Mountain Wave

mw-1.JPG (17043 bytes)
Elias W. in front of AS-K 21, serious student
Wind is frontal right to rearward left in photo.
Typical late day lennies

Mountain Wave - Required Weather Conditions
  1. Wind at Mountaintop at 20 kts or more
  2. Wind Direction within 45 degrees of perpendicular to ridge line
  3. Wind Smoothly increasing with altitude, no direction change of more than 30 degrees
  4. More stable layer at mountaintop level between less stable layers at the surface and high aloft
Clouds Associated with Mountain Wave
Altocumulus Standing Lenticular Fractocumulus Stratocumulus
Lennies Rotor Clouds Cap Clouds

How to Find Smooth Area or How to Find Lift Area

  1. Determine wind aloft direction -- where’s upwind?
  2. If you’re in chop or turbulence, move upwind = closer to parallel mountain line, to find an area of smooth air.
    This may mean shifting parallel as much as a half-mile.
  3. This should place you in smooth lifting air. If you need to descend, move downwind of the turbulent area.

 How to Cross a Mountain Line During a Wave Condition
(for airplane drivers primarly, but glider folks, too)

Crossing Upwind

Climb for extra altitude in lift band prior to last mile headed upwind to the ridge. Be willing to add 2000 or 3000 ft. extra before crossing upwind, then spend the altitude in extra cruise speed as you pass upwind near the ridge. Cross at 90 degrees for shortest distance in the strong sinking air. Be willing to turn back downwind.

Crossing Downwind

Climb for extra altitude (1000-2000 ft) prior to crossing the mountain. You will find strong sink on the leeward edge (over the waterfall), keep speed up and sacrifice altitude to continue cruise speed. Watch VSI. When entering lift area – slow up a lot and recover your altitude. Work parallel to mtns. in lift band, climb OVER rotor and continue downwind.

Tell ATC you are experiencing mountain wave, and you will not be holding your cruise altitude while transitioning this area. Try to advise them of your intentions. They are there to serve you.

Wave Window Information

California City has two separate processes for flying in wave conditions. A different set of flight rules apply, depending on what the military users of our airspace are doing.

If the military users (DoD) are active, then we can only have access to airspace above FL180 by being a "joint user." This means we will be equipped with Mode C transponders, or we will operate one transponder glider with one non-transponder glider as a formation flight of two.This is the process that we use during Wave Camp, when we are scheduled as users jointly with the military above FL180. Wave Camp is scheduled for the first two weeks of March inclusive of three weekends. We have been historically "clean" users here for 10 years, and have updated the letter of agreement with the military to allow us year-round access as joint users, WITH TRANSPONDERS above FL 180.

Mountain Wave
Sunset typical lenticulars (lennies), looking WSW from Cal City.

For this letter of agreement, the flight area is called Wave Camp window. It is from California City Airport to Mojave Airport to Tehachapi Pass at Hwy 58 to the north east end of Lone Tree Canyon and return to California City.

When the military is not using, we can have access to larger different geographic areas with no transponder requirement for above FL180. You must have the ability for each glider to monitor ATC on 133.65 and comply with all ATC instructions, including "requests" to descend or cap off climb altitudes. There are three large glider areas that follow the bands of the Sierras stretching from Cal City to alongside Inyokern and on north to Lone Pine. These are called Glider One, Two and Three. There is nothing north of the north edge of Owens MOA.

North of Owens MOA the airspace responsibility shifts to FAA at Oakland Center. Due to the volume of airline activity around the end of Owens MOA, a window at Bishop is a very slim possibility, and does not currently exist. Also, Oakland Center hasn't been happy with PASCO and Minden's lack of effective management of their windows. Flights outside of windows, or without windows are big threats to the glider relationship with ATC for the long term, not to mention risks to your personal flight safety!  Don't jeopardize our future privileges.

The no-transponder operations require ATC to separate IFR (airline) traffic around the lateral boundaries or 2000-ft. over active glider wave windows. Additionally, there are few days that the Navy, Air Force or Army is NOT using the R-2508 airspace. (This is what prompted us to ask for "regular" joint use with transponders on a year-round basis.)