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Oxygen Requirements at Altitude

The FAA requires that all pilots flying their aircraft above 12,500 feet for 30 minutes or longer, or upwards of 14,000 feet during the entire flight, must use supplemental oxygen. The amount required is 1 liter of oxygen per minute for every 10,000 feet. For example, at 18,000 feet there should be a flow of 1.8 liters per minute of oxygen available via a standard breathing device. The FAA requires that there is a device so attached to each breathing device that visually shows the flow of oxygen (Nelson flow meters meet this FAA requirement). The FAA also regulates that passengers must have supplemental oxygen available over 15,000 feet. It is recommended that supplemental oxygen be used at night at altitudes over 5,000 feet.

Effective Performance Time

This is the amount of time during which a pilot is able to effectively or adequately fly his aircraft with an insufficient supply of oxygen. At altitudes below 30,000 feet this time may differ considerably from the time of total consciousness (the time it takes to pass out). Above 35,000 feet the times become shorter and eventually coincides with the time it takes for blood to circulate from the lungs to the head.

Cannulas

The cannula type breathing devices can be used up to 18,000 feet. If a cannula is used, there must be a standby facemask available for each cannula in case of a head cold or congestion. Pilots should refer to FAR 23.1447 to see if any restrictions apply for their use of cannula type breathing devices in operating their aircraft.

Average Effective Performance Time for flying personnel without supplemental oxygen			Factors which will determine the Effective Performance Time Altitude
15,000 to 18,000 feet	30 minutes or more		1. Altitude. EPT decreases at high altitudes.
22,000 feet	5 to 10 minutes		2. Rate of ascent. In general, the faster the rate, the shorter the EPT
25,000 feet	3 to 5 minutes
28,000 feet	2 1/2 to 3 minutes		3. Physical Activity. Exercise decreases EPT considerably.
30,000 feet	1 to 2 minutes
35,000 feet	30 to 60 seconds		4. Day-to-day Factors. Physical fitness and other factors (smoking, health, and stress) may change your ability to tolerate hypoxia from day to day, thereby changing your EPT.
40,000 feet	15 to 20 seconds
45,000 feet	9 to 15 seconds

Cylinders

Oxygen cylinders should be hydrostatically tested every 5 years. Steel Cylinders are usually tested every 10 years. Specially constructed oxygen cylinders could have a shorter period for hydrostatic testing. There could also be a limit on how long the cylinder may be used when it was supplied originally as a factory installed, built in oxygen system. Most cylinders can be used indefinitely, however some aircraft may be required to replace the cylinders after 25 years. Factory supplied built in oxygen systems will have the necessary maintenance information in the aircraft manual.

Around the neck of the cylinder are letters and numbers stamped into the cylinder. Of importance to the pilot are three items. At the beginning of the numbers are the letters, DOT. This indicates that the cylinder has been approved by the Department of Transportation, which means they can be commercially filled. European cylinders may not have the DOT stamped on the cylinder. This could prevent the cylinder from being refilled in the USA. Owners of imported aircraft from Europe should be aware of this problem.

After the DOT label, there will be 4 numbers. These indicate the rate cylinder pressure. 2015 and 2216 are common.

After the end of all the numbers will be two numbers followed by a letter that looks like an inverted capital A, then two more numbers. This is the date of manufacture of the cylinder. The first numbers are the month (03 for example would be March) and the last two being the year of manufacture (96 would be for 1996).

The date testing is required is based on this date, not when the cylinder was purchased. It is quite common to have an unused cylinder that could be one or two years old. The cylinder will still have to be tested 5 years after the date stamped on the cylinder.

Outlets in Built-InSystems

We understand that some systems require the O-Ring seals in the manifold outlets to be replaced on a scheduled basis. Consult your aircraft manual for more information.

FAA Altitude Test Chamber

We strongly recommend that anyone who uses or plans to use oxygen in aircraft attend one of the physiological training programs sponsored by the FAA and the military. Courses include information on hypoxia and hyperventilation, as well as offering altitude-chamber rides where you can safely experience your own reaction to oxygen deprivation. There is a waiting list for the courses. The cost for the courses is minimal. Courses are offered at many military bases around the country. You can get an application form by writing or calling the FAA Civil Aeromedical Institute, Airman Education Section AAM-420, P.O. Box 25082, Oklahoma City, Okla. 73125, (405) 686-4837. Better yet, contact your local FAA Accident Prevention Specialist and ask for AC Form 3150-7.

One of our customers who recently attended one of these courses said that the instructor warned against the excessive use of lipstick and Chapstick type material on lips when using oxygen. He also said that you should not eat peanuts during the use of oxygen. In both cases, the excess oil along with ignition by a static electricity charge could cause a potential reaction with oxygen.