May 13, 2008

Soar Minden
Glider Flying Information

Glider Wave Flying

Soar Minden is world famous for its wave - and rightly so. June is historically the month with the second must wave days, and this month has continued the pattern with ten days so far.  The wave will probably taper off in July, but cross country flying will continue in thermals and the wave will pick up again in three months or so.  

We'd like to post some thoughts on wave flight for pilots who are thinking of coming to take advantage of this natural phenomenon.

On Wave Prediction

We look at weather development over the North Pacific to get early indication of wave activity off the Sierra's east escarpment. You can find 300 millibar (approximately 30,000') imagery at San Francisco State University and also animated to help track approaching weather that might generate wave at Minden. (Minden is located where the California/Nevada border makes a 45 degree bend.) These will give you an idea of wind direction and speed, and we look for westerly winds between 210 degrees and 310 degrees) of 25 knots or more to make wave. We also look at wind gradient above the ridge - an increase in speed of at least one knot per thousand feet is ideal.

From experience we can say that we will have wave every month of the year. The period with the most frequent and strongest wave, though, will be from the beginning of November through the first week of June. Much of this period also brings the most moisture, so for several months - especially January and February -- we will have days when we cannot fly because of low ceilings or snow on the ground.

Inclement weather usually passes quickly in northern Nevada. And wave conditions frequently follow storms, so don't be discouraged if you have several days of bad weather during your stay: the chance of wave increases after the storm's passage.

In order to predict wave more than five days or a week in advance we need to look at climate rather than weather. This is where experience comes into play, and our experience is that we will have wave two or three days in anytwo week period during the best season. If you want to be sure to fly in wave you will probably want to schedule ten days or two weeks here. You might fly in wave the first day, or you might fly in wave the last day, but you will almost certainly fly in wave. And you will almost certainly earn a diamond altitude badge.

About Turbulence on Tow

Wave is a function of high velocity wind flowing over the face of the Sierra Nevada Mountains to our west. If you have seen water forming a stationary bump on the downstream side of rocks in a stream you have seen an example of standing wave. Remember that the stationary bump in a stream is often accompanied by white water and turbulence.

In the lower portions of the flight, before you enter laminar flow, you will be flying in air that is often churning and rolling with quite a bit of force. Your tow will take you through rotor and shear to reach smooth lift. You need to be prepared during the tow for rapid changes in your flight attitude: very strong lift followed by very strong sink and rolling motion that you have probably not experienced in other flying. You will be working hard to stay in position on tow. You must be buckled securely into the glider, with the hip and shoulder straps pressing you into your seat. You must also secure loose articles: water bottles and cameras will go through a Plexiglas canopy very easily, and so will your head if your shoulder straps do not restrain you. We strongly recommend you leave all loose articles behind.

Your tow pilot has lots of experience finding wave and he will try to take you to the best spot on that particular day. Ask him in advance if you want him to make a recommendation on when to release. If yours is not the first flight of the day he will know where previous tows have resulted in good wave entry and he'll be glad to call on the radio and recommend release.

The very smooth portion of the lift can start a few thousand feet above the ground, but it is not uncommon to tow five or six thousand feet above our field elevation (4,718') to be sure to enter the wave. You will know when you enter laminar flow - the smoothness of the lift must be experienced to be believed, and your vario will be indicating 500' to 1,800' per minute climb (or more), even though you won't have the sensation of movement.

Stay Out of Cloud!

Once you are established in smooth lift you need to remember you are climbing in air that is moving from west to east at high speed. If you do not match your air speed with the wind velocity you will be blown downwind - very likely toward the lenticular cloud. All the cautions (and FAR requirements) you have heard about remaining clear of cloud are doubly important now; you must keep an eye behind you on the cloud, and below you to some ground reference, to be sure you are not being moved back into the cloud.

You also need to watch the cap cloud on the crest of the mountains to be sure it is not "growing" out into the gap. If the day is particularly wet the gap can close quickly and you will have to fly north or south to the end of the lenticular cloud, or above and to the east (behind it), to descend in clear air.

People who have been blown into cloud have used the benign spiral mode to descend through it. If this is your only option and you have been trained in the maneuver you still need experience in the specific glider you are flying so you are comfortable with it. You do not want to be trying a benign spiral for the first time when you are in the clouds. If you think you might need to use this, practice it before you need it; better yet is always to remain out of cloud.

Decreased VNE at Altitude

Wave formation depends in part on wind speed increasing with altitude. This means as you climb you will have to increase your IAS just to remain stationary over the ground. You need to remember the glider's designer established VNE to protect you from flutter of the control surfaces. Since flutter is based on True Airspeed, not Indicated Airspeed, VNE will decrease as you climb. A placarded table inside the glider specifies the VNE at successively higher altitudes. Your safety depends on observing these speeds.

Using Oxygen

Federal regulations require pilots to use oxygen when above 12,500' MSL for more than 30 minutes. Many pilots coming to Soar Minden for the first time will arrive from a lower elevation, so just walking around at our 4,700' field elevation will be tiring. No matter where you come from your flying will demand a clear head. Supplemental oxygen is helpful in keeping a clear head, and the symptoms of oxygen deprivation are so subtle that you cannot trust your senses to tell you when to start using oxygen. High altitude familiarization courses are available in hyperbaric chambers at about a dozen USAF bases for a small fee. Check out FAA website for additional information.

Our recommendation is, if you anticipate strong rotor, start your tow on oxygen so you will not be trying to don your mask or cannula when the glider is pitching and rolling. If you have experience putting on your mask, and are comfortable doing so while flying, you can probably wait until you reach 10,000' MSL before donning the mask and going on oxygen.

A nasal cannula will be sufficient (and less cumbersome) if you will be flying below 18,000'. If you plan to enter the wave window you will be using an A14 regulator and mask with built-in microphone. You should have a briefing before using this so you are comfortable with the settings on the A14. An incorrect setting on the diluter lever, for example, will increase oxygen consumption dramatically and could cost you a diamond.

Dressing for Cold and Sun

Flight in wave will be cold. Portions of your body exposed to the sun through the canopy might feel comfortable - you are in a "greenhouse," after all - but your feet will probably be very cold. Soar Minden has some "loaner" coveralls, but you should pack thermal underwear and gloves for your trip here.

In addition to giving you cold toes, the low temperature has two other very obvious symptoms: it will frost your exhaled breath on the inside of the canopy and it will cause your kidneys to excrete liquid at an accelerated rate.

Rubbing the canopy frost with your gloves will damage the canopy: please refrain from doing this. A little fresh air through the side or front vent will help delay the buildup of frost, but it will quickly lower the inside temperature. It is still the best cure, though. There is little you can do about the second symptom. Plan for it in advance by making a bathroom stop before you take off. And remember your body is dehydrating more rapidly because of the cold.

Another consideration of high altitude flight under a Plexiglas canopy is UV exposure. You can burn quickly and badly at 25,000'. There is sun block available at the front desk. Help yourself to this for exposed portions of skin, but remember sun block and lip balm as well as any petroleum based product will spontaneously combust when exposed to oxygen: don't use them inside your mask or around your cannula.

The Wave Window

Soar Minden is ideally located to take advantage of three wave windows that have been established by Letter of Agreement with the FAA at Oakland Center. These wave windows are blocks of Class A airspace that we can usually get permission to enter so we can climb to diamond altitude.

We open the wave window from our office by telephone with Oakland Center. To do this from the air, call down to Soar Minden on 122.8 and ask them to "go to three" (123.3). Once on 123.3, tell the front desk your location over the ground, your altitude, and your rate of climb. Based on that information the front desk will ask Oakland Center to open the appropriate window to a specific altitude.

Sometimes they can do so immediately; sometimes they will ask us to delay until they can clear commercial traffic out of the airspace. A delay means you MUST remain below 18,000' until that delay has passed. For this reason it is a good idea to call the front desk as soon as you are clearly established in smooth lift.

All three of Minden's wave windows have specific boundaries that you must observe. Oakland Center will know when a pilot strays out of the boundaries, and to do so jeopardizes our use of this airspace. Please be familiar with the landmarks that set the boundaries and stay inside those landmarks.

X-C in Wave

Since mountain wave is generated by the Sierra escarpment it stands to reason that you can fly long distances parallel to that mountain range. Record flights have been made out of Minden by doing just that, and you can see by looking at a map that a wave flight from Susanville to Mojave (and return!) could be planned when conditions are just right.

Unless you have extensive X-C wave experience you will probably not make a world record flight on your first try. You'll have fun, though, and can certainly try for a gold or diamond distance flight, so put that on your wish list. Soar Minden has instructors with extensive cross country wave experience who will be glad to work with you to practice a badge flight in a two-place glider or to prepare a solo badge flight.

A cross country flight in wave adds extra safety and comfort considerations to the planning process. Review your X-C texts, aero-medical factors checklist, parachute use (especially in high altitude/high wind situations) and navigation. Carry extra water (well secured in the cockpit) and energy food. And don't forget to declare your flight in advance if you're trying for a goal!

Flight Loggers, Barographs and Badges

Soar Minden has barographs and flight loggers you can rent and personnel who can act as your Official Observer for badge flights. Please ask for a briefing on their use, especially regarding notch requirements. It is not always easy to put a notch in a barograph trace when the vario is pegged up!

Speaking of notching, the secret is to descend at least 200' and wait two full minutes. Don't dive the glider; if you can't descend by lowering the nose slightly, you'll have to use the spoilers to hold yourself down. The good news is if you have to use the spoilers to hold yourself down you're probably in reliable lift.

Soar Minden staff can also be an Observer for a flight you make using your own logging equipment, but we do not always have the correct cables and software to move the log to our computer. Since our Observer must retain custody of the file and transmit it directly to the SSA, plan to provide a means of transferring it securely to our computer (cable and software) if you want to use your equipment. Check with us in advance if you have any doubts.

You will need to be an SSA member to have your badge claim processed by the SSA. If you are not an SSA member, the SSA will, upon payment of a small fee, forward a badge claim to another nation's soaring association for awarding of a badge by that association. If you are trying for an FAI award you will need to be an FAI member. SSA membership no longer includes FAI membership; you will need to arrange membership directly with FAI, through NAA if you are a U.S. citizen.

Landing After a Wave Flight

You've just descended (not always easy to do in wave conditions) from 30,000' or above, you're fatigued, cold and slightly dehydrated, but you're still in smooth air and thinking the hardest part of the flight is over. Think again.

Wind speed will very likely have increased while you've been up. Wind direction might have changed too, and the air below the laminar flow will be turbulent, possibly more so than when you towed up to begin your flight.

You will need to re-secure loose items like cameras that you used while in the wave. You will want to listen to AWOS (119.325) to check wind speed and direction while you still have sufficient altitude to change your pattern to a different runway. You should plan for considerable wind shear as you descend. For safety, remember to increase airspeed in the landing pattern. And you will need to think about making the glider secure on the ground, including the canopy. Call the office before you land to alert us of your arrival so we can have ground crew standing by to help you.

When is the Best Time for Wave

For us, a day counts as a wave day if a pilot flying out of Soar Minden reports laminar lift, and especially if we open the wave window with Oakland Center. The result is, we only report what we experience.  

Our own anecdotal evidence points to March as the month with the most days of wave -- 19 days when our chart was made up (about 4 years average). January and June are the second highest averages on our chart -- 16 and 18 days respectively. In fact, looking at the chart, one would conclude that the wave year is fairly constant, with about 15 days of wave on average between November and June. The number of wave days drops into the single digits in July and stays low through October (7, 5, 4 and 5 days respectively for July - October).

But "best" might also be interpreted as referring to the strongest, or highest, wave. We do not collect anecdotal evidence on that so we cannot tell you what months offer the strongest or highest wave. Gut-level recollection of local pilots indicates that December and January offer the greatest altitude but flights above 30,000' can be made most months of the year.

Finally as to when the best wave for the entire Sierra Nevada forms: This calls for more information than we keep on hand, but it is a good question because of the number of pilots who want to make long distance wave flights out of Minden. For them, knowing what the wave is doing in Minden is only part of the equation, because they want to know how far north and south they can fly on a given day, making "yo-yo" flights following the eastern escarpment north and south as many times as they can in daylight. Several pilots are developing a whole theory of such flying, debating fine points of the techniques such as whether it is better to launch at the northern or southern end of the escarpment. This is an area of study that will probably not be answered soon as more and more pilots try their hand at some really special flying conditions.

As to the site record, Tony is the final authority on what has happened here. Our "records" board indicates a 37,000' flight in 2003, and another flight over Jack's Valley (at the northern end of the Carson Valley) in 1988 to 45,000'.