Room to Breathe

Mark Twain wrote, “The air up there in the clouds is very pure and fine, bracing and delicious. And why shouldn't it be?--it is the same the angels breathe.”

For all its beauty and truth, we also know that at FL250, our time of useful consciousness is a mere 3 to 6 minutes. Hence, there are regulations about oxygen... requirements for quantity, duration, training, etc.

GENERAL

CAR 605.31 Oxygen Equipment and Supply

• non-pressurized aircraft 
• if more than 30 minutes between 10 000 and 13 000 >> all crew and 10% of passengers (at least 1 passenger) 
• above 13 000 >> all persons (for at least 1 hour if air transport) 
• pressurized aircraft following emergency descent 
• similar, but a bit more complicated, see table in regulations 

CAR 605.32 Use of Oxygen

1. Where an aircraft is operated at cabin-pressure-altitudes above 10,000 feet ASL but not exceeding 13,000 feet ASL, each crew member shall wear an oxygen mask and use supplemental oxygen for any part of the flight at those altitudes that is more than 30 minutes in duration. 
2. Where an aircraft is operated at cabin-pressure-altitudes above 13,000 feet ASL, each person on board the aircraft shall wear an oxygen mask and use supplemental oxygen for the duration of the flight at those altitudes. 
3. The pilot at the flight controls of an aircraft shall use an oxygen mask if

• the aircraft is not equipped with quick-donning oxygen masks and is operated at or above FL250; or
• the aircraft is equipped with quick-donning oxygen masks and is operated above FL410.

FIRST AID OXYGEN

CAR 704.67 (Commuter): if flying above FL250 >> supply one passenger for one hour

CAR 705.72 (Airline): 2% of occupants (at least 1 person) for one hour


PORTABLE OXYGEN

CAR 705.94 (Airline): above FL250 >> 15 min supply for each FA

Do you know what might happen if you don't use oxygen when your body requires it?Everyone reacts to hypoxia differently.  I went to the FAA Civil Aero Medical Institute in Oklahoma City for some invaluable High Altitude Training.  

Section 24 of Standard 724.115 and Section 29 of Standard 725.124 both specify that 'High Altitude Training is required for all flight crew members operating aeroplanes above 13 000 ASL before first assignment on a pressurized aeroplane and every three years thereafter.'