10-22-93 23:55 OTTO RENTSCH

FACSIMILE TRANSMISSION

FROM: OTTO RENTSCH

AVIATION CONSULTANT/SAFETY ADVISOR

FUCHSENBURG 25, 8640 RAPPERSWIL

SWITZERLAND

PHONE/FAX NO: 0041 55 27 62 36

NO. OF PAGES: 2

DATE: October 22, 1993

TO: Bertil Werjefelt, President Visionsafe Corporation

Fax (808) 247-6313

Dear Bertil,

You have asked me to formally answer the question, "Has the record shown that heavy, dense and continuous smoke has caused the loss of otherwise flyable commercial aircraft?" The answer is "Yes". In fact, it is probably relatively common knowledge in the Aviation Safety and Accident Investigation Sectors of the industry,

As you know, I recently retired as Head of Safety for Swissair, after working for the company for 40 years. I am now an international aviation consultant on safety matters and am still very much involved in aviation safety activities world-wide.

As we are both well aware, Swissair lost a CV 990 on the 21st February 1970 just outside of Zurich. There were 47 fatalities. This is one of the so-called classic accidents, where loss of pilot vision because of dense continuous smoke in the cockpit led to loss of control of the aircraft and the crash. This is well documented in the accident record as well as the recorded conversations between the aircraft and the controllers on the ground. The record clearly shows the aircraft was flyable but ultimately crashed because the pilots couldn't see their flight instruments, which are so critical to maintaining safe flight.

This accident and other cockpit smoke incidents prompted me to encourage Swissair to remedy this safety problem when we learned there was a solution (EVAS). As I recall, many Swissair staff were involved in the testing and evaluation of EVAS, which took about two years. I personally attended several simulator tests where the cockpit was filled with very dense smoke and witnessed our pilots, as well as SAS pilots, accomplishing successful landings, which would have been impossible without EVAS.

I know that it was a decision of Swissair to acquire EVAS for all its aircraft and that SAS was also going to do so, beginning with its 767 fleet. I an also aware that Swissair and SAS have put the actual implementation of EVAS in temporary abeyance. I suspect, to some degree, the recent economic hardships and restructuring of the airline to merge with others may be part of the reason. We were just reminded of the need to correct this serious safety problem as soon as possible. Last week a Swissair MD-81 made an emergency landing at Munich airport due to extreme smoke in the cockpit. The smoke was caused by an electrical cable bundle on fire in the cockpit.

The situation was so serious that the pilots ware unable to read the approach chart and the instruments. For example, the speed indication was estimated according to an approximate position of the needle. The Approach Center personnel had to provide assistance to the pilots on frequencies and directions. This level of safety is unquestionably unacceptable. Pilots must be able to see so they can safely control and land their aircraft.

Having talked to the Chief of Accident investigation at the Swiss Department of Transportation, it clear that skilful piloting and lots of luck was the only difference between the successful emergency landing, versus a catastrophe. A very slight increase in smoke intensity would probably have totally blinded the pilots and might have changed the outcome. (There were 98 passengers and 7 crew on board). The need to ensure pilot vision in such emergencies is very clear. Hopefully the Authorities (and the Airlines) will now act quickly.

Also, if my memory serves me right, the American NTSB issued a safety recommendation about 10 years ago in connection with a DC-9 (or MD 80/81?) smoke accident in Cincinnati where there was the same type of situation with severe smoke in the cockpit and the pilots had serious difficulties seeing their instruments. (There was also a similar one in Norway 4 or 5 years ago with a DC-9 or MD-80). In spite of the NTSB recommendation it is obvious that the safety problem still persists.

With further regard to your original question, I am also aware that there have been several other fatal smoke accidents world-wide, many of which the Authorities know and/or suspect were caused by loss of pilot vision. However, to my knowledge, few, if any, are as well documented at the Swissair accident of 1970.

I trust the foregoing answers your question.

Very truly yours

Otto Rentsch