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Fifty Thousand Feet

by Captain (ret'd) Turbo Tarling
Originally printed in The Courier – 29 April 1987


The CF-100 Mark 5 had remarkable climb performance, with an initial climb rate of 9–10,000 feet per minute.  The vertical speed indicator pointer would remain hard-fast against the stops at 6,000 feet per minute until the aircraft was approaching 25,000 feet.  Only then would it slowly begin to register the exact rate of climb.


With its extended wings, and low wing-loading, the Mark 5 was very much at home at high altitude.  Our day-to-day missions were normally flown between 40-45,000 feet and the aircraft performed beautifully.  We were all tempted to see how high it would go but regulations, and common sense, restricted us to a maximum of 45,000 feet without pressure suits.


With a pressure differential of 3.5 psi we would have a comfortable cabin altitude of 24,000 feet while we were flying at 45,000 feet and we simply snugged up our oxygen masks a bit.


The Aircraft Operating Instructions listed the procedures to follow in the event that cockpit pressurization was lost at high altitude and issued the following warning, “If the mask is not tight, conscious time at 48,000 feet cockpit altitude is approximately 15 seconds.  With a perfectly fitted mask, the conscious time is approximately 10 minutes.”


A cabin pressure warning light in the cockpit would come on at 31,000 feet, plus or minus 1800 feet, and at 33,000 feet cockpit altitude the oxygen system would switch to pressure breathing, forcing 100 percent oxygen into our masks, under pressure.  We had all experienced pressure breathing while training in the decompression chamber and it was very fatiguing – five minutes was plenty for most of us.


It was obvious, by the summer of 1958, that aircrew flying the new CF-105 Arrow would require better equipment than we were using in the CF-100.  Until the Arrow came into service, the CF-100 would be progressively pushed to its limits.  To satisfy both requirements, the RCAF developed two new pieces of equipment; a partial-pressure vest and the Pate-suspension for the oxygen masks.


In September 1958, the equipment was ready for testing and volunteers were requested from my squadron.  My navigator, F/L Doug Williams and I (F/O Turbo Tarling) were one of the crews selected from the volunteers,  On September 29, we were flown from Uplands to RCAF Station Downsview in Toronto and spent the next two days at the Institute of Aviation Medicine being briefed, getting our Pate-suspensions installed and our vests fitted.  The vests were form fitted by adjustable cords at the back and were worn over our flying suits.


On October 1, we paused momentarily at 27,000 feet in the chamber to make a final check of our equipment, and then we were explosively decompressed to 50,000 feet, to simulate a canopy loss.  The vest and Pate worked perfectly – without them we would have been in an “emergency” situation.


With our new equipment we were now authorized to conduct high altitude flights above 45,000 feet to further test the equipment and to develop suitable intercept tactics at these new heights.  On October 6, Doug and I took CF-100 #500 up to 50,000 feet.  With a full fuel load of 8500 pounds it would only climb to 46,500 feet initially, but after we burned off some fuel it easily reached 50,000 feet.


We made a total of six flights in the next nine days, recording as much data as possible.  We observed that:  the CF-100 could fight at 50,000 feet but it had to be flown with care – with an indicated speed of 168 knots there was little margin between the stall and the limiting speed of Mach .82; 20 degrees of bank was the maximum that could be sustained without loss of speed or height; the autopilot gave the best results; and the aircraft could be glided 150 nautical miles at idle power.


At the end of each mission we would throttle back to idle and set up a precision glide with the autopilot, starting at 155 knots indicated and gradually increasing to 175 knots.  As soon as power was reduced the cabin altitude would rapidly increase, as expected.


At 31,000 feet cabin altitude the cabin pressure warning light would come on, and at 33,000 feet pressure breathing would begin, but this time with a difference.  The partial-pressure vest/Pate-suspension combination made it all seem very routine.


One problem we couldn’t avoid, however, was “the bends” – throbbing and painful aching in the elbows and knees – caused by nitrogen bubbles which formed because of the high cabin altitude.  We had to grin and bear it during the long descent back to base – rubbing just made it worse.  The pain would be gone in an hour or so, anyway.


Doug had the worst of it since he had to keep notes during the descent and writing was painful when you had the bends.  All I had to do was make minor adjustments to the autopilot.


The data that was compiled on these high altitude flights was dutifully collected and filed somewhere. The Arrow was subsequently cancelled; the CF-100 stayed at 45,000 feet, and the excellent partial-pressure vest was shelved. The Pate-suspension, however, is still standard issue some 28 years later.


Captain (ret’d) Turbo Tarling


F/O Turbo Tarling

CF-100 Mk5

428 AW (F) ‘Ghost’ Sqn

Fall 1959

Turbo is wearing the Pate-suspension.

F/O Bob Walker and F/O Turbo Tarling

Turbo is wearing the new O2 Partial-Pressure vest.
Note the oxygen hose connection is on the right side of the vest

F/O Bob Walker became a "Friendly Ghost" for a day
First trip in a CF-100, #496, for a wedding flypast
Saturday 4 October 1958