Cloud Dancer

World Freefall Convention at Quincy, IL
August 1999
West Tennessee Skydiving
Home of Mike Mullin's Super King Air


Aircraft: King Air B90 N9HW, retrofitted with 750 HP PT6A engines, high performance cowlings, 4 bladed props, will climb to 14,000' in 7 minutes and 23,000' in 14 minutes. Aircraft normally carries 14 jumpers but for high altitude jumps is restricted to 12 jumpers due to the oxygen system installed.

Altitude: Exit altitude is Flight Level 230, which is 23,000' above sea level with an altimeter barometric setting of 29.92". With the field elevation at Quincy of 769', this will be approximately 22,231' above ground level, depending on the current barometric pressure. Normal variations in barometric pressure can change the exit altitude plus or minus 300' above ground level. Jumpers should set their altimeters to zero at takeoff and should not adjust their altimeters in flight. At high altitudes it is not uncommon to see differences as large as plus or minus 500' between typical skydiving altimeters. Jumpers must not set their altimeters from the aircraft altimeter. Skydiving altimeters will usually stop recording at some point on the climb--needles will stop moving or digital displays will go blank. They will usually start working on the way back down. Free-fall time should be approximately 2 min, 4 Sec.

Oxygen System: The aircraft is equipped with outlets for 12 jumpers and each jumper is supplied with a "demand" type aircrew mask that supplies 100% oxygen on each inhalation. These masks have a FAA TSO and are certified to 40,000'. The masks are very expensive so please take care that they are not damaged.

Procedure: Before boarding the aircraft, you will be issued a "Sani-Com" packet which is used to clean your mask prior to use. These cleaning packets are the airline industry standard for cleaning crewmember masks and contain a non-toxic germicide. Upon boarding, locate your seat, sit down, fasten your seat belt, and remove your mask from its holder by squeezing its retaining buckle. Clean the mask and place the Sani-Com wrapper in your pocket or jumpsuit. The oxygen system is not on at this time and will not deliver oxygen. At 10,000', the oxygen system will be activated. As the masks are demand type, you must place the mask firmly over your mouth and nose and inhale to start the oxygen flow. It will be very obvious that oxygen is flowing each time you inhale. You should both inhale and exhale through the mask, that is, do not remove the mask from your face to exhale. Important: If, while inhaling, you remove the mask from your face, the oxygen will continue to free-flow through the mask until you again seal the mask to your face and exhale. This is normal and the only problem it causes is to waste oxygen. Important: It is not necessary to inhale the oxygen more than once every 5 seconds and greater use may lead to hyperventilation. Inhale and exhale through the mask and count slowly for at least 5 seconds before inhaling again. Do not hold your breath--holding your breath accomplishes nothing.

Occasionally, your mask may become disconnected from its receptacle. Reconnect the mask by pushing the fitting on the end of the hose back into the receptacle while turning it 1/4 turn clockwise.

About 2 minutes prior to exit, the pilot will give a two minute warning. At this time get up, get reedy, and continue to breathe the oxygen. The next command will be "hang your masks up" followed immediately by "Exit. Exit. Exit." At this time, snap your mask back to its holder, open the door, and exit the aircraft. The time to perform these tasks are factored into the exit call so do not rush, but do these tasks in a timely manner. Please be certain your mask is securely snapped to its holder anduse caution that your arms or head are not snared in the loops formed by the dangling oxygen hoses.

The Exit: You may use any exit you desire but a "no show exit" is recommended at this altitude due to the time and exertion that is expended in an oxygen poor environment putting out floaters. Be sure to tell the pilot what type exit you intend.

Physiology: Please reed the additional information completely. The time of useful consciousness without supplemental oxygen at 23,000 is approximately 4 minutes. The jumpers are exposed to an environment without sufficient oxygen for l min, 54 Sec. This is based on the jumpers removing their masks and exiting the aircraft within l minute plus a freefall time of 54 seconds to 15,000', where the time of useful consciousness is considered indefinite. This leaves a buffer of over 2 minutes. Note that the symptoms of hypoxia and hyperventilation are identical except that you do not turn blue with hyperventilation. Sit still, breathe normally, and relax. If you are turning red, you are most likely hyperventilating--slow your breathing and relax.

PO BOX 381104
Memphis, TN 38183-1104
(901) 465-DIVE


Cause: Deficiency in the amount of oxygen that reaches the body's tissues (e.g. exposure to altitude with progressively insufficient oxygen at higher cabin pressure altitudes).

Effect: The central nervous system, brain, and other organs cannot function properly.

Contributing Factors: Smoking, alcohol, drugs (including antihistaitanes, tranquilizers, sedatives, and analgesics), anemia, carbon monoxide, fatigue, and anxiety.

Manifestation: It is impossible to predict when or where hypoxia will occur during a given flight or how it will manifest itself, particularly if it occurs gradually.

1. Increased sense of well-being (referred to as euphoria) or belligerence.
2. Rapid breathing.
3. Slow reactions.
4. Impaired thinking ability.
5. Unusual fatigue.
6. Dull headache.
7. Warm or tingling sensations.
8. Sweating.
9. Loss of or reduced vision.
10. Blue discoloration of the Fingernails and lips.

Note: The symptoms are slow but progressive, insidious in onset, and most marked at altitudes above 10,000'.

Altitude and blood-oxygen saturation:

Sea level--about 95 to 98 percent.

10,000 feet--About 90 percent; you could begin to experience some of the symptoms of blood-oxygen starvation.

14,000 feet--About 84 percent; thought, memory. and judgment processes are substantially impaired. Peripheral vision may be affected, and hands could begin to shake.

16,000 feet--About 77 percent; you may not be capable of controlling the aircraft and could even lose consciousness.

18,000 feet--loss of consciousness could occur in 15 to 30 minutes.

Above 18,000 feet--Effects of hypoxia are described in terms of time of useful consciousness, which ranges from 10 minutes at 20,000 feet to 15 seconds at 40,000 feet (see the following chart).

                                    Tlme of useful
        Altitude (ft)                without oxygen

           40,000                    15 seconds
           35.000                    20 seconds
           30,000                    30 seconds
           28,000                     1 minute
           26,000                     2 minutes
           24,000                     3 minutes
           22,000                     6 minutes
           20,000                    10 minutes
           15.000                    Indefinite

PO BOX 381104
Memphis, TN 38183-1104
(901) 465-DIVE

Cloud Dancer