question: How do pilots know when to expect turbulence?
comment: Somebody will come around with a clearer answer, but I think pilots that have experienced unexpected turbulence just report it to ATC, and then ATC lets the other pilots know when they’re entering the area where turbulence was reported.
passages: BULLET::::- The pilot may issue a Pilot Report (PIREP), communicating position, altitude and severity of the turbulence to warn other aircraft entering the region.
  
  Section::::Effects on aircraft.:Cases.
   Section::::Sensors for NOE.
  
  Most NOE flying is done during the day using visual reference by pilots who are experienced in low flying. Data from a radar altimeter or terrain-following radar system is also used, the latter enabling low flying in adverse weather where it would not be possible by visual reference and manual pilot control. At night, a night-vision device may be used.
  
  Section::::Helicopter NOE flying.
   Weather systems such as weather radar (typically Arinc 708 on commercial aircraft) and lightning detectors are important for aircraft flying at night or in instrument meteorological conditions, where it is not possible for pilots to see the weather ahead. Heavy precipitation (as sensed by radar) or severe turbulence (as sensed by lightning activity) are both indications of strong convective activity and severe turbulence, and weather systems allow pilots to deviate around these areas.
   Detecting and predicting CAT is difficult. At typical heights where it occurs, the intensity and location cannot be determined precisely. However, because this turbulence affects long range aircraft that fly near the tropopause, CAT has been intensely studied. Several factors affect the likelihood of CAT. Often more than one factor is present. 64% of the non-light turbulences (not only CAT) are observed less than away from the core of a jet stream.
  
  Section::::Factors that increase CAT probability.:Jet stream.
   Section::::Hazard avoidance.:Staying on or above leader's glide path.
   As the result of the accidents due to wind shear and other weather disturbances, most notably the 1985 crash of Delta Air Lines Flight 191, the U.S. Federal Aviation Administration mandated that all commercial aircraft have on-board wind shear detection systems by 1993. Since 1995, the number of major civil aircraft accidents caused by wind shear has dropped to approximately one every ten years, due to the mandated on-board detection as well as the addition of Doppler weather radar units on the ground (NEXRAD). The installation of high-resolution Terminal Doppler Weather Radar stations at many U.S. airports that are commonly affected by wind shear has further aided the ability of pilots and ground controllers to avoid wind shear conditions.
   Clear-air turbulence is usually impossible to detect with the naked eye and very difficult to detect with a conventional radar, with the result that it is difficult for aircraft pilots to detect and avoid it. However, it can be remotely detected with instruments that can measure turbulence with optical techniques, such as scintillometers, Doppler LIDARs, or N-slit interferometers.
   When a pilot experiences CAT, a number of rules should be applied: 
  
  BULLET::::- The aircraft must sustain the recommended velocity for turbulence.
  
  BULLET::::- When following the jet stream to escape from the CAT, the aircraft must change altitude and/or heading.
  
  BULLET::::- When the CAT arrives from one side of the airplane, the pilot must observe the thermometer to determine whether the aircraft is above or below the jet stream and then move away from the tropopause.
  
  BULLET::::- When the CAT is associated with a sharp trough, the plane must go through the low-pressure region instead of around it.
   Following a checklist would have shown that the gust lock was engaged on the Gulfstream IV crash on May 31, 2014. The National Transportation Safety Board downloaded data from the aircraft's recorder and found it was a habit: 98% of the previous 175 takeoffs were made with incomplete flight-control checks. The National Business Aviation Association analyzed 143,756 flights in 2013-2015 by 379 business aircraft and only partial flight-control checks were done before 15.6% of the takeoffs and no checks at all on 2.03% of the flights.
  
  Section::::History.
   Section::::Effects on aircraft.:Wake turbulence.
   BULLET::::5. Excessive deviation below glideslope ("GLIDESLOPE")
  
  BULLET::::6. Excessively steep bank angle ("BANK ANGLE")
  
  BULLET::::7. Windshear protection ("WINDSHEAR")
  
  The traditional GPWS does have a blind spot. Since it can only gather data from directly below the aircraft, it must predict future terrain features. If there is a dramatic change in terrain, such as a steep slope, GPWS will not detect the aircraft closure rate until it is too late for evasive action.
   The Cockpit voice recorder (CVR) recorded normal cockpit conversation during the last minute of the flight. At 23:40:22 the co-pilot reported "You're a little high" and at 23:40:33 "You're at minimums." At 23:40:35 the first officer stated "Field in sight" then "Turn to your right" followed by "hundred and forty knots." No further conversation was recorded by the CVR.
   In response to questioning from the NTSB, Colgan Air officials acknowledged both pilots apparently were not paying close attention to the aircraft's instruments and did not properly follow the airline's procedures for handling an impending stall. "I believe Capt. Renslow did have intentions of landing safely at Buffalo, as well as first officer Shaw, but obviously in those last few moments ... the flight instruments were not being monitored, and that's an indication of a lack of situational awareness," said John Barrett, Colgan's director of flight standards.
   Because aircraft move so quickly, they can experience sudden unexpected accelerations or 'bumps' from turbulence, including CAT - as the aircraft rapidly cross invisible bodies of air which are moving vertically at many different speeds. Although the vast majority of cases of turbulence are harmless, in rare cases cabin crew and passengers on aircraft have been injured when tossed around inside an aircraft cabin during extreme turbulence (and in a small number of cases, killed, as on United Airlines Flight 826 on December 28, 1997). BOAC Flight 911 broke up in flight in 1966 after experiencing severe lee-wave turbulence just downwind of Mount Fuji, Japan.
   The updated flight control system will take input from both flight control computers and compare their outputs, rather than simply letting MCAS software read from two angle of attack sensors.
  
  Section::::Corrective work.:Flight simulator and training.
   BULLET::::- In the medical field of cardiology, a stethoscope is used to detect heart sounds and bruits, which are due to turbulent blood flow. In normal individuals, heart sounds are a product of turbulent flow as heart valves close. However, in some conditions turbulent flow can be audible due to other reasons, some of them pathological. For example, in advanced atherosclerosis, bruits (and therefore turbulent flow) can be heard in some vessels that have been narrowed by the disease process.
  
  BULLET::::- Recently, turbulence in porous media became a highly debated subject.
  
  Section::::Features.
  
  Turbulence is characterized by the following features:
   Wake turbulence can be measured using several techniques. Currently, ICAO recognizes two methods of measurement, sound tomography, and a high-resolution technique is Doppler lidar, a solution now commercially available. Techniques using optics can use the effect of turbulence on refractive index (optical turbulence) to measure the distortion of light that passes through the turbulent area and indicate the strength of that turbulence.
  
  Section::::Audibility.
   Glider pilots routinely practice flying in wingtip vortices when they do a maneuver called "boxing the wake." This involves descending from the higher to lower position behind a tow plane. This is followed by making a rectangular figure by holding the glider at high and low points away from the towing plane before coming back up through the vortices. (For safety this is not done below above the ground, and usually with an instructor present.) Given the relatively slow speeds and lightness of both aircraft the procedure is safe but does instill a sense of how strong and where the turbulence is located.
   CAT can be hazardous to the comfort, but rarely the safety, of air travelers.
  
  CAT in the jet stream is expected to become stronger and more frequent because of climate change, with transatlantic wintertime CAT increasing by 59% (light), 94% (moderate), and 149% (severe) by the time of CO2 doubling.
  
  Section::::Detection.
   The pilots discovered a throttle setting that would maintain a descent in level attitude, with airspeed maintained between 125 and 140 knots; the nose rose when power was increased and fell when power was decreased. Their rate of descent could be maintained at approximately 500 feet per minute.
   Since the implementation of CRM circa 1979, following the need for increased research on resource management by NASA, the aviation industry has seen tremendous evolution of the application of CRM training procedures. The applications of CRM has been developed in a series of generations: 
  
  BULLET::::- First generation: emphasized individual psychology and testing, where corrections could be made to behavior.
  
  BULLET::::- Second generation: featured a shift in focus to cockpit group dynamics.
  
  BULLET::::- Third evolution: diversification of scope and an emphasis on training crews in how they must function both in and out of the cockpit.
   VFR pilots primarily navigate by using the GPS, radio navigation systems, and most importantly pilotage. In order to perform pilotage, pilots must visually see the ground features and reference it to the map. Accidents are inevitable when flying into instrument meteorological conditions (IMC) without the proper instrument flight rules (IFR) equipments. In fact, over 19% of the general aviation crashes are caused from flying VFR in to IMC and 72% of these crashes are fatal.
   Section::::Onset of turbulence.
   Section::::Hazard avoidance.:Warning signs.
   During quasi-linear convective systems (QLCS), colloquially known as squall lines, the detection of mesovortices, which generate at 4,000 to 8,000 feet above ground level, is not always possible with SAILS cuts, as the base 0.5 degree scan travels below the formation of mesovortices at closer distances to the radar. Mid-Volume Rescan of Low-Level Elevations (MRLE) consecutively scans either the two, three or four lowest scan angles during the middle of a typical volume scan, allowing more frequent surveillance of mesovortex formation during QLCS events. MRLE will be deployed on a non-operational basis in RPG 18.0 in spring of 2018, with possible operational deployment with RPG 19.0, if proven useful or of importance.
  
presuppositions: Pilots know when to expect turbulence. Pilots know when to expect turbulence. Pilots know when to expect turbulence. Pilots know when to expect turbulence. Pilots know when to expect turbulence. Pilots know when to expect turbulence.
corrections: The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts.  The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts.  The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts.  The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts. The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts.  The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts. 
raw_presuppositions: Pilots know when to expect turbulence. Pilots know when to expect turbulence. Pilots know when to expect turbulence. Pilots know when to expect turbulence. Pilots know when to expect turbulence. Pilots know when to expect turbulence. Pilots know when to expect turbulence.
raw_corrections: The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts.  The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts.  The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts.  The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts. The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts.  The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircrafts.  The aircraft control center informs pilots when they enter an area where turbulence was already experienced and reported by other aircraft.