PROFICIENCY & EFFICIENCY 101 WX WATCH 110 AVIONICS 113 DOGFIGHT 114 OWNERSHIP 116 NEVER AGAIN A pulse oximeter measures the amount of oxygen saturation in blood protein by measuring the absorption rate of two different wavelengths of light. Regulator enables four hookups PROFICIENCY Companies offer different flow meters | The air you breathe A distributor and manufacturer help untangle the weeds B Y A LTO N K . M A R S H WADE VERY FAR into the regulations and equipment for providing supplemental and emergency oxygen and you'll find yourself "in the weeds," warns Phoebe Peasley, known as "The Oxygen Lady" at Aviation Oxygen in San Jose, California. Questions to her about whether you need oxygen and what you should buy both end in, "It depends." Peasley acts as weed whacker for confused customers looking for the right purchase. Even the question of regulations is up for debate. As you learned during ground school, pilots flying under Part 91 of the FAA regulations-as most private pilots do-must use supplemental oxygen when flying higher than 12,500 feet for more than 30 minutes. Cylinder holds 2,216 pounds per square inch Cannulas are good to 18,000 feet CHRIS ROSE 98 | AOPA PILOT May 2015