Cloud Dancer
August 1993
West Tennessee Skydiving
Home of Mike Mullin's King Air


Mike Mullin's offers jumps from 23,000 feet. Please see his briefing about those jumps.

Aircraft: King Air B90 N9HW. This aircraft has been retrofitted with 680 hp engines and will climb to 14,000' in 7 minutes and 21,000' in 14 minutes, under standard conditions. Aircraft normally carries 14 jumpers but for high altitude jumps is restricted to 12 jumpers due to the oxygen system installed.

Altitude: Exit altitude will be Flight Level 210, which is 21,000' above sea level with an altimeter barometric setting of 29.92". With the field elevation at Quincy, this will be approximately 20,200' above ground level, depending on the current barometric pressure. Variations in daily 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 should check their altimeters against the other jumpers altimeters and must not set their altimeters from the aircraft altimeter. Free-fall time should be approximately l min, 47 Sec.

Oxygen System: The aircraft is equipped with outlets for 12 jumpers and each jumper is supplied with a "continuous flow" mask. The mask is new when you receive it and it is yours to keep.

Procedure: You will be issued your mask before boarding the aircraft. Upon boarding, locate the oxygen outlet nearest your seat and before sitting down firmly plug your mask into the receptacle. When everyone has plugged into the system, either on the ground or shortly after take-off, you will be asked to test your mask. The pilot will turn on the oxygen and each jumper should place a finger over the supply hole in the mask and it will be readily apparent if pressure is being supplied to the mask. At approximately 10,000', the pilot will tell you to don your masks and will activate the oxygen system. Place the mask firmly over your nose and mouth and tighten the elastic strap. The mask must be held firmly against your face and you must inhale and exhale through the mask. The mask and elastic strap must be placed underneath your helmet if you are wearing a Pro-Tec or similar hard helmet or you will not get a good seal and will not receive the proper concentration of oxygen. If you are wearing a Frapp hat or similar helmet you may wear the mask over the helmet. The pilot will give a two minute to exit warning. At this time get up, get reedy, and continue to breathe the oxygen. When the pilot says "Exit. Exit. Exit" do the following steps in this order: remove the mask from your face by pulling the elastic band on the right slide free from the mask and pulling the mask from underneath your helmet (the free end of the elastic will follow the mask), open the door, jump. The time to perform these tasks is calculated in the exit command. If you wish, you may unplug the mask from the aircraft and take it with you.

The Exit: We recommend a "no show exit" at this altitude as putting out floaters causes exertion that eats oxygen, makes the exit take much longer, and exposes you to an oxygen poor environment for a longer period. Be sure to tell the pilot what type exit you intend to make.

Physiology: Please reed the additional information completely. The time of useful consciousness without supplemental oxygen at 21,000 is approximately 8 minutes. We calculate that the jumpers are exposed to or environment without sufficient oxygen for l min, 40 Sec. This is based on the jumpers removing their masks and exiting the aircraft within l minute and a freefall time of 40 seconds to 15,000', where the time of useful consciousness is considered indefinite. This leaves a buffer of 6 minutes and 20 seconds. Please note that the symptoms of hypoxia and hyperventilation are identical except that you do not turn blue with hyperventilation. Please sit still, breathe normally, and relax.

Questions: If you have any questions please see one of our staff. Our goal is for you to have a safe and enjoyable jump!

PO BOX 381104
Memphis, TN 38183
(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 feet.

Altitude and Performance

Performance can seriously deteriorate within 15 minutes at 15.000' feet. Night vision can be impaired starting as low as 5,000'. Heavy smokers--May experience early symptoms of hypoxia at lower altitudes.

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 accompanying chart).

Preventive measures
1. Refrain from alcohol, and do not smoke prior to flight.
2. Use only medications prescribed by a fight surgeon or aviation medical examiner.
3. Do not fly above 10,000 feet without supplemental oxygen on board.

Supplemental oxygen

FAR 91.211 requires that:
1. Pilots of unpressurized aircraft use supplemental oxygen when flying higher than 12,500 feet msl for 30 minutes or more and at all times above 14,000 feet msl.
2. Every aircraft occupant be provided supplemental oxygen above 15,000 feet msl.

Susceptibility testing

Physiological training--Provided by the FAA. The training includes simulated high-altitude flying in pressurized chambers.

Location--FAA Civil Aeromedical Institute and many military facilities.

Civil Aeromedical Institute

To attend, contact:
FAA Airman Education Programs Branch (AAM-420), Civil Aeromedical Institute, Mike Monroney Aeronautical Center, Post Office Box 25082, Oklahoma City, Oklahoma 73125; telephone 405/680-4837.

Military Training Facility

To attend one of the military training facilities, submit an application form and fee.

Application form--Physiological training application form (AC3150-7) contains locations, fees, scheduling procedures, course content, individual requirements, etc.

How to obtain--From the accident prevention specialist or the office forms manager in the nearest flight standards district office (FSDO) (addresses and telephone numbers for FSDOs can be found in Section 12).

                                    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

Source: "Physiologically Tolerable Decompression Profiles for Supersonic Transport Type Certification," Office of Aviation Medicine Report AM' 70-12, S. R. Mohler, M.D., Washington, D.C.; Federal Aviation Administration, July 1970.

Cloud Dancer