[ derived via archive.org of http://www.skydance.net/sd/highalt.txt ] Your altimeter has gone around two and a half times as you peek out of the door trying to spot and avoid the prop blast. Outside it is 35 degrees below zero inside a toasty 10 below. As you lean outside the water vapor from your face sublimates and frosts your goggles as you try to find your familiar old drop zone 30,000 feet below you. Welcome to the world of high altitude parachuting. During the last 10 years, I have been working with high altitude parachuting and equipment.The search for information and equipment has lead to some interesting places and people. Also, a lot of interested people, especially other jumpers. I hope this article can answer some of the questions jumpers ask and to generally inform other jumpers of the costs and planning needed to complete safe, fun, high altitude jumps. When I first started looking around to find out more about civilian high altitude jumps I found a lot of questions. The first question I asked and continue to ask is : "How much do I really want to make a high altitude jump". It may cost more than 3 or even 4 times as much as a jump from 12,500 feet. It may also take some homework and some time to track down equipment and information, if you want to set up your own system. A good place to start is with the U.S.P.A. bookstore. Part 9.5 in the Skydivers Handbook is a basic introduction to the training and procedures to safely perform jumps above normal sport parachuting altitudes. The next stop would be your local library. Many books written for private pilots have sections on physiology. The medical sections also have information on hypobaric medicine or aerospace medicine. Other sources of information specific to jumping are military manuals used to educate personnel on aerospace medicine and to train military free fall (MFF) parachutists. H.A.L.O. (High Altitude Low Opening) and H.A.H.O. (High Altitude High Opening) are techniques used to insert teams into areas otherwise denied to them. A suggested part of your training and a part I feel is very important, is a Physiological Flight Training Course. These courses, run at military bases around the country and coordinated by the F.A.A., are designed to teach you about the physiology and effects of high altitude. The high altitude chamber run included with the training allows you to experience the effects of high altitude and high levels of oxygen in a controlled environment. You learn how you are individually affected by both of these conditions during this one day course. Applications for Physiological Training are available from the F.A.A. flight service station in your area. Before you can send in the application you must have received at least a F.A.A. Class 3 medical exam. This is the same exam given to student pilots. A local pilot should be able to refer you to a doctor that offers these exams. Some doctors also mention their ability to do F.A.A. physicals in their yellow page ads. Due to current cut backs of military budgets the number of hypobaric chambers has recently been greatly reduced. This has lead to quite a back log of applicants waiting for this training. Currently in some areas this wait can be months. If you can travel to a chamber outside your area it may help speed the process. Even if you never jump at high altitude, the chamber run and training may help you understand why you once saw the jumper sitting next to the window talking to someone outside the aircraft on that 15,000 foot jump you made out of a DC-3. Time again to ask yourself, " How much do I really want to make a high altitude jump". The next step is finding equipment and aircraft to get you safely up to and down from the altitude you wish to jump from. First question, "What is high altitude?". Different groups define "High Altitude" differently. For this discussion Iwill use the definitions found in U.S.P.A. Part 9.5 High Altitude Doctrine. High Altitude: 20,000 to 40,000 feet above sea level. Most of my jumps are in the 24,000 to 30,000 feet above sea level range with others being from higher altitudes. It should be noted, that this is feet above sea level, not above ground level. By now all of the information you have learned tells you supplemental oxygen is needed to jump at these altitudes. The physiological effects of these higher altitudes have started below 20,000 feet above sea level but things get rapidly more dangerous above the 20,000 foot level. Even at altitudes as low as 10,000 to 15,000 feet above sea level it becomes a question of how much you are affected by the changes in the atmosphere, not if you are affected. Most people can function at normal jump altitudes, 7,500 to 15,000 feet above sea level for short periods with only minimal detrimental effects. As you ascend, the percentage of oxygen in the air does not change very much but, the ambient pressure decreases and the oxygen available to the tissues of the body decreases. This condition referred to as hypoxia (oxygen deficiency) can manifest itself in many forms. Briefly, the effects may be headaches, tunnel and reduced night vision, slowed reactions, euphoria, tingling, faintness, an unusual feeling of confidence, emotional disturbances, cyanosis; bluish coloring of the skin particularly noticeable on the lips or under the fingernails, or a whole series of other symptoms eventually leading to death at higher altitudes. In general, the effects of hypoxia will start to greatly effect most people above 10,000 feet above sea level. Of the four generally recognized for insufficient oxygen supply in normal jump situations. The drop in the partial pressure of oxygen at altitude is the cause of this type of hypoxia. Even though the percentage of oxygen in the air has remained basically constant, you can not utilize the oxygen due to the drop in pressure. The other types of hypoxia are: Hypemic hypoxia, a reduction in the circulating hemoglobin due to anemia or excessive smoking. Stagnent hypoxia, oxygen deficiency due to poor circulation and Histotoxic hypoxia, caused by the inability of the blood to use oxygen usually caused by alcohol or drugs. Even drugs such as those found in over the counter cold medicines can affect you at altitude. Hyperventilation is another stress put on the body at high altitudes. When you hyperventilate, your respiratory rate and depth abnormally increase. This may be in response to hypoxic conditions but it may also be caused by stress or other factors. The early symptoms are almost identical. Either way you are using more effort and that can influence how you physiologically react to conditions at altitude. Jumpers who smoke may be physiologically several thousand feet above non-smokers on the same load. Some people get a claustrophobic feeling when wearing the mask for anything over a few minutes. I have watched someone on 100% oxygen start to hyperventilate due to the stress of just sitting in a small aircraft with the mask locked onto their face. You may be wearing the mask for up to two hours on higher altitude jumps. At 18,000 ft. above sea level you are at 1\2 sea level pressure at 34,000 ft above sea level you are 1\4 sea level pressure. Just like a SCUBA diver returning to a lower pressure at the surface, as you go to higher altitudes, you can experience decompression sickness (DCS) Decompression sickness is caused by gases, mostly nitrogen, in solution in your tissues turning to gas. DCS may manifest itself as the "Bends" gas bubbles forming in joints or tissues, or a group of other symptoms such as the "Chokes" gas bubble blockage of blood flow in the lungs or the Creeps", gas bubbles under you skin and a variety of central nervous system disorders. The chokes has been described as causing burning pain at or near the base of the sternum shortness of breath with an ineffective cough. The creeps is said to cause an itching, tingling sensation under your skin. Descent to a higher pressure while breathing 100 % oxygen is the only way to immediately treat these problems. If any of these symptoms occur, within 72 hours of a high altitude jump then a doctor with training in hypobaric medicine should be consulted immediately. A way to greatly reduce the chance of encountering any problems with decompression sickness is to prebreath 100 % oxygen for 30 minutes if you are going to jump at 20,001 to 25,000 feet above sea level, one hour if you are going to 25,001 to 30,000 feet above sea level and two hours if you are going to 30,001 to 43,500 feet above sea level. The prebreath needs to start on the ground in most situations. The prebreathing flushes most of the nitrogen from your tissues. You continue to breath 100 % Aviators Breathing Oxygen as you climb to jump altitude. A single breath of atmospheric air after starting the prebreath can negate a large portion of the protection the prebreath offers. Aviators Breathing Oxygen should be used in jump operations. Other types of oxygen, such as medical oxygen, have a great deal of moisture in them. This moisture can freeze inside the regulator, hose or mask and block the flow of oxygen. Also, wait 24 hours after diving underwater before jumping. These procedures may seem very conservative but the consequences of any of the potential problems seem to offset the additional time and expense. While it is uncommon for "average" people to encounter evolved gas disorders below 30,000 feet above sea level there are several reported incidences of problems below 25,000 feet above sea level. It is always a question of who is "average". In most tests the subjects are young and physically fit. How do you fit into that sort of " average". Trapped gas expansion is another problem. The gas trapped in your gastrointestinal tract, sinuses, ears, teeth or anywhere else will expand while you ascend. Fortunately while on 100% Oxygen you will not be able to smell the cabin interior. This can cause headaches, earaches, toothaches or stomach pains. Do not eat gas causing foods for 24 hrs. before the jump, this includes carbonated drinks. Alcohol and other drugs can also cause major problems at altitude. Your research and Physiological Flight Training Course will have taught you the other physiological problems you might encounter. As you climb higher, the time you will remain conscious and be able to help yourself or anyone else if you have a problem with your oxygen system gets very short. This time, known as time of useful consciousness, (TUC) has been determined by experimentation in high altitude chambers. See table for details. By looking at the times listed in the table, you can see that at say 22,000 feet above sea level you have about 10 minutes before you are non-functional. This would allow you to fly up to 22,000 feet with an onboard system and then just before exit remove the mask and quickly jump. Theoretically, before you became hypoxic, you would have reached an altitude where oxygen would no longer be needed. Unfortunately, the way this sometimes works in the real world is not as planned. The table for TUC is for someone at rest. Any extra effort will shorten the TUC Also, the TUC does not tell you when you become hypoxic, only when you may reach a point where your performance will deteriorate so badly that you will not be mentally and physically able to do much. After you remove the mask at altitude, you will normally start to hyperventilate to compensate for the changes from altitude. This will take some extra work. Combine this with moving in the aircraft the general excitement of the jump low temperatures and perhaps a longer then expected jump run and you may have some hypoxic jumpers even before you leave the aircraft. Jumps of this type also sometimes lead to equipment loss and fatalities. Several times I have seen someone almost forget to remove an oxygen mask before exit, OOPS! Also, a few years ago, one jumper died from what are believed to be hypoxia related problems on a jump from the mid 20s. The person who died exited the aircraft and was never seen in freefall by the other person on the load. His body was found with no indication that he had done anything to save his life. The use of "Buddy Teams" to watch each other for symptoms of hypoxia or any other problems will help reduce the chance of problems. This buddy team idea can be used form gearing up to landing. each team member does a complete jumpmaster check, including the oxygen mask and bailout system, if used, after the gear is on. They also observe their "Buddy" for any symptoms of hypoxia or decompression sickness during and after the jump. Like divers under water, parachutists seem to ignore the little warning signs that their body tries to give them. In this case, it may mean more then a sore back or knee. Admitting there may be a problem is a lot safer then waiting to see if there is a problem. Some one should be assigned to check the pilots oxygen system and to watch the pilot for any symptoms of hypoxia and decompression sickness during the flight and after. Yes, I have heard that has happened also. When the pilot passes out while flying the aircraft it can be a real interesting situation in any aircraft. I use and suggest using a trained oxygen monitor to watch the pilot, jumpers and check equipment. We also do a complete independent jumpmaster check before boarding the aircraft. Back to the aircraft. The turbine and turbocharged aircraft used at many drop zones give you a chance to reach altitudes over 20,000 feet above sea level. A talk with the pilot and the owner/operator of the drop zone is your first step. The location of some drop zones precludes high altitude jumps. Commercial or military traffic over or near the drop zone can limit use of the airspace or keep you from jumping there at all. Remember, the altitudes you are flying in are controlled airspace and jump activities are not common from these altitudes. Normally at least one commercial airline pilot monitoring the radio communication between the jump pilot and the controller will make some comment about the sanity of the jumpers involved. On the last 30,000 MSL jump made in October at Skydance in Davis CA one pilot said that they were a sport jumper and that they were jealous. A flight plan needs to be filed before the jump. Also coordination with the F.A.A. can ease the conflict of airspace problems. Most jump pilots will be aware of the airspace limitations for the area they fly in. They will also know the performance limits of the particular aircraft they fly. The owner or the owners insurance company may also place limits on the aircraft. Remember, the jump pilot is a very important part of the team to get you to altitude. This is especially important because the aircraft you use will most likely be near its service ceiling during your jump. Also, remember to include your pilot(s) on your chamber ride if they are not current at the time of the jump. Oxygen systems are of three basic types. Constant flow, good to 30,000 feet above sea level, Diluter Demand, usable up to 33,000 feet above sea level if a separate bailout system is used and Diluter Demand/Pressure Breathing, good up to 43,000 feet if positive pressure breathing is used in conjunction with a separate bailout oxygen source. Many turbocharged aircraft have a constant flow system designed for the altitudes where the aircraft will normally be flown, the high teens to low 20's, and use masks not designed for free fall. Pilots and some jumpers in the audience will ask "What about nasal canula?". A nasal canula is a delivery system generally used with constant flow systems. The oxygen flows thru a small tube that ends in two tubes which are placed in each nostril. The canula is light weight and keeps the pilot or jumper from having to wear a mask. The problem is a question of how much oxygen is really getting to the lungs. While useable in the lower altitudes of this range, I do not recommend their use. In general these systems are not suitable for the higher range of altitudes we are talking about and are not suitable for free fall. Some constant flow systems commercially available are useable to 30,000 feet MSL but these systems use masks and hoses not designed for free fall or for a true 100 % breathing. Many of the masks use a bag to rebreath a portion of the gases expelled from the last breath or mix a portion of the ambient air. Diluter demand systems are less common in most small aircraft. Also, at the higher altitudes, an oxygen source should be used in free fall or under canopy. Some aircraft will have Diluter Demand systems for the pilots and a free flow system for the passengers. Diluter Demand/Pressure Breathing systems are very rare in the jump aircraft used at most drop zones. With both the Diluter Demand and Diluter Demand/ Pressure breathing systems the masks used inside aircraft, unless military, are many times not suitable for free fall. Because of the restricted visibility due to the mask a wrist mounted altimeter and a very good familiarity with your rig are essential. The best way to practice this is to put on your rig then the helmet, mask and goggles and then locate the handles. A hanging harness is even better. Seeing anything on your chest is very difficult. Free fall speeds of 150 MPH while in a normal stable body position can be experienced. Wind chill factors of -100 degrees below zero are not uncommon. It is of little comfort when the wind chill chart says wind speeds over 40 MPH will not affect the wind chill factor very much. One thing to be careful of is wearing to much clothing. Remember you will be sitting in a nice aluminum aircraft for anywhere from 30 minutes to 120 minutes when you are prebreathing. For this reason it is suggested that the prebreath starts as early as possible in the morning so that overheating is not a problem. Also even with sub zero temperatures massive layers of clothing may not be needed. Another suggestion is to prehydrate the night before the jump. This means drink lots and lots of plain, not carbonated, water so that your tissues are fully hydrated. This will help mitigate the dehydration you will experience just due to breathing a very very dry gas, the Aviators Breathing Oxygen. If you drink a lot just before the jump it can lead to some unpleasant experiences during the prebreath and jump. Some people have been a bit overdressed on jumps and have sweated a lot also. One other thing is to try everything on before the jump to ensure that it is comfortable and does not cover any handles etc. Due to the higher speeds in freefall your goggles need to be snug but not too tight. Twice now people have had problems with goggle straps made of surgical tubing either pressing on the pressure point on the back of their head or wrapping their hair and causing problems. Another suggestion is to bring something to read or do during the prebreath. Magazines, playing cards, paper and pencil and even the game rock paper scissors have all come in handy. During the prebreath and climbing to altitude try to minimize the amount of time your goggles are down. The less moisture the less fogging problems. You have found an aircraft, set up onboard oxygen equipment, found enough masks, bailout sets, helmets, hardware and warm clothing. Now it is time to for a practice jump and dry runs in the aircraft on the ground. With the masks on it is almost impossible to talk to each other. Hand signals and written notes are the cheapest way to communicate. A pencil and paper or small chalk board and chalk are good pens can freeze up.The doctrine suggests that A.A.D.s be worn on all high altitude jumps. Besides the normal jump hazards high altitude adds the other potential physiological problems mentioned before. A preferred position for the A.A.D. is on the main container. This is because if a premature opening occurs and you are still conscience you can easily cut away the main and free fall to a lower altitude to open your reserve. Since most containers have a hand deploy or pullout system mounting the A.A.D. to activate the reserve is the only option. The use of A.A.D.s is a very individual decision. Still... Before using any altitude sensing equipment such as altimeters, audible altitude warning devices or A.A.D.s at high altitude you should contact the manufacturer and ask about the limits they place on their equipment. A quick run up to your jump altitude in a testing chamber would also test your individual equipment. I have found that everyone's altimeter will be reading a different altitude as they ascend above normal jump altitudes. Also they all seem to peg at different altitudes. The aircraft should be electrically grounded when oxygen is in use. The last major consideration is drift during freefall and under canopy. The winds aloft at the higher altitudes are many times stronger and more varied than at normal jump altitudes. The best way to compute the drift is to use the military computation and technique. To do this properly, you will need a chart of the area around the drop zone, a straight edge, protractor, clear overlay, marking pencils to write on the overlay and a calculator to speed things up. A call to the local flight service station will give you the winds aloft as reported to the F.A.A.. The actual winds are many times different than those reported. So, as you climb to jump altitude ask the pilot to compute the winds aloft at 3,000 meter, 9,840 foot, intervals during the climb. For free fall use the formula D=KAV. (D) drift, equals (K) a constant (3), multiplied by the altitude (A) in thousands of feet and the velocity of the wind (V) in knots. A parachutist will drift 3 meters, 9.75 feet, for every 100 feet of fall for each knot of wind. If you are computing drift while under a open square canopy, use K=4. As you compute the distances and directions of drift lay them out on the overlay over your chart. This gives you a visual idea of where you need to get out to open over the drop zone. You may also mathematically figure how each component of drift cancels each other and make a guess where to get out. A good spot figuring a 2 to 3 times greater forward throw will work many times. Remember, the aircraft will be flying 30 to 60 miles per hour faster then normal when you exit. Also, do not expect much if any cut. The aircraft will need to stay at a higher airspeed. After you get out try to resist the urge to track to the target while still at high altitude. Also, remember to wear comfortable walking shoes and to carry change for a phone call. That is it, you are ready to make the jump(s). Only one more question, "How much do I really want to make a high altitude jump?". With persistence, and prior planning, it can be done in a safe manner. Personally, the whole process has been worth it to me. The color of the sky and the nature of the light at 30,000 feet and above are a lot different than at 12,500 feet. Even with exit speeds of over 100 knots the exits are mushy like subterminal air and flying in freefall is just enough different that it has a very unique feel to it. Even skygods can have problems and few formations, free flown, get together quickly out the door. Last of all the view is incredible. If you interest is more in canopy relative work then you can also expect your canopy to fly differently and not as efficiently at high altitude. We have looked at a first jump from 24,000 to 30,000 feet like a first night jump, separate exits and no formations. As an example of spotting problems and responses to the jump last October we trained and put out one load of jumpers from 24,000 feet and two loads of jumpers from 30,000 feet. Everyone said it they had a great time, even if one spot was off due to 20 knot winds that came up between 2,000 and 12,000 feet after take off. From 18,000 to 30,000 the winds were blowing 50 knots from the NE. From 12,000 to 2,000 feet they were blowing 20 knots from the WNW. Remember, check for changes before exit. One final note, I will be the first to admit that I tend to lean toward the use of oxygen equipment and techniques that the military has used. The equipment is rugged and the methods tested. For me, at the altitudes I normally help people jump from 24,000 to 30,000 feet MSL, they have worked well. So far, I have helped over 100 jumpers make jumps at these altitudes. Other systems using constant flow do work well but as you go above 20,000 feet MSL they loose some of the safety factor I personally look for. I currently use MBU 5/p and MBU 12/p masks with CRU 60/p connectors hooked to H-2 oxygen cylinders for the jumpers we train. I personally use a AIROX-8 regulator hooked to a twin bottle bailout system. This system allows me to disconnect from the onboard system and move around the aircraft if needed to deal with emergencies. I also currently use a 8 person console that I designed using A-14A pressure demand regulators set on 100 % Oxygen. We have also used constant flow masks, not canula, up to 24,000 feet MSL with success. With both my console and the constant flow system 100% oxygen breathing starts on the ground and continues until just before the jump on jumps at 24,000 feet MSL or below. On jumps above 24,000 feet. MSL we have only used the pressure demand masks. In both cases everyone including the pilot is on 100% oxygen constantly from the start of the prebreath to, in the case of the jumpers, after they have reached an altitude where their bailout oxygen has started to mix with ambient air. The pilot will many times stay on the onboard system until landing because it is easier to continue to use the mask mike then fiddle with changing plugs etc. when flying. Normally the jumpers release one side of their masks after opening. This allows easier breathing. At lower altitudes you will be pulling some ambient air through an anti-suffocation valve built into the manifold connector. If the mask is released from both sides of the helmet it can be damaged more easily on landing. We have also required that everyone jumping with us has been through Physiological training and has a third class medical. Goggles/Helmet: Many types of goggles can be used. The important part is that they allow the best visibility possible and cover the exposed skin around your eyes. One person I know used his regular Kroop goggles on a jump from 28,000 feet. The temp was 40 degrees below zero. Right outside the door the goggles frosted, froze and shattered when he pulled them away from his face to clear them. Until he reached a lower altitude he had to protect his eyes by initially closing them and then peaking thru the fingers of the hand he put over his exposed skin to keep it from getting frosted. His face looked like he had a major sun burn when he got to the ground. Most of the time these goggles have worked ok except for the fogging problems. More skin coverage above the mask would be better. Keep your goggles up and off your face until just before the jump, especially if you are sweating, to minimize the frosting problem. I have used open face fiberglass motorcycle and flight helmets with receivers attached to hold the mask to your face. Communications can be easily added to these helmets. Plastic helmets may become brittle and shatter in the cold at altitude and other styles do not offer much protection both from the cold and the potential for higher speed impacts at altitude. It is also difficult to mount mask receivers to some styles of helmets. Altimeters: According to the various manufacturers, their equipment can be used up to the following altitudes. The Altimaster series of altimeters can be use up to 30,000 feet above sea level. From my experience, the needle will go around two and one half and a little more then peg around 30,000 to 33,000 feet above sea level. The altimeter can be taken above the point where it stops without damaging it but will not indicate the altitude, I have taken mine above 35,000 ft. As you descend, the indicator will start to move as you pass the altitude where the indicator stopped. The Paralert uses the same sensing device and can go to the same altitudes. The Dytter is useable to 60,000 feet above sea level. The altitude warning setting can be set as high as 10,000 feet. North Star Altimeters can make two revolution allowing use up to 20,000 and 40,000 feet respectively depending on the unit being used. Cypress A.A.D.s do not have an altitude limit. For information on other altimeters, or equipment contact the manufacturer. Remember, use your built in binocular altimeter to cross check. I normally use a wrist mount and audible altimeter on these jumps.