The entire episode produced two contradictory emotions in the aviation world. One was deep concern over how simple errors, this time in a switch to the metric system with the introduction of the Boeing 767, could come so close to producing a major disaster. The other was admiration at the skill of the pilots, whatever their role in the original errors, in putting the huge wide-body craft down safely when, without power, they would have no chance to make second landing approoach.

One highly respected industry pilot in this country who asked not to be identified said: ''The captain may get the book thrown at him for taking off with too little fuel. But when the time came, he was there.''

The carrier said that fuel had been measured manually with special ''drip sticks'' because the electronic gauging system aboard the plane, Air Canada's first metric aircraft, was not working properly. But in converting the fuel volume determined from the stick readings into total fuel weight, the wrong conversion factors were used. The net result was that the pilots apparently thought the figure for fuel weight on board was in kilograms when it was really pounds. Since one kilogram equals 2.2 pounds, the plane took off with about half the fuel that it should have had. Use of Fuel for Flights

Normally, airplanes do not take any more fuel than is needed to complete a flight and still have a safety margin. To carry more fuel involves unnecessary weight and hence raises consumption of costly fuel.

Errors were made not only before the day's initial takeoff from Montreal but also before the takeoff from Ottawa, an interim stop. The problems with the on-board fuel-gauge system not only denied the pilots an automatic check on the fuel load but also meant that the crew did not receive the warning normally given by amber lights half an hour before fuel will run out. The plane was cruising at an altitude of 41,000 feet when the engines abruptly started losing power.