Advisory 

Circular

 

Subject: PREVENTING INJURIES 

CAUSED BY TURBULENCE 

Date: 1/19/06

Initiated by: AFS-200 

AC No: 120-88A 

1. Purpose. This AC provides information and practices that can be used to prevent injuries 

caused by turbulence. 

a. Overall, U.S. air carriers have a superb safety record - one that has improved over time 

and now ranks among the best in the world. Air carrier incidents are infrequent; accidents are 

rare; and the risk of injury or death associated with this mode of transportation is very low. In an 

effort to reduce the chances that someone might get injured in an aircraft encountering 

turbulence, the Federal Aviation Administration (FAA) and the FAA’s Government and industry 

partners in the Commercial Aviation Safety Team (CAST) developed the advisory material in 

this AC. Some of this material responds to investigative work and safety recommendations from 

the National Transportation Safety Board (NTSB). 

b. Each of those organizations has called for industry and government to come together to 

develop guidance to help aircraft operators avoid conditions that cause turbulence and to help 

aircraft operators minimize risks when aircraft encounter turbulence. Those organizations have 

further called for the FAA (1) to consolidate strategies and procedures known to be effective in 

preventing injuries caused by turbulence and (2) to issue guidance for implementation in the 

operations and training of air carrier flightcrews, flight attendants, aircraft dispatchers, and 

managers. This AC is the product of the work done by the CAST partners and by certain others 

working apart from CAST. 

2. Content of this AC. This AC highlights the data-driven methods of the FAA and its 

government and industry partners in identifying practices known to be effective against injuries 

caused by turbulence. Practices identified in the AC are suggested for crewmembers, aircraft 

dispatchers, managers, trainers, and others associated with flight operations under Title 14 of the 

Code of Federal Regulations (14 CFR) part 121. Those practices are suggested components of 

standard operating procedures that can be followed in daily flight operations and continually 

reinforced in training. 

3. Related FAA guidance. This AC provides suggested measures for preventing injuries 

caused by turbulence and expands upon existing guidance including:

• Airplane Upset Recovery Training Aid, available at the following FAA public web site: 

 (http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/index.cfm) 
AC 120-88A 1/19/06 

Page 2 Par 3 

• AC 00-30B, Atmospheric Turbulence Avoidance 

(http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf) 

• FAA Turbulence Information Website 

(http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/turbulence) 

4. Related Regulations. 14 CFR part 121, sections 121.311, 121.317, 121.417, 121.421, 

121.427, part 125, sections 125.211, 125.217, 125.287, 125.289, part 135, sections 135.117, 

135.128, 135.331, 135.349, 135.351; Title 49 of the Code of Federal Regulations (49 CFR) part 

830, section 830.2. These regulations are available on line at: 

http://www.gpoaccess.gov/cfr/index.html

5. Who should read this AC. Managers, trainers, flightcrew (pilots and flight engineers), flight 

attendants, aircraft dispatchers, and others involved in flight operations under 14 CFR part 121 

should be familiar with the contents of this AC. This AC may also be valuable to persons 

associated with operations under part 125, part 135, subpart K of part 91 (fractional ownership 

programs), and part 91. 

6. What the available data tells us about injuries caused by turbulence. 

a. Definitions. 

(1) Accident. The NTSB defines an “accident” in 49 CFR section 830.2 as “an 

occurrence associated with the operation of an aircraft which takes place between the time any 

person boards the aircraft with the intention of flight and all such persons have disembarked, and 

in which any person suffers death or serious injury, or in which the aircraft receives substantial 

damage.” 

(2) Fatal injury. The NTSB defines a fatal injury as “any injury that results in death 

within 30 days of the accident.”

(3) Serious injury. The NTSB defines serious injury as “Any injury that (1) requires 

the individual to be hospitalized for more than 48 hours, commencing within 7 days from the 

date the injury was received; (2) results in a fracture of any bone (except simple fractures of 

fingers, toes, or nose); (3) causes severe hemorrhages, nerve, muscle, or tendon damage; (4) 

involves any internal organ; or (5) involves second- or third-degree burns, or any burns affecting 

more than 5% of the body surface. 

(4) Minor injury. Any injury that is neither fatal nor serious. 

b. Data Analysis by the FAA: Sit down and buckle up. The data strongly suggest that 

an effective measure during a turbulence encounter is to have passengers and flight attendants 

seated with seatbelts fastened. From 1980-2003, only four people received serious injuries 

during turbulence who were seated with seatbelts fastened (excludes cases of other people falling 
1/19/06 AC 120-88A 

Par 6 Page 3 

onto and injuring properly secured occupants). Graphical depictions of these data are contained 

in Appendix 5. 

7. How an air carrier can design effective training to prevent or mitigate injuries to flight 

attendants caused by turbulence. 

a. Take advantage of the training environment. The training environment presents an 

excellent opportunity to train crewmembers in an air carrier’s standard operating procedures 

including standard phraseology, and to introduce concepts that might promote crewmembers’ 

adherence to those procedures during a turbulence encounter. The training environment for 

flight attendants and flightcrew affords a unique opportunity for lectures, scenarios and exercises 

designed to explore subjects such as evaluating risk, good and bad decisionmaking and the 

importance of crew coordination before, during and after a turbulence encounter. 

b. Emphasize the importance of flight attendants’ personal safety. Flight attendant 

injuries occur at a disproportionately high rate compared to other crewmembers and other cabin 

occupants because flight attendants spend more time in the passenger cabin unseated and, 

therefore, unbelted. Effective training emphasizes to flight attendants that: 

(1) You are not invincible. The overlying objective throughout all flight attendant 

training is to ensure that flight attendants are confident, competent, and in control while 

conducting their activities in the cabin. However, during a turbulence encounter, the most 

appropriate first response by a flight attendant might be self preservation. Training courseware 

can make flight attendants aware of their vulnerability in moderate and extreme turbulence. 

Effective training can incorporate video/digital media, real world scenarios and interviews with 

flight attendants who have experienced moderate and severe turbulence as a way to demonstrate 

that “turbulence can be stronger than you are.” 

(2) You have tools available to increase your safety and the safety of your 

passengers. Effective training shows flight attendants how to increase personal safety and 

passenger safety by identifying tools available to them in a turbulence encounter. Training can 

include the effective use of the passenger address system (PA) and other methods of 

communicating with passengers; the location of handholds throughout the airplane (or 

equipment that could be used as a handhold); and how to secure a service cart or an entire galley 

in minimum time. 

(3) You need to recognize and avoid a denial reflex. Flight attendants can be made 

aware of ways in which human psychology might play into a turbulence encounter, and might 

actually increase their risk of injury. For example, on a short flight, with little time to complete a 

cabin service, flight attendants might be less conservative regarding their personal safety than on 

a longer flight with no time constraints. Flight attendants can also increase risk and compromise 

their personal safety by trying to adhere to routine procedures normally accomplished on every 

flight, such as completing seatbelt compliance checks, rather than by responding to the 

nonroutine situation that a turbulence encounter presents. 
AC 120-88A 1/19/06 

Page 4 Par 7 

c. Promote communication and coordination. Crew resource management (CRM) 

training for crewmembers and dispatch resource management (DRM) training for aircraft 

dispatchers can emphasize that the individual is part of a team. 

(1) Address turbulence response in CRM training. Communication and coordination 

among crewmembers is a critical component of an effective response to turbulence or a threat of 

turbulence. Air carriers can develop and implement CRM training in Initial and Recurrent 

crewmember training that encourages a coordinated crew response before, during and after a 

turbulence encounter. 

(2) Subtopics supporting CRM and DRM training to counter turbulence. Effective 

and ineffective team performance can be made clearer by addressing topics such as: 

• The importance of using standard phraseology so that meaning and intent are 

never in doubt 

• The importance of using standard operating procedures (SOPs) so that all 

crewmembers know what to expect 

• The importance of an effective preflight briefing that can include: 

 - Potential of turbulence encounters during each leg 

 - Emphasis on the importance of keeping the flight deck informed of the 

conditions in the cabin 

 - Commitment to using standard air carrier procedures and phraseology during a 

turbulence encounter 

• The importance of maintaining communication during the flight, including 

communication with the aircraft dispatcher, as appropriate 

• The results of communication errors such as the use of vague, inaccurate 

descriptions and nonstandard phraseology regarding turbulence 

NOTE: It is highly desirable to conduct joint CRM training including 

flightcrew, flight attendants, and aircraft dispatchers. However, if joint 

training is not practical, each of these training populations can be made 

aware of the others’ functions regarding turbulence through other training 

methods. 

8. Operating procedures an air carrier can implement to prevent injuries caused by 

turbulence. 

a. Crewmembers. Appendix 1, CAST’s Turbulence Template, contains suggested 

procedures for crewmembers developed by a broad collaboration of Government and industry 

representatives under CAST. 
1/19/06 AC 120-88A 

Par 8 Page 5 

b. Passengers. Procedures promoting voluntary seatbelt use and compliance with the 

Fasten Seatbelt sign, can include the following: 

• Flightcrew promptly and clearly communicate turbulence advisories 

including specific directions to flight attendants and to passengers. Those 

advisories can include directions to be seated with seatbelts fastened, and to 

secure cabin service equipment, as conditions may require

• Flight attendants effectively communicate directions to passengers to be 

seated with seatbelts fastened

• Air carriers develop and implement practices to encourage the use of an 

approved child restraint system (CRS) to secure an infant or a small child that 

is appropriate for that child’s size and weight

− Parents and guardians can be encouraged to ensure that children under the age 

of two, traveling with approved CRS, occupy the CRS any time the Fasten 

Seatbelt sign is illuminated 

− Flight attendants can verify that the CRS is secured properly in a forward 

facing seat and that the child appears to be properly secured in the CRS 

• Air carriers develop and implement practices to improve passenger compliance 

with seating and seatbelt instructions from crewmembers such as: 

− Video presentations incorporated as part of a flight attendant’s safety 

demonstration can illustrate the benefits of using effective turbulence 

practices 

− Articles in airline publications, pamphlets in seat back pockets or 

information on safety information cards can encourage passengers to 

engage in effective practices such as keeping seatbelts fastened at all times 

− Before descent, or early in the descent, depending on conditions, flightcrews 

may give passengers notice by way of an announcement that the Fasten 

Seatbelt sign will be illuminated in 10-15 minutes, and that any personal 

needs requiring movement in the cabin should be met before that time. This 

practice emphasizes the requirement to comply with the Fasten Seatbelt sign 

• Air carriers can implement spoken and written advice to passengers that FAA 

regulations require them as individuals to comply with crewmember 

instructions regarding the Fasten Seatbelt sign 

• Air carriers can promote reasonable communication between flight attendants 

and the flightcrew regarding the use of the Fasten Seatbelt Sign 

− The environment in the cabin may be very different from the environment in 

the flight deck during turbulence. Flight attendants should feel free to request 

that the flightcrew illuminate the Fasten Seatbelt sign whenever it is 

appropriate to do so in their judgment 
AC 120-88A 1/19/06 

Page 6 Par 7 

− Conversely, when the Fasten Seatbelt sign remains illuminated for prolonged 

periods of time for reasons other than protection from a turbulence encounter, 
1/19/06 AC 120-88A 

Par 10 Page 7 

its effectiveness can diminish for passengers and flight attendants. Flight 

attendants should feel free to question the flightcrew regarding the necessity 

of having the Fasten Seatbelt sign illuminated 

9. What else an air carrier can do to prevent injuries caused by turbulence. 

a. Review its own history of turbulence encounters and injuries. Volunteers representing 

various stakeholder groups within an air carrier may work together as a highly competent team. 

The team can review the air carrier’s own turbulence encounters and resulting injuries. That 

review might shed light on root causes of the encounters and the injuries, and, in turn, might 

show the way to effectively prevent them. 

b. Gather current information on turbulence encounters and injuries. Current 

information is generated in a variety of ways such as turbulence reports from crewmembers, 

injury reports from flight attendants, postencounter interviews and other processes that provide 

information for review and analysis. 

c. Information useful for analysis can include: 

(1) Length of flight. 

(2) Route of flight. 

(3) Time of year. 

(4) Phase of flight. 

(5) Aircraft type. 

(6) Type of injuries received by passengers. 

(7) Type of injuries received by crewmembers. 

(8) Adequacy of crewmember communications. 

(9) Adequacy of air carrier procedures. 

10. Cabin modifications, such as hand holds, restraints, or other devices, an air carrier can 

consider to reduce injuries caused by turbulence. When an aircraft encounters unanticipated 

turbulence there may not be time for preparation by crewmembers or passengers. In this 

situation, measures most likely to prevent or mitigate injuries caused by turbulence involve 

aircraft design. Effective aircraft design features promote the following:

• Interior restraints and overhead bin doors can prevent equipment failures during 

turbulence 
AC 120-88A 1/19/06 

Page 8 Par 8 

• Cabin structures with hard or angular surfaces, corners, or protrusions can be 

minimized 

• Emergency handholds can be readily identifiable and usable in the cabin, galley and 

lavatories (such as handles, bars, or interior wall cut outs) by flight attendants and 

passengers who are not seated with seatbelts fastened 

• Handrails and/or handgrips can be installed under the overhead compartments in the 

cabin 

• Horizontal and vertical “grab bars” can be installed on the counters and stowage 

compartments in galleys 

• In configurations where seats are distributed with a large pitch and the seat backs 

can be reclined to an almost flat position, air carriers can install supplemental 

handholds beside the seats or install partitions around the seats to provide a 

handhold if the seat is fully reclined 

• Handholds can be installed outside the lavatories on the bulkhead walls for use by 

passengers who may be standing outside the lavatory at the onset of a turbulence 

encounter 

11. Improvements in dispatch procedures an air carrier can implement to prevent injuries 

caused by turbulence. 

a. Keep communication channels open full-time. Dispatchers can communicate with 

flightcrews, and flightcrews can communicate with dispatchers, before, during, and after a flight, 

and can be encouraged to do so whenever necessary. In the preflight planning phase, the 

dispatcher may use the “Remarks” section of the dispatch (flight) release to advise flightcrews of 

known or forecast turbulence. A “call dispatch” notation on the dispatch release may be 

included to indicate that the dispatcher believes a telephone conversation with the pilot is 

necessary. Communication may resume at any time during or after flight using an Aircraft 

Communication Addressing and Recording System (ACARS), company radio, or telephone – 

and should be encouraged by an air carrier’s management to improve the flow of real-time 

information regarding turbulence. 

b. Weather Briefings. Preflight weather briefings, verbal or written, must include 

forecasts of turbulence and pilot reports of turbulence caused by thunderstorm activity, mountain 

wave activity, clear air turbulence, low altitude frontal windshear and low altitude convective 

windshear. 

c. Real-time Information Sharing. During a flight, the pilot and dispatcher must 

communicate any changes in the forecast or actual turbulence conditions via voice or digital 

communication methods in order to pass real-time turbulence information along to other flights. 
1/19/06 AC 120-88A 

Par 14 Page 9 

12. Elements an air carrier can integrate into aircraft dispatcher training to prevent 

injuries caused by turbulence. 

a. New products and services. Dispatcher training can include new weather products 

and services available from private vendors as well as those provided by the National Weather 

Service. 

b. Continual reinforcement of the air carrier’s turbulence avoidance policy can be 

evident in theory, in on-the-job training, and in practice. 

• Assure pilot weather briefing includes known areas of turbulence 

• Discuss flight routing, including en route altitudes, with flightcrew prior to 

departure 

• Plan flights so they will not proceed through areas in which thunderstorms of 

more than moderate intensity are known to exist 

• Add remarks to dispatch/flight release or weather briefing to emphasize areas 

where turbulence may be expected 

• Plan flights to avoid areas of severe turbulence 

• Plan flights to avoid areas with severe thunderstorms 

• Add remarks to dispatch/flight release to emphasize areas of turbulence that can 

be avoided 

13. Three fundamentals of effective practices against turbulence. 

a. Turbulence Avoidance as corporate culture. The first and most fundamental step in 

developing effective practices is that an air carrier can adopt a corporate culture of avoidance of 

turbulence as the first line of defense. Implementing a turbulence avoidance culture can include 

standard operating procedures (SOPs) for dispatch and flight operations providing for rerouting 

around forecast and observed turbulence, and for observing standard clearances between 

thunderstorms and aircraft. 

b. Rerouting. In the past the practice of rerouting has met with limited air carrier 

acceptance, primarily because of the inaccuracy of first generation turbulence forecast products, 

the subjectivity inherent in Pilot Weather Reports (PIREP) (if available), and the operational 

costs of rerouting. However, recent advances in automation, atmospheric modeling, and data 

display have improved forecast accuracy, data delivery, and PIREP subjectivity, improving the 

odds that a well-chosen rerouting would in fact avoid turbulence. 

c. Standard clearances between thunderstorms and aircraft. See Appendix 2. 
AC 120-88A 1/19/06 

Page 10 Par 12 

14. Other effective practices that can be used by managers, trainers, meteorologists, and 

aircraft dispatchers. Effective practices can include:

• Use all applicable weather data and products including alphanumeric weather 

information such as Aviation Routine Weather Reports (METARS), area forecasts 

and terminal area forecasts (TAFs), wind and temperature forecasts, National 

Weather Service (NWS) in-flight advisories such as Significant Meteorological 

Advisories (SIGMETS), Convective SIGMETS and Airman’s Meteorological 

Information (AIRMETS), upper air charts, graphical radar summaries or composites, 

and satellite imagery 

• Use sophisticated product generation to merge diverse sources into graphical product 

to track turbulence 

• Compile turbulence information, including PIREPs, making relevant information 

easily usable to dispatchers, flightcrews, and air traffic controllers 

15. New systems of turbulence reporting and forecasting developed since AC 00-30B was 

issued in 1997. There have been significant improvements in turbulence reporting and 

forecasting. Since 1997, major advances in data processing and delivery have allowed graphical 

depictions of weather to be delivered in near real-time, even to the flight decks of suitably 

equipped aircraft. Advanced reporting, forecasting, and delivery of graphics have been 

promoted by government/industry partnerships and by the leadership of various organizations 

including the FAA’s program office for Aviation Weather Research. Some of the most 

promising advances are shown in Appendix 3 (Detection) and Appendix 4 (Delivery).

16. Additional steps air carriers can take to avoid turbulence and thereby prevent cabin 

injuries. 

a. Real-time information, airplane-to-ground. Continued improvement in turbulencerelated weather products requires better handling of real-time information on the state of the 

atmosphere at any given time. The most promising way to capture and convey this information 

is through a comprehensive program of reports from aircraft in flight. That program would be 

founded on automated turbulence reporting supplemented by human reports (PIREPs). Air 

carriers can promote real-time information handling by the following steps: 

(1) Commit to the installation of the Turbulence Auto-PIREP System (TAPS). TAPS 

is being developed under the NASA Turbulence Prediction & Warning System (TPAWS) 

program. This system generates real-time, automatic reports of hazardous turbulence events, and 

displays the information for improved operations around turbulence. The reports quantify the 

severity of the loads experienced in the aircraft’s cabin in accordance with the standard levels of 

light, moderate, severe, and extreme as described in the FAA’s Aeronautical Information Manual 

(AIM). These downlinked reports are displayed on dispatchers’ flight-following display 

network, and can be scaled and used to predict and inform other aircraft of potential turbulence 

encounter severity. Reports are only generated whenever significant turbulence events are 

encountered. Future efforts will develop the capability to broadcast the reports from aircraft-toaircraft and display the reports in the flight deck. 
1/19/06 AC 120-88A 

Par 17 Page 11 (and 12) 

(2) Operators of regional, commuter and smaller cargo-only aircraft may commit to 

installation of Tropospheric Aircraft Meteorological Data Reporting (TAMDAR) weather 

reporting systems on company aircraft. The TAMDAR system has been developed under NASA 

contract. TAMDAR is designed as a small, lightweight weather data sensor package and 

downlink system, primarily for use by smaller aircraft that operate below FL200. The 

TAMDAR data set includes automated turbulence reporting in terms of eddy dissipation rate 

(EDR; see Appendix 3), in addition to other atmospheric weather markers (winds, temperatures, 

relative humidity, etc.). 

(3) Improve the coverage and objectivity of atmospheric turbulence reports by 

installation of automated aircraft turbulence downlink systems on all ACARS equipped aircraft. 

(The current International Civil Aviation Organization (ICAO) standard metric for automated 

turbulence reporting is EDR). 

(4) Encourage additional reporting of PIREPs by flightcrews through air carrier PIREP 

awareness campaigns and by training flightcrews to follow established PIREP procedures. 

(5) Establish communications links and encourage flightcrews to deliver air carrier 

“in-house” PIREPs to the National Weather Service (NWS) and to the FAA using Flight Watch. 

b. Efficient delivery of current information, ground-to-airplane. In conjunction with 

improved turbulence reporting airplane-to-ground, air carriers may join with other industry 

groups and with government organizations to develop faster processing and delivery of current 

turbulence information ground-to-airplane. Work can be done in at least the following areas: 

(1) Conducting an assessment of communications/processing/distribution systems for 

gridded, alphanumeric, and graphical image turbulence information exchange in the National 

Airspace System (NAS) in order to determine necessary improvements; 

(2) Developing a plan to integrate required improvements in conjunction with normal 

upgrade/replacement cycles for ground-to-ground and ground-to-air systems, and/or a costeffective mix of Internet, Intranet and other evolving communications systems; 

(3) Developing a tailored “forced” uplink of critical alpha/numeric reports and 

forecasts to existing displays on the flight deck, and follow up with a comparable graphic 

product to take advantage of evolving flight deck display technology. 

17. Actions air carriers can take to support emerging technologies. Air carriers support 

development and implementation of emerging technologies when they:

• Retrofit current predictive wind shear equipped aircraft with enhanced turbulence 

detection radar 

• Assist in certification of enhanced radar 

• Conduct inservice flight trials to determine the effectiveness of new onboard radar 
AC 120-88A 1/19/06 

Page 12 Par 16 

systems in detecting turbulence, and the feasibility of using them 

• Consider graphical onboard turbulence display systems 

• Work with FAA, NASA, and other Government organizations, and with equipment 

manufacturers to develop industry standard weather formats for flight deck display 

systems (carry-on and new production panel mounted) 

ORIGINAL SIGNED BY 

JOHN M. ALLEN (for) 

James J. Ballough 

Director, Flight Standards Service 
1/19/06 AC 120-88A 

 Appendix 1 

 Page 1 

APPENDIX 1. COMMERCIAL AVIATION SAFETY TEAM (CAST) 

TURBULENCE TEMPLATE

The CAST Turbulence Template comprises two parts: 

STANDARD TERMINOLOGY FOR TURBULENCE, endorsed by the Commercial Aviation 

Safety Team, from the Aeronautical Information Manual (AIM) 

PROCEDURES KNOWN TO BE EFFECTIVE AGAINST TURBULENCE, procedures 

identified by the Commercial Aviation Safety Team and suggested as standard operating 

procedures for voluntary implementation by U.S. air carriers 

STANDARD TERMINOLOGY FOR TURBULENCE 

The following terminology is endorsed by the Commercial Aviation Safety Team, from the 

Aeronautical Information Manual 

(http://www.faa.gov/atpubs/) 

DURATION OF TURBULENCE 

Occasional. Less than 1/3 of the time. 

Intermittent. 1/3 to 2/3 of the time. 

Continuous. More than 2/3 of the time. 

NOTE: Duration may be based on time between two locations or over a 

single location. All locations should be readily identifiable.

TURBULENCE INTENSITY 

Light Chop. Slight, rapid, and somewhat rhythmic bumpiness without appreciable 

changes in altitude or attitude. 

Light Turbulence. Slight, erratic changes in altitude and/or attitude. Occupants may 

feel a slight strain against seatbelts. Unsecured objects may be displaced slightly. Food 

service may be conducted and little to no difficulty is encountered in walking. 

Moderate Chop. Rapid bumps or jolts without appreciable changes in aircraft altitude 

or attitude. 

Moderate Turbulence. Changes in altitude and/or attitude occur but the aircraft remains 

in positive control at all times. It usually causes variations in indicated airspeed. 
AC 120-88A 1/19/06 

Appendix 1 

Page 2 

APPENDIX 1. COMMERCIAL AVIATION SAFETY TEAM (CAST) 

TURBULENCE TEMPLATE (Continued) 

Occupants feel definite strain against seatbelts. Unsecured objects are dislodged. Food 

service and walking are difficult.

Severe. Large, abrupt changes in altitude and/or attitude. Usually causes large 

variations in indicated airspeed. Aircraft may be momentarily out of control. Occupants 

are forced violently against seatbelts. Unsecured objects are tossed about. Food service 

and walking are impossible. 

Extreme. Aircraft is violently tossed about and is practically impossible to control. May 

cause structural damage.

TURBULENCE TYPES 

Thunderstorm Turbulence. Turbulence associated within and in the vicinity of 

thunderstorms or cumulonimbus clouds. A cumulonimbus cloud with hanging 

protuberances is usually indicative of severe turbulence. 

Clear Air Turbulence. High level turbulence (above 15000’) not normally associated 

with cumuliform cloudiness. Typically windshear turbulence even when in cirrus clouds. 

Mountain Wave Turbulence. Turbulence as a result of air being blown over a 

mountain range or a sharp bluff causing a series of updrafts and downdrafts. 

PROCEDURES KNOWN TO BE EFFECTIVE AGAINST 

TURBULENCE 

The following procedures have been identified by the CAST and are suggested as standard 

operating procedures for voluntary implementation by U.S. air carriers 

MAXIMIZE THE INFORMATION ABOUT YOUR FLIGHT CONDITIONS 

Inform ATC of turbulence at check in with new controller. 

Inform ATC when unforecasted turbulence is encountered en route. 

Inform company via ACARS or dispatch frequency so that following flights will be 

aware of the flight conditions or be planned on another route. 

Inform/query other aircraft operating in the area on a common frequency. 

Query ATC about “the rides” when you check in with a new controller/sector. 
1/19/06 AC 120-88A 

 Appendix 1 

 Page 3 

APPENDIX 1. COMMERCIAL AVIATION SAFETY TEAM (CAST) 

TURBULENCE TEMPLATE (Continued)

WHEN INFORMED OF TURBULENT FLIGHT CONDITIONS: 

Prior to departure, seek alternate routing to avoid the affected areas or delay departure 

until conditions improve. 

Change en route altitudes or routes to avoid the turbulence. 

Slow to the manufacturer’s recommended turbulence penetration speed. 

Prior to descent, seek alternate routing to avoid the affected areas or, if severity dictates, 

hold or divert to alternate. 

AVOID any convective activity (CBs) en route by at least 20 nautical miles. 

GENERAL TURBULENCE PROCEDURES 

If flight into forecast turbulence is unavoidable, timely notification to the cabin crew is 

crucial to their safety. 

If turbulence is expected before the flight departs, the preflight briefing to the lead flight 

attendant must include turbulence considerations. The briefing can be the same as an inflight briefing for expected turbulence including: 

• Actions the captain wants the cabin crew to undertake any time turbulence is 

expected 

• Intensity of turbulence expected 

• Methodology for communicating to the cabin the onset or worsening of turbulence, 

e.g., cabin interphone or PA 

• Phraseology for the cabin crew to communicate the severity of turbulence 

• Expected duration of the turbulence and how an “all-clear” will be communicated 

Utilize a positive signal of when cabin crew may commence their duties after takeoff and 

when they should be seated and secured prior to landing. 

Passengers will be informed of routine turbulence via the PA system. Do not rely on the 

seatbelt sign alone. 

Cabin crew will be informed of routine turbulence via the interphone. 

If at any time the cabin crew experiences uncomfortable turbulence without notice from 

the flight crew, they must immediately take their seats and inform the flight crew. 

All service items must be properly stowed and secured when not in use. 
AC 120-88A 1/19/06 

Appendix 1 

Page 4 

APPENDIX 1. COMMERCIAL AVIATION SAFETY TEAM (CAST) 

TURBULENCE TEMPLATE (Continued)

TURBULENCE ONSET CATEGORIES 

Expected Turbulence. Advance notice exists for the Captain to brief the cabin crew 

either prior to the flight or in-flight via the interphone. 

Little Warning. Sufficient warning exists to seat the passengers and for the cabin crew 

to perform their duties. 

Imminent Turbulence or Turbulence Occurring. Sudden, unexpected or imminent 

turbulence requiring immediate action to protect cabin crew and passengers. 

INJURY AVOIDANCE ACTIONS 

Expected Turbulence

Captain can thoroughly brief the cabin crew on the expected turbulence level and its 

duration. 

Clearly articulate expectations from the cabin crew and request confirmation of 

completed actions. 

Instruct the cabin crew to immediately and plainly report any deviations from the 

expected turbulence level. 

Develop a method to inform the cabin crew of the completion of the turbulence event. 

Little Warning

Captain turns on seatbelt sign and makes a public address announcement, ”Flight 

Attendants stow your service items and take your seats. Passengers please remain seated 

until this area of turbulence has passed and I have cleared you to move about the cabin.” 

Cabin crew stows all applicable service items, performs cabin compliance check, and 

secures themselves in their jump seats. 

Lead flight attendant informs captain of the completion of these items. 

When conditions improve, captain uses the public address system to advise the cabin 

crew that they may resume their duties and whether or not the passengers may move 

about the cabin.
1/19/06 AC 120-88A 

 Appendix 1 

 Page 5 (and 6) 

APPENDIX 1. COMMERCIAL AVIATION SAFETY TEAM (CAST) 

TURBULENCE TEMPLATE (Continued)

Imminent Turbulence or Turbulence Occurring 

Captain turns on seatbelt sign and makes a public address announcement, “flight 

attendants and passengers be seated immediately. Passengers please remain seated until 

this area of turbulence has passed and I have cleared you to move about the cabin.” 

Cabin crew take first available seat and secure themselves. 

No compliance checks are performed and items are secured only if they present no delay 

in securing a person in a seat. 

When conditions improve, captain makes public address announcement advising the 

cabin crew that they may resume their duties and whether or not the passengers may 

move about the cabin. 

1/19/06 AC 120-88A 

 Appendix 2 

 Page 1 (and 2) 

APPENDIX 2. USAF PRACTICES TO AVOID THUNDERSTORMS AND 

ATTENDANT TURBULENCE

The practices shown below are excerpted from United States Air Force Flight Publications for 

pilots of the Air Mobility Command (AMC). 

Many of the airplanes operated by AMC compare closely to the transport category airplanes 

operated by U.S. air carriers under 14 CFR part 121 in respect to size, weight, and other 

characteristics. Practices effective in AMC operations are often effective in commercial (air 

carrier) operations, and vice versa. 

The following practices have been developed by the Air Force for AMC pilots as measures to 

prevent thunderstorm penetrations and to mitigate effects of proximate thunderstorms, especially 

loss of control and turbulence that might cause injury. 

These practices are reprinted here for reference by managers and trainers of pilots operating 

transport category airplanes in commercial aviation, especially those carrying passengers and 

flight attendants under 14 CFR part 121. These practices are comprised of clear and objective 

criteria to facilitate recognition of cues associated with severe convective activity and guidance to 

improve flight crew decision-making. 

During flight, use any means available to avoid thunderstorms by at least: 

 20 nautical miles at or above flight level (FL) 230 

 10 nautical miles below FL 230 

In order to minimize exposure to thunderstorm hazards when approaching or departing an 

airport in an area where thunderstorms are occurring or are forecast; 

Attempt to maintain visual meteorological conditions (VMC). 

Maintain at least 5 nautical miles separation from heavy rain showers. 

Avoid areas of high lightning potential, i.e., clouds within ± 5,000 feet of the freezing 

level. 

NOTE: Approaches or departures may be accomplished when 

thunderstorms are within 10 nautical miles. The thunderstorms must 

not be producing hazardous conditions (such as hail, lightning, strong 

winds, gust fronts, heavy rain wind shear, or microburst) at the airport, 

and must not be forecast or observed to be moving in the direction of 

the route of flight (to include the planned missed approach corridor, if 

applicable).

1/19/06 AC 120-88A 

 Appendix 3 

 Page 1 

APPENDIX 3. DETECTION: NEW AND EMERGING TECHNOLOGIES, 

PRODUCTS AND SERVICES TO DETECT TURBULENCE 

(1) Turbulence Prediction and Warning systems (TPAWS). Currently NASA and 

FAA are leading a multi-disciplined Government/industry team directed at developing the 

scientific basis, algorithms and performance requirements for the detection of convective and 

non-convective related turbulence (http://tpaws.larc.nasa.gov). TPAWS efforts are focused on 

two areas: 

• Enhancements to existing aircraft radar systems – this includes new signal 

processing algorithms and alerting capabilities for predictive wind shear radars. 

The goal is to improve convective turbulence detection in the 25-40 mile range 

and deliver meaningful alerts to the crew 

• New onboard turbulence detection/mitigation technologies – this includes 

research into look-ahead detection systems such as Light Detection and Ranging 

(LIDAR), and automated flight control systems to mitigate turbulence initiated 

cabin accelerations 

NOTE: NASA and FAA are jointly conducting workshops for developing 

performance and certification criteria for development of turbulence 

sensors. 

(2) MDCRS (Meteorological Data Collection and Reporting System) – The goal 

of the MDCRS program is to significantly increase the availability of automated aircraft weather 

reports. MDCRS is the result of collaboration between the FAA, NWS, and six participating 

U.S. air carriers. Currently, MDCRS provides over 100,000 daily-automated aircraft wind and 

temperature reports to the FAA and NWS. 

(3) EDR (Eddy Dissipation Rate) – As part of the FAA Turbulence Product 

Development Team (PDT), the National Center for Atmospheric Research (NCAR) has 

developed the technology to use existing aircraft performance systems to derive an automated 

turbulence measurement (EDR). In collaboration with the FAA and NCAR, one airline has 

installed EDR software on over 100 aircraft. Since 2001, these 100 aircraft have been providing 

automatic downlink of peak and average turbulence readings at one-minute intervals. This 

information is currently being used for research and as input into automated turbulence forecasts 

(see GTG below). Future plans include installation of EDR software on as many as 1200 

commercial aircraft, converting the metric into aircraft specific ride reports, and distribution of 

this information nationally. 
AC 120-88A 1/19/06 

Appendix 3 

Page 2 

APPENDIX 3. DETECTION: NEW AND EMERGING TECHNOLOGIES, 

PRODUCTS AND SERVICES TO DETECT TURBULENCE (Continued) 

(4) GTG (Graphic Turbulence Guidance) – MDCRS and EDR aircraft reports are 

being used to update forecast models (RUC and GFS), as well as being used to develop 

automated turbulence forecast products, such as the newly developed Graphic Turbulence 

Guidance (GTG). The GTG has been under development for several years by NCAR. The GTG 

provides a graphic depiction of clear air turbulence potential for altitudes above FL200, over the 

contiguous U.S. at 3-hour intervals out to 12 hours. This product is available on the FAA funded 

Aviation Digital Data Service (ADDS) web site hosted by the NWS Aviation Weather Center 

(http://adds.aviationweather.noaa.gov/). 

(5) OCND (Ocean Convective Nowcast Demonstration) – Convection over oceanic 

areas has been and continues to be a major source of air carrier turbulence encounters and related 

injuries. This issue is being addressed by the FAA Oceanic Weather Product Development 

Team (OWPDT). As OWPDT members, NCAR and the Naval Research Lab (NRL) have 

developed an experimental graphic oceanic convective product, the Oceanic Convective 

Nowcast Demonstration (OCND). Using real time oceanic satellite data and associated analysis 

algorithms, convective cloud top graphics are generated at 30-minute intervals. During initial 

development the OCND graphic was available to dispatchers and oceanic controllers via 

Internet, and also uplinked to aircraft in flight over the central and south Pacific. Currently, 

experimental OCND products are available for the Pacific and Caribbean, with plans to expand 

coverage to include the North Atlantic in the near future. These graphics are available on an 

NCAR web site: (http://www.rap.ucar.edu/projects/owpdt). 

(6) CIWS (Center Integrated Weather System) - CIWS is an FAA sponsored 

program to develop an improved aviation convective weather graphic. CIWS uses radar inputs 

from NWS Next Generation Weather Radar (NEXRAD), FAA Terminal Doppler Weather Radar 

(TDWR), and FAA Airport Surveillance Radar (ASR) radars, to generate automated, high update 

information on storm locations and echo tops along with 2-hour high resolution animated growth 

and decay forecasts of storms. Coverage is limited to the Great Lakes and northeast corridor 

(Chicago to the East Coast). Airline systems operations centers had access to the products via 

servers on the Internet and CDM-Net as well as via dedicated displays. 

(7) ADDS (Aviation Digital Data Service) – ADDS is an operational FAA/NWS 

web site dedicated to providing graphic aviation products in real time. Developed by NOAA’s 

Forecast Systems Lab (FSL) under FAA sponsorship, the site includes leading edge products 

such as GTG and the NCWF, as well as traditional aviation products such as SIGMETS and 

convective SIGMETS in graphic format. Many of the available products provide critical 

information on turbulence (pilot reports, forecasts, convective products, SIGMETS, etc.) in 

graphic form. (http://adds.aviationweather.noaa.gov/). 

APPENDIX 3. DETECTION: NEW AND EMERGING TECHNOLOGIES, 
1/19/06 AC 120-88A 

 Appendix 3 

 Page 3 (and 4) 

PRODUCTS AND SERVICES TO DETECT TURBULENCE (Continued)

(8) NCWF (National Convective Weather Forecast) - The NCWF, designed and 

implemented by NCAR, provides current convective hazards and 1-hour extrapolation forecasts 

of thunderstorm hazard locations. The hazard field and forecasts update every 5 minutes. The 

NCWF development is sponsored by the FAA AWR program as part of the Convective Weather 

PDT. The Convective Weather PDT consists of MIT Lincoln Laboratories, National Severe 

Storms Laboratory (NSSL), National Weather Service's Aviation Weather Center (AWC), and 

NCAR. This graphic can be accessed via the ADDS web site under “Convection” 

(http://adds.aviationweather.noaa.gov/convection/java).

1/19/06 AC 120-88A 

 Appendix 4 

 Page 1 (and 2) 

APPENDIX 4. DELIVERY: NEW AND EMERGING TECHNOLOGIES, 

PRODUCTS AND SERVICES TO DELIVER TURBULENCE 

INFORMATION 

(1) Flight Deck Uplink. Flight deck uplink of graphic weather products uses 

Uplink product standards and the associated flight deck display systems. Carry-on display 

systems such as the Electronic Flight Bag (EFB) are being developed as a first generation flight 

deck weather display system. Second generation systems (new aircraft production) will feature 

flight deck panel mounted displays, designed to be compatible with the uplink graphics 

developed for the carry-on systems such as the EFB. Flight deck weather uplink is supported by 

several NASA/FAA/industry system/program initiatives, and associated standard setting 

activities.

• AWIN: Aviation Weather Information is a broad based Government/industry 

initiative to provide advanced weather products into the flight deck 

http://awin.larc.nasa.gov/overview.htm

• WINNCOMM: Weather Information Network COMMunication – NASA 

program that is investigating communication alternatives of weather products to 

the flight deck. This program will support flight deck initiatives such as AWIN 

http://wxap.grc.nasa.gov/wincomm/

• EWXR: Enhanced Weather Radar is a program to develop advanced processes 

for utilization of on-board weather radar information. Features under 

development include storm motion tracking, weather hazard analysis, storm top 

determination, and combination of airborne and ground based weather products to 

create a composite strategic and tactical weather display 

(2) Flight Deck Uplink Standard Setting Activities 

• RTCA Special Committee SC-195: This committee is developing the standards 

for data link of graphical weather to the flight deck 

(3) Aircraft Sensor Systems. Aircraft weather radar enhancements and new 

aircraft turbulence sensors are being developed under several government/industry programs: 

• EDR: Eddy Dissipation Rate is a derived atmospheric parameter for defining 

atmospheric turbulence developed by NCAR as part of the FAA Turbulence PDT. 

EDR software utilizes inputs from standard aircraft performance systems to generate 

an aircraft independent turbulence metric. ICAO has adopted EDR as the 

international standard for automated turbulence reporting. Currently, one airline has 

100 aircraft downlinking average and peak EDR values at one-minute intervals 
1/19/06 AC 120-88A 

 Appendix 5 

 Page 1 

APPENDIX 5. GRAPHICAL DEPICTION OF SOME OF THE DATA 

 USED IN THIS ADVISORY CIRCULAR

The following pages contain data compiled from NTSB accident reports relating to turbulence over the 

period 1980-2003. 

Plots show year-to-year numbers and trend lines for: 

• Turbulence Accidents, 1980 – 2003, U.S. Air Carriers 

• Turbulence Accidents Per Million Departures, U.S. Air Carriers, 1982 - 2003 
0

369

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80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 

APPENDIX 5. GRAPHICAL DEPICTION OF SOME OF THE DATA USED 

IN THIS ADVISORY CIRCULAR (Continued)

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AC 120-88A 1/19/06 

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1/19/06 AC 120-88A 

 Appendix 5 

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