## National Transportation SafetyBoard 

# /
WashingtonD.C. 20594 

### Safety Recommendation

Date: August 15, 1996



### In reply referto: A-96-48 through 

### -69

HonorableDavid R. Hinson Administrator FederalAviation 

### Adminisbation Washington, D.C. 20591

On October 

### 31, 1994, at 1559 Central Standard Time, 

### an Avions de Transport Regional, model 72-212 (ATR 72), registrationnumber N401AM, leased to and operated by 

### Simmons Airlines, Incorporated, and doing 

### -business-as-(d,b~a~)-~encan-Eaglefligh184~crash~d-d~g a rapiddescent after 

### an uncommanded roll excursion. The airplane was 

### in 

### a holding pattern and was descending to 

### a newly assigned altitude of 8,000 feet when the initial roll excursion occurred. The airplane was destroyed by impact forces; and the captain, ftrst officer, 2 flight attendants and 64 passengers received fatalinjuries. Flight4184 was a regularly scheduledpassenger flight being conducted under 14Code of FederalRegulations 

### (CFR) Part 121; and



### aninsmentflightrules flightplan hadbeen filed.'

'For more detailed information, read Aircraft Accident Report--"In-flight Icing Encounter and Loss of Control, Simmons Airlines, d.b.a. American Eagle Right 4184, Avions de Transport Regional (ATR), Model 72-212, N401AM, Roselawn, Indiana, October31, 1994" (NTSB/AAR-96/01)

6486C2

I The National Transportation Safety Board has determined that the probable causes of this accident were the loss of control, attributed to a sudden and unexpected aileron hinge moment reversal that occurred after a ridge of ice accreted beyond the deice boots because: 1) ATR failed to completely disclose to operators, and incorporate in the 

### ATR 72 airplane flight manual, flightcrew operating manual and flightcrew training programs, adequate information concerning previously known effects of freezing precipitation 

### on the stability and controlcharacteristics, autopilot and related operationalprocedures when the ATR 72was operated in suchconditions; 2) the French Directorate General for Civil Aviation's (DGAC's) inadequate oversight of the ATR 42 and 72, and its failure to take the necessary corrective actionto ensure continued airworthiness

### in icing conditions; and 

### 3) 

### the DGAC's failure to provide the Federal Aviation Administration (FAA) with timely airworthiness information developed from previous ATR incidents and accidents in icing conditions, as specified under the Bilateral Airworthiness Agreement and Annex 

### 8 of the International Civil Aviation Organization.

Contributingto the accident were: 1)the FAA's failure 

### to 

### ensure that aircraft icing certification requirements, operational requhments for flight hito icing conditions, and FAA published aircraft icing information, adequately accounted for the hazards that can result from flight in freezing rain and other icing conditions not specified in 14CFR Part 25, Appendix C; and 2) the FAA's inadequate oversight of the ATR 42 and 72 to ensure continuedairworthinessin icing conditions.

As a result of the investigation of this accident, the Safety Board 

### has concluded that the weather forecasts produced by the National Weather Service (NWS) were correctbased 

### on the available information, and that the actions of the forecasters at 

### the National Aviation Weather Advisory Unit, Kansas City, and the Center Weather Service Unit meteorologists at the Chicago air route traffic control center were in accordance with NWS guidelines and procedures.

Nonetheless, the Safety Board 

### has some concerns about the lack of weather information disseminated

### to the crew offlight4184. 

### Specifically,the information contained in 

### AIRh4E'Ts [airman's meteorological information] 

### "Zulu,""Sierra" and "Tango," andUpdate 2, was availablewell 

### in advance of3

flight 4184‘s departure, and was pertinent to the airplane‘s route of flight. This informationwas not, and typically would not be, included in the weather portion of the flight release provided by Simmons Airlies/AMR Eagle. Further, it could not be determined if the flightcrew had obtained the updated weather information via the hazardous in-flight weather advisory service (HIWAS)while enroute orprior to the recorded conversations on the cockpit voice recorder 

### (CVR).

14 CFR 

### Part 121.601 (b) and (c) state, 

### in part, respectively, “before beginning-aflight

### the-aircraft-dispatcher-shall-provide-thcpilot-in-commandwith all available weather reports and forecasts of weather phenomena that may affect the safety of flight” and that during a flight the dispatcher shall provide 

### “any additional available information of meteorological conditions including adverse weather phenomena.“ FAA Order 8400.10, paragraph 1423, (Operational Requirements 

## - Flightcrews) requires that AIRMET informationbe considered 

### in the preflight planning process; however, Center Weather Advisories (CWAs) 

### are not required to be included or considered. 

### SimmonsAirlines dispatchersreview the AIRMETs,but they do not typically include them in the flight release package. CWAs 

### are not included in the release packages because they are not required. The Safety Board is concerned that because 

### Simmons Airlines dispatchers do not include AIRMETs (which include information regarding moderate icing) and CWA information, flightcrews may not be provided “all available weather reports and forecasts

### of

### weatheiphenornenahecssaqtomakeinformed decisions.

Althoughthe Safety Board concludesthat the actions of the flightcrew would not have been significantly different if they had received the AIRMETs, the Safety Board believes that 

### Simmons AirlinedAMR Eagle should require its dispatchers to include in the flight release AIRMETs and CWAs that 

### are pertinent to the route of flight 

### so that 

### this information can be available for preflight and in-flight decisionmaking. Therefore, the Safety Board believes that the FAA should direct its principal operations inspectors 

### (POIs) to ensure that all air carriers 

### require their dispatchers to provide pertinent information, including AIRMETs 

### and CWAs, 

### to flightcrews for preflight and in-flight planning purposes. Further, the FAA should Revise FAA Order 8400.10, Chapter 

### 7, Section 

### 2, paragraph 1423 to specify that CWAs be included and considered 

### in the flightcrew’s preflight planning process.4

With regard to the availability of in-flight weather information, the Safety Board notes that the HIWAS broadcast generated by the Kankakee (AFSS) included all of the icing information contained in AIRMET "Zulu," Update 

### 3. Although the 

### HIWAS broadcast generated by the Terre Haute AFSS indicated that icing was forecast above the freezing level, it did not indicate the icing levels, the intensity and type of icing, or the existence of icing conditions in clouds and precipitation included in AKRMET "Zulu," Update 

### 3. The Safety Board understands that the HIWAS broadcasts are intended to provide hazardous weather information in a short format that will facilitate the pilot's understanding of the potentially hazardous conditions. However, 

### the Safety Board concludes that safety would be enhanced if the information were presentedmore consistently among HIWAS stations and if those broadcasts included all of the information pertinent to the safety of flight, such as the altitudes of the icing conditions, the intensity and type of icing, and the locationofthe actualorexpected icing conditions (i.e. in clouds and precipitation). Therefore, the Safety Board believesthat the FAA should require that 

### HIWAS broadcasts consistently include all pertinent information contained in weather reports and forecasts, including in-flight weather advisories (AIRMETs, SIGME'I's, and CWAs). The Safety Board also believes that the FAA and 

### air carriers should reemphasize to pilots that 

### HIWAS 

### is 

### a source of 

### timely weather information and that it should be used whenever aircraft 

### are operating in or near areas of potentially hazardous weatherconditions.

Air traffic controllers 

### are required by FAA Order 

### 7110.65 to solicit a pilot report (PREP)when certainweather conditions that are specified in the order 

### are either forecast or reported for the area of jurisdiction. "Lighter or greater

# ..."icing conditions, which include freezing rain, are one of the five conditions specified

### by the order 

### for which a controllerwill solicit a PREP. When the BOONE sector controller assumed control of the position and received a briefing by the departing controller, he was told, 

### "...no one was complaining about the weather." This included flight 

### 4184 which had been

on the radio frequency for approximately 

### 3 minutes when the BOONE controller assumed control. Because there were 

### no PREPSprovided to the previous controller, and the crew 

### of flight 

### 4184 did not provide a PIREP of icing conditions 

### at the 

### LUCI" intersection, it was reasonable for the controllerto assumethat there were

### no significantweather events in that area, and 

### that 

### the 

### crew of flight 

### 4184 

### was not experiencing 

### any problems that

### 5

would have required the controller to take alternative actions. Nonetheless, the Safety Board believes that the FAA should revise FAA Order 7110.65, “Air Traffic Control,” Chapter 2, “General Control,” Section 6, “Weather Information,” paragraph 2-6-3, “PIREP” Information, to include freezing drizzle and freezingrain. These conditions should also be clearly defined 

### in thePiloVControllerGlossary.

The investigation revealed that although the icing definitions in the Aeronautical InformationManual 

### (AIM) provide some basis for assessing ice accumulation%-PIREPs; they-are-subjectiv-daf lifEt~Wt~il~6T different aircraft types. For example,using these definitions, “light”icing for

a B-727 could be “severe”icingfor an ATR 72or 

### a Piper Malibu. The icing report provided by the captain of the A-320 Airbus that was holding at the 

### HALEintersectionnearRoselawn indicated that he observed about 1inch 

### of ice accumulate rapidly on his aircraft‘s icing probe. The captain provided a PIREP to 

### air traffic control (ATC) and reported the icing as “light rime.” After the accident, he stated that the anti-ice equipment 

### on the airplane “handled the icing adequately,”and that he believed the icing intensity tohave been “light tomoderate.”

The Safety Board concludes that icing reports based on the current icing severity definitions may often be misleading to pilots, especially to pilots 

### of aircraftthat may be more vulnerable to the effectsoficing conditions 

### -than-others7-Therefore~the-Safe~Board-believes~t-~e-F~-s~o~ld

develop new aircraft icing intensity reporting criteria that are not subjective andarerelated to specifictypesof aircraft.



### In addition, the investigation revealed 

### a problem with the aviation carnmunity’s general understanding of the phrase “icing in precipitation,” which is used by the NWSbut is not definedin any aeronautical publications, including advisory circulars, Part 1

### ofthe Federal AviationRegulations or the 

### AIM. 

### This phrase 

### is often contained

### in in-flight weather advisories; however, it does not typically specify types 

### of precipitation. According to the 

### NWS, this

### phrase is intendedto include freezing

### drizzle and freezing rain. Therefore, the Safety Board concludes that defining “icing in precipitation” 

### in these publications would make pilots and dispatchers more aware of the types 

### of precipitation and icing conditions that 

### are implied by this phrase. Accordingly, the Safety Board believes that the FAA should provide a6

definition of the phrase "icing in pmcipitation"in the appropriate aeronautical I publications. Fwther, the SafetyBoard believes the FAA should require all POIs of 14CFR Part 121 and 135 operators to ensure that training programs include information about all icing conditions, including flight into freezing drizzle/freezingrain.

Based 

### on the evidence uncovered in 

### this accident, the Safety Board believesthat the cmnt methods offorecastingicing conditions are of limited value because they typically cover very large geographic areas, do not provide specific informationaboutliquid water content (LWC) or water drop sizes, and use only relative humidity and temperature. According 

### to testimony from a scientist from the National Center for Atmospheric Research (NCAR), it 

### is not possible 

### to infer the severity 

### of icing using only temperature and humidity. Rather, the severity of the icing also depends 

### on the LWC and the size of the water droplets, information which 

### is not currentlyidentifiedandforecasted.

The Safety Board is concerned that there are 

### no reliable methods for flightcrews to differentiate, in flight, between water 

### drop sizes that 

### are outside the 14CFR 

### Part 25, Appendix C, icing envelope and those within the envelope. Further, although side window icing was recognized as 

### an indicatorof ice accretionsfromfreezing drizzle during fight tests of 

### an ATR 72 after the accident, the crew offight 4184could not have been expected

### to know this visual cue because its significance was unknown to the ATR pilot communityatthe time. Moreover, in-serviceA?'R incidents and pilot reports have shown that side window icing does not always accompany ice accretions aft of the deice boots, which ATR has stated only occurs 

### in freezing drizzleand/or freezing rain.

The Safety Board acknowledges the efforts of atmospheric research in the meteorological cornmunity and hopes that its importarit findings will eventually provide the aviation industry with a better understanding of the freezing drizzlehain phenomenon. "he Safety Board concludes that the continueddevelopmentof atmospheric measuring and monitoring equipment, such as atmospheric profilers, use of the WSR-88D [weather surveillance radar] and teiminal Doppler weather radars, multispectral satellite 

### data, aircraft-transmitted atmosphericreports,and sophisticatedmesoscale models, and the development

### of computeralgorithms, such 

### as those contained in the I7

FAA's Advanced Weather Products Generator program to provide comprehensive aviation weather warnings, could permit forecasters to refine the data sufficiently to produce more accurate icing forecasts and real-time wamings. Therefore,the SafetyBoard believes thatthe 

### FAA should continue
to 

### sponsor the development of methods to produce weather forecasts that define very specific locations of potentially hazardous atmospheric icing conditions(including freezingdrizzle and freezing rain) and to produce shortrange forecasts ("nowcasts") that identify icing conditions for 

### a specific geographic area with avalid time of 2hoursorless. __.-_l______-._-.l..--------.--.--.-. - Although the SafetyBoard has foundno evidence that the ATR 42 and 72 were not properly certificated for flight into icing conditions, the investigation 

### has raised a number of concerns relating to the process for certlfying 

### an airplane for flight into icing conditions. Among these concerns


### are the acceptance by regulatory authorities of a limited number of icing test data points, most of which 

### are not 

### near the boundaries of the envelope; the limited range of conditions 

### (LWC and MVD [median volumetric diameter] size) provided by the Appendix C icing certification envelope; the lack of standardized methods for processing LWC and MVD data; the implied authorization of flight into conditions beyond the envelope; and the certification of stallprotection systems that 

### are intended to prevent exposure to undesirable (even dangerous) characteristics of the airplane without 

### a requirement for the manufacturer 

### to advise the 

### FAA, operators, and pilots of

.- -such-sharasteristics.

This investigation has revealed that the ATR 42 and 72 were not required to be tested throughout a significant portion of the icing conditions that 

### are specified in the Appendix C icing envelope. The limited number of
test points accepted by the 

### FAA as sufficiently comprehensive were well within the boundaries of 

### the envelope and did not include the warmer, near freezing conditions at the 

### upper boundary 

### of the Appendix C envelope in which run-back icing and asymmetric slidingkhedding are likely to occur. 

### Thus, by allowing liited 

### data well within the envelope to suffice 

### for certification purposes, the 

### FAA effectively precluded 

### any chance of identlfying the phenomena that led to flight 4184's ice ridge buildup, uncommandedailerondeflection andlossofcontrol.

### 8

The SafetyBoard's concern about the adequacyof Appendix C criteria ( was heightenedby the results of one December 1994ATR icing tankertest 

### in which ice accumulatedbehind the active portion of the ATR 

### 72's deice boots during exposure to water droplet sizes of only 57 microns MVD, which is only slightly outside the Appendix C envelope. Further, 

### data developed by NACA, the NASA predecessor, indicated in the 1950s that MVDs of 70 microns ormore could be encountered in layer clouds. Flight 

### in layerclouds is not 

### anunusualeventinthis country,butflight into layercloudscanresult in encounters with icing conditionsbeyond those set forth in 

### 14 CFR Part 25, Appendix C. Several ATR 42 icing incidents with ice 

### aft of the boots occurredin layer clouds, which supports the conclusion that icing encounters in high altitude layer clouds can exceedthe capabilitiesof aircraftcertified to the Appendix

### C envelope.

Thus, because the Appendix Cenvelope is limited and does not include larger water drop conditions, such as freezing drizzle or freezing rain (conditionsthat can be routinely encountered in winter operations throughout much of the northern United States, and were most liely encountered by flight 4184), 

### the Safety Board concludes that the current process by which aircraft 

### are certified using the Appendix C icing envelope is inadequate and does not require manufacturers to sufficiently demonstrate the 

### airplane's capabilitiesundera sufficiently realisticrange 

### of icing conditions.



### In addition,the lack of standardized methods forprocessing icing data
to determine MVDs raises concern that certification icing tests may be conducted at actual MVDs below the calculated values. For example, during the series of icing tanker tests atEdwards

### Air Force Base, it was determined that 

### two generally acceptedmethods ofcalculating MVD and LWC provided sigrdcantly different results. Therefore, it 

### is possible that airplanes certificated 

### in accordance with Appendix C criteria may not actually have been tested in the icing conditions described 

### in the certification documentation. Thus, the Safety Board believes that the FAA should revise the icing certification requirements and advisory material to speclfy the numerical methods to be used 

### in determining 

### MVD and LWC during certificationtests.

I A sigdicant Safety 

### Board finding in 

### this investigation is that 

### no airplane 

### shouldbe authorized

### orcertified forflightinto icing conditionsmore9

severe 

### thanthose to which the airplane was subjected in certificationtesting, unless the manufachwr can otherwise demonstratethe safetyofflight 

### in such conditions. Although

### no aircraftare certified forflight intofreezing drizzle or freezing rain, the ATR 72 flight manual did not spec@ the operational limits and capabilities of the airplane 

### in conditions such as freezing drizzle and freezing rain.

Currently,FAA ground deice and anti-ice programs permit operators to dispatch aircraft into freezing drizzle and light freezing rain2 provided they use-TypeX anti=ice-fluid-and-respect-the-speGified-holdover-timetables~-- - --- Specifically, Flight Standards Information Bulletin (FSIB) for Air Transport @SAT), 95-29, dated October 25, 1995, statesthat Type

### TI deicing fluid will be used when "operating during light freezing rain and freezing drizzle weather conditions" and that the "use of special procedures (Le. visual inspections, remote deice capability) is required." The Safety Board recognizes that the 

### FAA's intent ofthis 

### FSAT 

### is to provide operators with the



### means to dispatch airplanes that will quickly depart and climb through the freezing drizzle or light freezing rain conditions and that the 

### FAA's permission of limited operations 

### in fitezing drizzle and light freezing rain is apparently based on the assumption that the airplane will depart within the prescribed "holdover" time of the anti-ice fluid, and transit 

### through the freezing drizzle/light freezing rain conditions with minimal exposure. However,

### FSAT95-29 does not specificallystate that continuedflightin such condi t

### ionsis-prohbited.The-Safe~-Board-is-concemed-that-in-some situations it may be necessary to operate in such conditions for 

### an extended period of time. One such situation 

### is the failure of 

### an engine shortly after takeoff, a situationthat could requiremaneuveringfor

### an indeterminate period oftime while returning to 

### the departure airportwhere freezing drizzle or light freezingrain conditionsareknown

### toexist.

FtuTher, although it 

### is known by 

### many in the aviation 

### community that flight into freezing drizzle 

### or freezing rain is not safe, the Safety Board 

### is

unaware of 

### an explicit provision 

### in the Federal Aviation Regulations that

TheNCAR definitionfor light freezingrain is: "measuredintensity up to 0.10 inh (2.5 mm or 25 g/drn*/hr);Maximum 0.01 inch in 6 minutes from scattered drops that, regardlessof duration, donot completely wet an exposed surfaceup to a condition where individualdropsareeasily seen."10

prohibits flight into freezing drizzle and freezing 

### rain. Additionally, as was noted in the Safety Boards 1981study on aircrafticing, airplanes certificated for flight into known icing are authorized 

### to fly into weather conditions that produce "severe" icing under 14CFR Parts 91, 135 and 121. However, by definition, severe icing conditions result in a rate of ice accumulation that exceeds the capabilitiesof the airplane deice/anti-icingsystem or that require immediatediversionfrom theplanned route offlight.

The Safety Board is concerned that these unclear and inconsistent messages to pilots aboutthe operation of aircraftthat 

### are certified forflight in icing conditions may create the misconception that flight 

### in freezing drizzle and/or freezing rain is acceptable when it is not. Such confusing and apparently contradictory information could have contributed to the belief by Simmons AirlinedAMR Eagle management that it was permissible for ATR 42 and 72 airplanes 

### to be dispatched and flown into conditions of freezing drizzle and light freezing rain when it disseminated a memorandum 

### to its pilots 

### in 1991settingforththe conditionsfor suchflights.

The Safety Board concludes that no airplane should be authorized or certified for flight into icing conditions 

### more severe than those 

### to which the airplane was subjected in certification testing unless the manufacturer can otherwise demonstrate the safety of flight in such conditions. 

### Thus, the Safety Board believes that the FAA should revise its certification regulations
to ensure that airplanes are properly tested for all conditions in which they are authorized 

### to operate, or are otherwise shownto be capable 

### of safe flight 

### into such conditions. 

### If safe operation cannot be demonstrated by 

### the manufacturer, operational limitations should be imposed 

### to prohibit flight in such conditions, and flightcrews should be provided with the 

### means to positively determine when they 

### are in icing conditions that exceed the 

### limits foraircraftcertification.

The SafetyBoard understandsthat as a resultofthis accident, the FAA 

### is currently planning a review of its icing certification and operational regulations, including the icing severity definitions issue. The Safety Board supports and encourages 

### this action but believes that the FAA should revise 14 

### CFR 

### Parts 91.527 and 135.227 in a tirrKly manner to ensure that the regulations 

### are compatible with the published definition of severe icing, and11

to eliminate the implied authorization of flight into severe icing conditions for aircraft certifiedforflightin suchconditions.

The Safety Board recognizes that the risk of another 

### ATR 42 

### or 72 accident resulting from 

### an uncommanded aileron excursion in freezing drizzlelfreezing rain 

### has been reduced by 

### the addition of extended deice boots, improved operational procedures, extensive crew training, and heightened awareness by pilots. Because wind tunnel and in-flight tanker
tests have been performed for only a limited range of icing and flight

- _--conditions,-the- Safety- Board-remains 

### concemed-whetheri-even-with- the improvements, the airplane can be controlled under all naturally occurring combinations of conditions of liquid drop size and content, temperature, airplane configuration,load factors, speeds,and time ofexposure. Moreover, the Safety Board found that ATR’s post-Roselawn brochure entitled, 

### “ATR Icing Conditions Procedures,” 

### still does not adequately address or clearly represent the exact nature of the ATR ice-induced aileron hinge moment reversal.

The Safety Board notes that Special Condition B6, developed by the MjAC in the 1980’s and initially applied during the 

### ATR 72 certification, includes a ”zero

### G” flight test maneuver (pushover) designed to identlfy iceinduced elevatorhinge moment reversals. The SafetyBoard understands that at least 

### some manufacturers in the world aviation community (including the UntehStates)-are-cancemed-that-Special-~ondition-B6-is-too-de~ding~ particularly the tailplane icing pushover test. However, the Safety Board concludes that the addition of a test procedure to determine the susceptibility to aileronhinge moment reversals in both the clean and iced-wing conditions could help 

### to prevent accidents such as that involving flight 4184. Thus, the Safety Boardbelieves thatthe 

### FAA should develop a test procedure similar to the tailplane icing pushover test to determine

### the susceptibility of airplanes to aileron hingemoment reversals inthe clean and iced-wing conditions.

As part of the investigation, the Safety Board reviewed historical accident and incident 

### data of 

### similarturbopropeller aircraft. The

### data did not show other airplane models to have a 

### similar incidenvaccident history involving uncommanded aileron excursions in the presence of freezing drizzle/freezingrain. One possiblereason forthis is that othermodel aircraft



### use hydraulically powered ailerons, smaller mechanical ailerons with larger

### 12

hydraulically powered spoilers, or different balancehinge moment control j devices toprovide adequateroll control with less propensity for aileronhinge
moment reversals. The Safety Board understands that ATR 

### is considering design changes to the lateral control system for current and future ATR airplanes that 

### are expected to reduce the susceptibility to flow separationinduced aileron hinge moment reversals and/or uncommanded aileron deflections. The Safety Board concludes that such design changes, if effective, would reduce the need to 

### rely on 

### the changes to flight operations and pilot training that have alxeady been mandated 

### to ensure the safety of flight. 

### Thus, the SafetyBoard believes that 

### the FAA should encourage ATR
to test lateral control 

### system design changes and, if they correct the aileron hinge moment reversal/uncommanded aileron deflection problem, require these design changes on allexisting andnew ATR airplanes.



### In a related area, the SafetyBoard is concerned that the FAA and other airworthiness authorities still permit airplane manufacturers to use stall protection systems (SPS) 

### to prevent flightcrews from experiencing known undesirable flight characteristics unique to their particular aircraft design without requiring the manufacturers to reveal these characteristics to the airworthiness authorities,operators, andpilots. According to ATR, its use of



### an SPS to prevent, among otherthings, aileronhinge moment reversals in the clean and iced configurations was not explained to the ainvorthiriess authorities or the operators because ATR was not required to do 

### so. The Safety Board concludes that the failure ofthe DGAC and the FAA to require that they be provided with documentation of known undesirable post-SPS flight characteristics contributed to their failure to identlfy and correct, or otherwiseproperly address, the abnormalaileron behavior early 

### in the history 

### of the ATR icing incidents. Therefore, the Safety Board believes that the 

### FAA should 

### require aircraft manufacturers to provide, 

### as part of 

### the certification criteria, information 

### to the 

### FAA and operators about 

### any known undesirable flight characteristics beyond the SPS and related shaker/pushier flightregime.

Evidence 

### from 

### the investigation revealed that the 

### FAA's Aircraft Evaluation Group (AEG) does not maintain a data base of incidenvaccident information. Moreover, a communications deficiency resulted in the failure ofthe AEG 

### to receivepertinent documentationregarding ATR icing incidents that could 

### have been used 

### to monitor the continued airworthiness of the I

### 13

airplane. This is not the first time that the Safety Board has identifed problems with the timeliness and effectiveness 

### of the 

### FAA's continuing airworthinessoversightofforeign-built aircraft. The SafetyBoard noted 

### in its 1987 report on the crash 

### of a CASA C-212-CC that the 

### FAA's monitoring 

### of airworthinessissues relating 

### to that aircraftwas inadequate. Specifically,that investigation revealed that the FAA delayed for more 

### than 3 years taking actions to correct known issues 

### of noncompliance with 14CFR Part 25, and that there "was 

### an apparent lack 

### of standardization and coordination" among various officeswithin theFAA.3

_____-l_lll~.__._I-...___ _II-. Accordingly, the Safety Board concludes that the lack of defined lines of communication and adequate means to retrieve pertinent airworthiness information prevented the AEG from effectively monitoring the continuing airworthinessof aircraft. Therefore, 

### the Safety Board believes that the FAA should develop 

### an organizational structure and communications system that will enabletheAEG to obtain and record all domesticand foreign aircraft and partshystems manufacturers' reports and analyses canceming incidents and accidents involving aircraft types operated in the LJnited States, and ensure that the information 

### is collected 

### in a timely manner for the effective 

### AEG monitoring 

### ofthe continued airworthinessof aircraft.

The investigation 

### has revealed the 

### FAA's limited involvement during 

### the initial certification of the ATR 42 and 72. 

### For example, there were s-exeralmee

### tingsin_wbch-only-one-pemon-from-thcEAA-~viewed-vas t amounts of certification documentation and had to resolve prablems from 

### many technical disciplines. Further, because FAA personnel were either unavailable, or budget constraints restricted travel, issues involving noncompliance or other concerns were resolved 

### through "issue papers." 

### An issue paper, 

### ofwhich there were 

### more 

### than90 forthe ATR 42 and 17for the ATR 72, describes 

### the FAA's position on a certification 

### issue and the method@) necessary to achieve compliance. For the ATR, the 

### FAA delegatedthe compliance oversightforthe issue papers

### to the DGAC.



## - - 3NTSBAccidentReportAAR-88-08,FischerBros.Aviation,Inc., dba Northwest Airlink,Flight2268,Construcciones Aeronauticas,S.A, (CASA) C-212-CC.Detroit Metropolitan Wayne County Airport, Romulus, Michigan, March 4, 1987,p.44.14

Included in the certification process is the FAA review of test data, including data acquired

### fromflight tests. Accordingto testimonyprovidedby the FAA's ATR certification team leader, the FAA does not flight test the aircrak rather, it conducts "evaluation" flightsfor the purpose of "familiarity with airplane



## ...and [to]determine suitabilityforuse in airline service

## ...." The FAA conducted about 10 hours of evaluation flights 

### on the ATR; however,

none of these flights duplicated any tests required for certification, and none



### were conductedin icing conditions.



### The Safety Board concludes that 

### the FAA's limited involvement 

### in the AIR 42 certification 

### does not appear to have resulted 

### in an improperly certificated airplane (ATR 42/72). However, such excessive reliance on a foreign airworthiness authority could result 

### in improper certification of an aircraft. Therefore, the Safety Board believes that the FAA should review and revise, as necessary, the manner 

### in which it monitors a foreign airworthiness authority's compliance with U.S. type certification requirements underthe Bilateral Airworthiness Agreement (BAA).

The Safety Board is also concerned about the process by which the FAA ensures the continuing airworthiness of airplanes certificated under the BAA. For example, the FAA did 

### not receive pertinent information about the airworthiness of the ATR 42 and 72 series airplanes, including AIR'S analyses of the icinginduced aileron hinge moment reversal incidents in 1991, and those in 1993 and 1994. The FAA could have been more aggressive in requesting data from the DGAC following these incidents. However, the DGAC should have, on its own accord, taken actions to de

sure that the FAA was provided with all information about the ATR incidents 

### to ensureFAA involvement

### in the continuing airworthiness ofthe airplane.

The Safety Board concludes 

### that the 

### FAA's ability to monitor the continued airworthiness of the ATR airplanes has 

### been hampered 

### by 

### an insufficientflow ofcritical airworthiness information. The DGAC's apparent belief that such information was not required to be provided under the terms 

### of the BAA raises 

### concerns about 

### the scope and effectiveness 

### of the BAA. Thus, the Safety Board believes that the FAA should establish policies and procedures to ensure that all 

### pertinent information is received, including the manufacturer's analysis of incidents, accidents or other airworthiness issues,15

fromthe exporting country’sairworthiness authority 

### so that it can monitor and

ensurethe continuedairworthinessof airplanes certified underthe BAA.



### In this accident, the flightcrew did not indicate that it was concerned about holding in icing conditions,but the Safety Board notes that there were


### some potentially distracting events durlng the hold. The cockpit voice recorder 

### (CVR)recordedabout 

### 15minutes of

### personal conversationbetween a flight attendant and the captain from 1528:Qo 

### to 1542:38. The CVR also recorded music playing for about 18 minutes, as well as the sounds of the

___ ____I---- captain’s departure-from-thecockpit-for-aboutSminutes-to use-the-restroom;-
According to 14 CFR 

### Part 121.542 (the “sterile cockpit” mle) and FAA staff testimony at the Safety Boards public hearing on this accident, holding at 10,000feet or above is not considered to be 

### a “critical” phase of flight. 

### Thus, the presence of the flight attendant in the cockpit and the ensuing conversation were not in violation of 

### AMR Eagle policy or Federal regulations.

Althoughthe presence of the flight attendant and the music could have been a distraction to the flightcrew, both pilots appeared attentive to flightrelated duties immediately before, as well as duringthe roll upset. Thus, the Safety Board concludes that neither the flight attendant’s presence in the cockpit nor the flightcrew’s conversations 

### with her contributed 

### to the _accident .Be-Safety-Board-no ted,-ho wever,tha 

### t-the-AMR-Eagle-A-TR-7-2 flightmanual gives the captain the authority to declare 

### “any other phase of a particular flight“ a critical phase depending on the circumstances and thus to invoke the sterile cockpitrule. Therefore, the Safety Board concludesthat a sterile cockpit environment would have reduced flightcrew distractions and could haveheightenedthe flightcrew’sawarenessto the potentiallyhazardous environmental conditions in which the airplane was being operated. However, the sterile cockpit environment would not have increased the flightcrew’s understanding of the events that eventually transpired. Nonetheless, the SafetyBoardbelievesthat the 

### FAA should evaluate the need
to 

### require a sterile cockpit environmentfor 

### all air carriers holding in 

### certain weatherconditions, suchas icing and convective activity.



### Inthis accident, the Safety Board attempted to determinewhy the crew offlight4184 was unable to successfully recover the airplane and prevent the16

accident when 

### the flightcrews of the airplanes involved in the prior incidents 

### i

were able to do 

### so. At the time ofthe accident, the AMR Eagle pilot training program did not include 

### an "unusual attitude" or "advanced maneuvers" segment (nor was such training required). During simulator training, 

### AMR Eagle pilots were not exposed to aircraft attitudes that were typically beyond those used for 

### normal operations or considered unusual, and they only experienced 

### an abnormal pitch attitude when they practiced emergency descents.

In four separate safety recomnendations over the past 27 years, the Safety Board

### has addressedthe issue 

### ofunusual attitudetraining. The 

### FAA's unfavorable responses and failureto require such training have resulted in the Safety Board classifyingthe FAA'spast actions as "Unacceptable"

### inthree of the four cases. In the fourth case, Safety Reconmendation A-93-72, the FAA's actions to promulgate rules to bring most 14CFR 

### Part 135 scheduled passenger operators under 14

### CFR 121training requirements (which include the use of simulaton)was classified "Closed-Acceptable Action" 

### on August 29, 1995. However, the Safety Board remains concerned that this does not necessitatea requirement to provide unusual event/attitude training.

Based 

### on the circumstances of this accident, the historical data of similar accidents, and safety recommendations previously issued by the SafetyBoard, the FAA, in August 1995,

### injoint cooperationwith the aviation industry, issued 

### an FAA Inspector Handbook Bulletin detailing a program that encourages

### air carriers to implement advanced maneuver/unusual attitude training in theirpilot training program. AMR Eagle implemented 

### an unusual attitude training curriculum into its pilot training syllabus, action that the Safety Board supports. Additionally, the Safety Board is encouraged by the FAA's latest position regarding 

### unusual attitude/events training; however, there remains a concern that the kick of a required program might result in



### some carriers not providingunusual attitude training, and that theirrespective training programs might be insufficient to demonstratethe cause for and the recovery from aircraft attitudes that 

### are not considered to be "~iormal." Therefore,the Safety Board believes that the 

### FAA should amend the Federal Aviation Regulations to require 

### air carriers 

### to provide standardized training that adequately addresses the recovery 

### from unusual events and attitudes, includingextreme flightattitudes, in large, transportcategoy airplanes.17

Therefore, as a result of its investigation of this accident, the National Transportation Safety Board recommends that the Federal Aviation Administration:

Direct principal operations inspectors (Pols) to ensure that all 14 Code 

### of Federal Regulations (CR) Part 121 air carriers require their dispatchers to provide all pertinent information, including airman’s meteorological infomation (AIRMETs) and CenterWeather Advisories (CWAs), to flightcrewsforpreflight and in-flightplanning

.. purgoses.

.. (Class --.--?-.-- 

### II Priority Action) 

### {A:- 96-48) ~~.-I

Require that Hazardous In-flight Weather Advisory Service (HIWAS) broadcasts consistently include all pertinent informationcontainedin weather reports and forecasts, including in-flight weather advisories, airman’s meteorological information (AIRMETs), significantmeteorologicalinformation (SIGMETs), and Center Weather Advisories (CWA’s). (Class 

### II, Priority Action) (A-96-49)

Encourage principal operations inspectors 

### (Pols)and operators to reemphasize to pilots that Hazardous In-flight Weather Advisory Service (IIIWAS) is a source of timely weather information and should be used whenever they are operating in

or near areas 

### of potentially hazardous weather conditions. (ClassTI, Priority Action) (A-96-SO)

Revise the existing aircraft icing intensity reporting criteria (as definedinthe AeronauticalInformation Manual 

### (AIM) and other Federal Aviation Administration (FAA) literature) 

### by including nomenclaturethat

### is related to specific

### types of aircraft, and that 

### is in logical agreement with existing Federal Aviation Regulations (FARs). (Class 

### 11,Priority Action) (A-96-51)

Publish the definition ofthe phrase “icinginprecipitation”in the appropriate aeronautical publications, emphasizing that the condition

### may exist both near the ground and at altitude. (Class 11,PriorityAction) (A-96-52)18

Continue to sponsor the development of methods to produce weather forecasts that both define specific locations of atmospheric icing conditions (including freezing drizzle and freezing rain) and produce short-range forecasts (“nowcasts”) that identlfy icing conditionsfor a specific geographic area with a valid time of2hours or less. (Class I[,Priority Action) (A-96- 

### 53)

Revise the icing criteria published in 14 Code of Federal Regulations 

### (CFR),Parts 

### 23 and 

### 25, in light of both recent research into aircraft ice accretion under varying conditions of liquid water content, drop size distribution,and temperature, and
recent developments inboththe design and use of aircraft. Also, expand the Appendix C icing certification envelope to include freezing drizzle/freezing rain and mixed water/ice crystal conditions, as necessary. (Class 

### II,P~iority Action) ) (A-96-54) (Supersedes A-81-116 and -118)

Revise the Federal Aviation Regulations (FARs) icing certification requirements and advisory material to spec@ the numericalmethods to be used in determining median volunietric diameter 

### (MVD)and liquid water content (LWC) during certification tests. (Class 

### 11,PriorityAction) (A-96-55)

Revise the icing certification testing regulation to emure that airplanes are properly tested for all conditions 

### in which they are authorized to operate, or 

### are otherwise shown to be capable of safe flight into such conditions. 

### If safe operations 

### carmot be demonstratedby the manufacturer, operationallimitations should 

### be irnposed to prohibit flight in such conditions and flightcrews shouldbe provided with the 

### meam to positively determine when they are in icing conditions that exceed the liits for aircraft certification. (Class

### II,PriorityAction) (A-96-56)

Require all aircraft manufacturers to provide, as part of the certification criteria, information 

### to the 

### FAAand operators about 

### any known undesirable characteristics of flight beyond the19

protected (stall system and related shaker/pusher) flight regime. (Class z[, PriorityAction) (A-96-57)

Develop 

### an icing certification test procedure similar to the tailplane icing pushover test to determine the susceptibility 

### of airplanes to aileron hinge moment reversals in the clean and iced-wing conditions. Revise 14 CFR Parts 23 and 25 icing certification requirements to include such a test. (Class 11, Priority Action) (A-96-58)

Encourage ATR 

### to test the newly developed lateral control system designchanges and upon verification 

### of the improved or corrected hinge moment reversal/uncommanded aileron deflectionproblem, require these design changes 

### on all new and existingATR airplanes. (Class-11,Priority Action) (A-96-59) ___-- _.____l.l_l____l_l_.---.l-l----.---..--- -.I..-.__-____

Revise 14 CFR Parts 91.527 and 135.227 to ensure that the regulations 

### are compatible with the published definition 

### of

severe icing, and to eliminate the implied authorization 

### of flight into severeicing conditions for aircraft certified forflight in such conditions. (Class

### II,PriorityAction) (A-96-60)

Require all principal operations inspectors 

### (POIS) of 14CFR 

### -Part-l-2l1-and-l-3-5-operators-to-ensm-that-tra~g-programs include information about all icing conditions, including flight into freezing drizzle/freezing rain conditions. (Class 

### 11, Priority Action) (A-96-61)

Develop 

### an organizational structure and a communications system that will enable the Aircraft Evaluation Group (AEG)to obtain and record all domestic and foreign aircraft and parts/systems manufacturers’ 

### reports and analyses concerning incidents and accidents involving aircraft types operated 

### in the United States, and ensm that the information 

### is collected 

### in a timely manner for effective

### AEG monitoring of the continued airworthinessof 

### aircraft. (Class

### TI, Priority Action) (A-96-62)

### 20

Review and revise, as necessary, the manner in which the FAA monitors a foreign airworthiness authority’s compliance with U.S. 

### type certification requirements under the Bilateral AirworthinessAgreement (BAA). (Class 

### II, Priority Action) (A96-63)

Establish policies and procedures to ensure that all pertinent information

### is received, including the manufacturer’s analysis of incidents, accidents or other airworthiness issues, 

### from the exportingcountry’s airworthiness authority 

### so that the FAA can monitor and ensure the continued airworthiness of airplanes certified under the Bilateral Airworthiness Agreement (BAA). (Class 11,Priority Action) (A-96-64)

Evaluate the need to require a sterile cockpit environment for airplanes holding in such weather conditions as icing and convective activity, regardless of altitude. (Class 

### 11, Priority Action) (A-96-65)

Amend the FederalAviation Regulations to require operators to provide standardized training that adequately addresses the recovery from unusual events, including extreme flight attitudes in large, transport category airplanes. (Class 

### II, Priority Action) (A-96-66)

Revise 

### FAA Order 8400.10, Chapter 7, Section 

### 2, paragraph 1423 (Operational Requirements 

### - Flightcrews) 

### to specify that Center Weather Advisories (CWAs)be included and considered in the flightcrew’spreflight planning process. (Class 

### II, Priority Action) (A-96-67)

Revise 

### FAA Order 7110.65, “Air Traffic Control,” Chapter 

### 2, “GeneralControl,” Section6,“Weather Information,” paragraph 2-6-3, “PIREP” Information, 

### to include freezing drizzle and freezing 

### rain. Additionally, these conditions should be clearly defined in 

### the PilotlController 

### Glossary. (Class 

### II, Priority Action) (A-96-68)21

Conduct or sponsor research and development 

### of on-board aircraft ice protection and detection systemsthat will detect and alert flightcrews when the airplane 

### is encountering freezing drizzle and freezing 

### rain and accreting resultant ice. 

### (Class 

### II, PriorityAction) (A-96-69)



### Also,the Safety Board issued Safety Recommendations A-96-70 to the National Oceanic and Atmospheric Admhstration and A-96-71 through -73
to AbfR Eagle.

________________.---.-I Chairman

### HAL,L, and Members HAMMERSCHMIDT, 

### GOGLIA, and BLACK concurred in these recommendations. Vice Chairman

### FRANCIS did 

### not participate.



## [, Ch& L.. 

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