“Today, we will focus on pressurization issues forcing an emergency descent. You can hand-fly the procedure or let the autopilot assist with the EDM (emergency descent mode).” My wonderful instructor at FlightSafety, Dax Beal, had me prepared for the ritual.
But in real life, a true pressurization emergency will not happen exactly how you trained for it.
Some real-life examples:
Over Cape Girardeau, MO, at FL 270 in a B200 King Air, the captain left the cockpit to retrieve something in the cabin. Before he could return, the outer pane of the windshield cracked with a loud thud. The pilot returned to the cockpit and decided to de-pressurize the cabin even though the checklist said to maintain pressure, and that the aircraft could be flown up to 25 hours after such an event. Both pilots in the front seats tried to don their oxygen masks but received no O2. The captain had turned off the system to save it for another flight.
Within a few seconds, they both passed out. For the next seven minutes, the CVR (cockpit voice recorder) recorded sounds of increased propeller noise, the landing gear and overspeed warning horns, and altitude alerts. The King Air descended out of control to 7,000 feet, whereupon the pilots regained consciousness and landed. Major portions of the tail departed the aircraft, and the wing was deformed during the high-speed descent.
Let’s call this a “self-induced” pressurization emergency. Here’s another one:
A pilot picks up his Citation CJ3+ out of maintenance. During climb out, the CABIN ALT light illuminates, indicating that the cabin altitude has exceeded 10,000 feet. He dons his mask, declares an emergency, and initiates an emergency descent. Safely on the ground, he notices that the pressurization controller has been moved to OFF during maintenance, and he has failed to notice it during his pre-flight inspection or climb checklist.
Sometimes, we simply skip the checklist and improvise.
In flight, at FL 400, the M2 pilot notices an amber PRESSURIZATION CNTRL light. The checklist calls for monitoring the situation and descending if the cabin altitude increases above 14,500 feet. Instead, he dons his mask, declares an emergency, and begins a rapid descent. At least he gets credit for putting on his mask.
My point here is that the sequence of events and how you handle them will be different from the rote training repetition in the simulator or airplane. In two of the three scenarios above, the pilots accomplished the most important step.
PUT YOUR MASK ON.
There are scores of examples where pilots took precious seconds to contemplate the situation, only to pass out before they could take action. Donning the mask affords you the time necessary to diagnose the situation.
Can you remove the mask from the receptacle, fiddle with your glasses, and put it in place in time? And what if those prescription glasses are broken or thrown under the rudder pedals during the melee? Do you have another pair nearby?
You might want to have your companion practice the maneuver, too. Patty calls it a really bad hair day.
Fly safe.
