over the whole experience. At the time I was unaware of the trials and tribulations that Klopfstein had to endure in the process of bringing his ideas and concepts to fruition and find acceptance in his own country.





Despite the fact that I did have some idea about the resentment that Klopfstein had to face at his workplace (some may say, partly attributable to his own temperament), the article that I cited at the beginning has been truly revealing.

Here are some interesting bits of information and a few hitherto unpublished facts I found out* about Monsieur Gilbert Klopfstein and his travails:
Klopfstein started flying at a very young age; got his Glider licence at 15 and Pilot’s licence at 17.
He left for the US in 1953, where he acquired his first pilot’s stripes, doing flying training as cadet pilot with the USAF at the age of 20.

His eminent and diverse other qualifications include- Alumnus of Sup’Aéro, Sup’Elec and Fighter pilot from Meknes School (Major), Military Air Engineer, Flight Test Engineer cum Test Pilot from EPNER.

At CEV, apart from Matra-530 integration and flight testing, he was also involved in the flight testing of Breguet-941 and Mirage III B.

When the Concorde program was launched, he was assigned an all important task of modifying a Mirage III B No. 225 into a Variable Stability platform as a precursor to design and development of Supersonic Transport aircraft. This was a significant turning point that led to the development of an innovative piloting aid involving use of Velocity vector, Incidence and Total energy concepts.

He also succeeded in a pioneering development of a system to provide collimated piloting cues on head-up as well as head-down displays which were his original concepts. Therefore he was known as the father of Head-up display (HUD) systems.

Fearing mistrust of his colleagues and peers, he had to carry out the tests of his system surreptitiously, which also led to his progressive marginalisation. 

Having mounted the collimator in the cockpit of his test aircraft Mirage, he made a few approaches using his instrument. A ground mechanic monitoring him using a surveyor’s theodolite kept giving him feedback in real-time that he was on the right approach. Overjoyed, he rushed to the squadron and loudly proclaimed to his superiors- ‘ça marche!’ (it works!). They were least impressed and poured cold water over his enthusiasm telling- "you should take a break and go home". This was a moment of immense disappointment for the inventor.

One day when his collimator trials were continuing in Brétigny, the Colonel-in-charge summoned him and ordered to dismantle his ‘infernal material’ as it was never going to work and eventually will end up ‘crashing a plane’. Stung, Gilbert asked him if he would accept God’s judgement. When his superior asked him what he meant by that- “If two most competent bodies in the world in the field of aeronautical research - USAF and MIT Boston - say that my work is worth anything, you will have to let me continue” was his response. “Take the Nord-262 to the USA? You kidding? Besides, she will never cross the Atlantic” said the Colonel. “That I will take care” replied Gilbert. This exchange was a clear indication that he was willing to go to any extent no matter what the consequences were.

The incredible story of how he managed to fly his Nord-262 to the US and demonstrate the system to the US authorities has perhaps never been published before*. Klopfstein was the French correspondent for AGARD, whereby he could officially communicate with his counterparts abroad, especially from the US, bypassing his hierarchical channel. The American representatives were interested in the revolutionary piloting aid that he developed and a demonstration was scheduled in the US. For fear of seeing the project fail, Klopfstein did not immediately disclose this to his superiors, while he decided to wait for an opportune moment.

And that moment finally came on the 25th of April 1972 in the form of a flight test campaign of SAGEM’s Inertial Navigation system on Nord-262. The test profile involved long flights along the meridians and parallels for which
Gilbert himself prepared the ‘test orders’ so that he could wait till the last moment before informing the details of the tests planned to his hierarchy. He then took a friendly colleague into confidence and left a sealed envelope with him with instructions to deliver it to the Commandant of CEV on explicit clearance from him. Accompanied by a couple of technicians, he finally set course along the meridian 5 deg West till west of Scotland. At the scheduled time, the aircraft did not turn around and instead proceeded on a North-West heading. At that precise moment the test order got delivered to the office of his boss. Recalling the aircraft would have exposed him to an embarrassment besides uncomfortable diplomatic issues between the two countries. Suffice it to say that he could not recall Gilbert, who proceeded on his mission regardless. With ready intervention and help from his US counterparts at AGARD, Gilbert was able to make a safe landing at Sondestrom in Greenland with only 10 minutes fuel in the tanks. Further flight to Washington via Frobisher, Goose Bay and Loring was uneventful. In the US, he made a series of presentations to FAA, the National Aeronautical Facilities Experimental Centre, USAF, Boeing, Lockheed, Douglas, Eastern Airlines, MIT, the Flight Research Dept of the Cornell Laboratory and a representative from ALPA.

As the date of his return to France approached, Klopfstein started getting worried about the consequences of his actions. When he shared his concerns with an American pilot, the latter gave him a pre-print of USAF report on his system as a testimony to its usefulness and efficacy. On 29th September when he landed in Brétigny, the chief was waiting for him with a contingent of military police to arrest him. As he got off the plane, his boss asked him what he had to say. In response, Gilbert handed him the USAF report and started walking away putting up a brave face even as he was trying to conceal his fear. Suffice it to say, the military police did not receive order to arrest him. From then on, he was relieved of his research responsibilities.; however he could continue academic flight research at Sup’Aero and demonstrate flight mechanical aspects to the students.

n 1976, Klopfstein received a phone call from Jean Coureau, Chief Test Pilot of Marcel Dassault, who four years back did not grant an appointment to meet him. Coureau wanted to make a flight, equipped with the Collimator. After several flights, Jean Coureau published a report recommending Dassault aeroplanes be fitted with his system; more or less on the lines of USAF and MIT reports that recommended equipping American planes with systems based on concepts presented by Klopfstein. Since then all American military planes and space shuttles were equipped with piloting collimators based on what Americans very officially started calling “Klopfstein Display”. With advances in digital technology, Gilbert was able to successfully upgrade his system by linking his head-up cues with symbolic representation of the outside world in the form of a synthetic runway which was known as ‘Klopstein Runway’.
In 1982, Gilbert was invited by the US Air Force to fly their brand new F-18 fitted with his piloting Collimator. His hierarchy would accept the invitation with the condition that an officer of the seniority of a General Staff would
accompany him, which was not acceptable to the Americans. However they left the invite open. A few weeks later during his holidays, Gilbert flew to Los Angeles, where a waiting official vehicle took him to Edwards Air Force Base, where he attended a briefing followed by a 45 minutes flight in the new single seater aeroplane of the U S Air Force, all at the age of 49. On return to France, he continued flying at Sup’Aero without disclosing his flight in F-18 at Edwards Air Fore Base.

Two months later the General who had refused his authorisation to go to US, made an enquiry with his American counterpart to check if the invitation was still open. When he was told that the Chief Engineer Klopfstein had already come and flown the aircraft, he immediately summoned Klopfstein and sought his explanation; and consequently Klopfstein was forced to resign from all his military functions and from the CEV.

In his seventies, Gilbert Klopfstein was living a lonely, destitute life in southern France, with his cat to company. He was drawing only a meagre pension as a retired military pilot, thanks to a malicious official who expunged 500 hours of operational flying from his logbook citing disciplinary reasons. As a service personnel he couldn’t claim any patent nor monitory benefits for his inventions. To add to his woes, his health condition too had deteriorated as his immune system had suffered some damage from exposure to radiation while he was engaged in integration and flight testing of nuclear stores on Mirage earlier on; and he was on heavy life-long medication. And alas, the maverick genius breathed his last on 2nd November 2006. All this while, aeroplanes all over the world, including Space shuttles, Dassault fighters, Business Jets (Falcon Series) and Airbus A-380 were operating with flight guidance system incorporating Klopfstein Display and Klopfstein Runway. What an irony!

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