Final answer:
Class A airspace in Canada starts at 18,000 feet (FL180) and requires aircraft to operate under IFR, with ATC regulating distances similar to electron orbits in quantum mechanics.
Step-by-step explanation:
In Canada, Class A airspace begins at 18,000 feet (FL180) above mean sea level (MSL) and extends upwards to FL600 (60,000 feet). Aircraft operating in this airspace must be under Instrument Flight Rules (IFR), ensuring they are separated by Air Traffic Control (ATC) and are following a filed flight plan with current weather conditions and air traffic considerations taken into account. The specific altitude where Class A airspace begins can vary in different countries, but the principle is consistent—aircraft are operated under strict regulations to maintain a safe distance from one another. ATC regulates air traffic by assigning different flight levels and routing to avoid collisions, similar to how electrons have discrete orbits in quantum mechanics.