U.S. Department 

of Transportation 

Federal Aviation 

Administration 

DRAFT 

Advisory 

Circular 

Subject: Guidance for Conducting and Use of 

Flight Standardization Board Evaluations. 

Date: Draft for 

comment 

Initiated by: AFS-200 

AC No: 120-53B 

Change: 

1. PURPOSE. The FAA is seeking comment on this draft advisory circular (AC) which 

provides information and guidance on the supplemental notice of proposed rulemaking, 

Qualification, Service, and Use of Crewmembers and Aircraft Dispatchers, which was published 

for comment on May 20, 2011. This advisory circular (AC) describes an acceptable means, but 

not the only means, of compliance with the Title 14 of the Code of Federal Regulations 

regarding training, qualification, and type rating of flight crewmembers operating under CFR 

Part 121. Included are criteria for the determination and approval of training, checking, and 

currency necessary for the operation of aircraft. Details of the systems, processes, and tests 

necessary to apply this AC are explained in the appendices. This AC is intended to enhance 

safety by: 

• Providing a common method of assessing applicant programs 

• Directly relating pilot training and qualification requirements to fleet characteristics, 

operating concepts, and pilot assignments 

• Permitting better planning and management of fleets, pilot assignments, and training 

resources by outlining what FAA requirements apply, what training resources or devices 

are needed, and what alternatives are possible 

• Permitting timely and consistent decisions about fleet acquisition, integration, 

modification, or phaseout associated with pilot training, qualification, or pilot 

assignments 

• Permitting manufacturers to design aircraft that take advantage of new technology or 

their similarity with existing related aircraft, as appropriate to a particular operator’s fleet 

• Encouraging cockpit standardization by crediting commonality and identifying necessary 

constraints when differences exist 

• Providing a recommended framework for application of suitable credits or constraints to 

better address new technology and future safety enhancements 
AC 120-53B DRAFT MM/DD/YY 

Page 2 Par 4 

Comments to this draft AC may be submitted to the docket for the corresponding rulemaking, 

docket FAA 2008-0677 at www.regulations.gov before the comment period for the rulemaking 

closes. 

2. CANCELLATION. AC 120-53A, Guidance for Conducting and Use of Flight 

Standardization Board Evaluations, dated OCT 15, 2008, would be cancelled upon review of the 

comments to this draft AC and publication of the final rule and guidance material for this 

rulemaking. 

3. FOCUS. This AC addresses aircraft manufacturers or modifiers who design, test, and 

certificate aircraft. In addition, it reflects those changes in 14 CFR Part 121 which apply to 

operators whose pilots operate related aircraft of the same manufacturer in a mixed fleet and 

operators seeking credit for prior pilot experience with related aircraft of the same manufacturer. 

4. DISCUSSION. 

A System for Pilot Training and Qualification. The FAA specifies qualification criteria 

(minimum training, checking, and currency) for particular aircraft through Flight Standardization 

Board (FSB) evaluations and findings. FSB findings are described in reports for specific aircraft. 

The reports provide guidance to certificate-holding district offices (CHDO) for use by principal 

operations inspectors (POI) and other inspectors. FSB reports may serve as a basis for the FAA 

to approve operators’ programs and for pilot certification. 

When requested by industry, the Flight Standards Service (AFS) of the Federal Aviation 

Administration (FAA), through the Aircraft Evaluation Groups (AEG) will undertake an analysis 

of new and derivative aircraft and their associated systems for the purpose of providing 

recommendations for training, checking, recency of experience and operating experience, as well 

as pilot certification. The FAA uses these analyses to develop consistent and practical 

recommendations for the training, checking, currency, recent experience and certification of 

pilots for transport aircraft. These recommendations are documented in FSB reports for each 

aircraft, and may be used by a certificate holder to develop its training programs. FSB findings 

are described in reports for specific aircraft or related aircraft. The FSB report establishes 

provisions for training program modification for related aircraft for flightcrew members. The 

reports provide guidance to certificate-holding district offices (CHDO) for use by principal 

operations inspectors (POI) and other inspectors. FSB report recommendations serve as a basis 

for the FAA to approve operators’ programs under CFR §121.1206 “Designation of Related 

Aircraft”, CFR §121.1215 “Modification of Training Programs”, and CFR §121.1230 “Deviation 

from the requirements of §121.1225 “Flight Crewmember Operating experience”, §121.1227 

“Consolidation”, and §121.1229 “Recent experience.”

a. Changing Needs. Necessary support for the FSB process is provided by the industry. In 

the past, procedures varied by manufacturer, individual project, operator, and other factors 

including: 
MM/DD/YY DRAFT AC 120-53B 

 

Par 5 Page 3 

(1) Introduction of new and related aircraft and increases in the significance of 

modifications to existing aircraft, particularly with regard to engines or avionics. 

(2) Integration of related fleets of aircraft following airline acquisitions or mergers. 

(3) Increased dependence on leased aircraft, many of which are configured differently 

than an operator’s basic fleet. 

(4) A wider variety of equipment options available in new or retrofit aircraft. 

 (5) Introduction of new technology in cockpit enhancements. 

5. SUMMARY OF REVISIONS. This AC describes necessary revisions and enhancements to 

the FSB process to address uniform, systematic, timely, and comprehensive application of 14 

CFR Part 121 in a changing and increasingly complex operational environment. This AC 

recognizes the concept of reduced differences between related aircraft and defines the training, 

checking, currency, and recency of experience requirements. 

a. This AC revision clarifies, and introduces new terms and concepts. These include: 

(1) Clarification of the terms “aircraft type certificate” and “related aircraft”. 

(2) The difference between currency and recency of experience is defined. 

(3) A new definition of “common type rating” which defines a specific relationship 

between a type rating specific to a given type certificated aircraft with another type rating 

specific to a separate type certificated aircraft of the same make. This new definition conforms to 

the current provisions of CFR Part 121. The applicability of this definition is based on the levels 

of difference between the aircraft. 

(4) Modified checking requirements to embrace the concept of checking only at the 

difference levels between related aircraft. 

(5) A new term, “common takeoff and landing credit” (CTLC). 

(6) An introduction of the T6 test to provide for CTLC (recency of experience) in mixed 

fleet flying between separate type-certificated aircraft of the same make with common takeoff 

and landing characteristics. The intent of the T6 test is to provide a comparison of aircraft that 

have not previously been evaluated for CTLC using the T2 test. 

(7) A means to identify and evaluate new technologies that may not be associated with an 

aircraft evaluation. 

(8) A distinction between supervised line flying (SLF) and operating experience (OE). 

6. SETTING FAA REQUIREMENTS. The FSB process is made up of proposal 

development, testing, draft provisions formulation, FSB final determinations and FAA approval. 
Page 4 Par 6 

a. Applicant’s Proposals. Aircraft manufacturers or modifiers usually initiate proposals for 

formulation or amendment of FSB provisions. This is done in conjunction with application for 

aircraft type certification or supplemental type certification of an aircraft or system. The FAA, 

operators, and, in certain instances, other organizations or individuals, may initiate proposals or 

amendments. 

b. Standardized Tests. A main element of the requirements formulation process is the use 

of standardized testing to determine pilot training and qualification requirements. One or more of 

six tests are applied depending on the proposal’s degree of differences between related aircraft, 

difference levels sought, and the outcome of any previous tests. Only the necessary tests are 

used. Tests may be waived or difference levels may be assigned based on operational experience. 

c. FAA Formulation and Implementation of FSB Provisions. Following testing and 

formulation of draft provisions, FSB determinations are then made specifying Master Difference 

Requirements (MDR) and any necessary supporting information. Supporting information may 

pertain to operator certification, airmen certification, and other items necessary for proper 

application of MDRs. FSB reports will be used in the evaluation, certification, and approval of 

operators’ programs. 

d. Revision of FSB Provisions. FSB reports are periodically updated when new or 

modified aircraft are introduced, when requested by an applicant based on OE, or when the FAA 

determines it is necessary for safety reasons. 

e. Type Ratings. A new type rating is typically assigned when an aircraft is built under a 

new type certificate. A new type rating may also be assigned if level E training differences are 

determined between a candidate aircraft and the base aircraft. The type rating determination and 

any training, checking, and currency specifications established under the testing process of this 

AC are determined by evaluating the handling qualities and core pilot skills related to the 

candidate aircraft. 

7. OPERATOR COMPLIANCE WITH FAA REQUIREMENTS.

a. Obtaining FSB Information. Operators are advised of pertinent FSB information 

through FAA CHDOs and POIs. Operators may also obtain FSB information from aircraft 

manufacturers or modifiers, other operators, or other aviation organizations that maintain 

awareness of FAA policies, and the Web site http://www.opspecs.com. 

b. Certificated Operator Compliance with Mixed Fleet Flying. When aircraft are flown 

in mixed fleets, certificated operators will comply with the applicable 14 CFR Part 121 

requirements and the associated QPS. Certificated operators operating related aircraft who have 

received approval for modifications to flightcrew training and qualification as provided by 

121.1215 will comply with Operator Difference Requirements (ODR) as approved by their 

Certificate Management Office (CMO) or Certificate Holding District Office (CHDO) and 

concurred by the Air Transportation Division, AFS-200. For operation of related aircraft in 

mixed fleets the certificated operators identify a base aircraft, describing differences that exist 

between their base aircraft and the candidate aircraft, and by specifying particular means of 

compliance to satisfy MDRs. Sample FSB ODRs provide guidance for the approval of an 
Par 8 Page 5 

operator’s mixed fleet flying program and specify necessary constraints or permissible credits. 

The description of specific differences and compliance methods are identified in the operator’s 

ODRs. Constraints or credits may relate to knowledge, skills, Flight Simulator Training Devices 

(FSTDs), maneuvers, checks, currency, or any other factors necessary for safe operations. 

Constraints or credits may be applied generally or only to specific aircraft or pilot positions. 

Once approved, the operator’s program will be conducted in accordance with (IAW) these 

approved ODRs. ODR proposals are provided to the FAA CHDO in a standard tabular format 

and are approved by POIs only if they meet MDRs and other pertinent FSB provisons. The 

operator may apply to amend the ODRs when changes occur in the base aircraft, comparison 

aircraft, and/or FSTDs that affect the approval basis of the ODRs. 

8. APPLICATION OF FSB PROVISIONS TO AIRMEN CERTIFICATION. The 

evaluation items that FSB reports specify include the following: 

• Knowledge 

• Skills 

• Abilities 

• Maneuvers 

• Performance criteria 

• Other relevant items for proficiency checking 

9. FSTD APPROVALS. 

a. FSTDs are associated with each of the training difference levels. FSTDs are approved for 

particular operators by their POIs IAW CFR Part 60 and 121.1345. In some instances, standard 

FSTD criteria may not be appropriate for new technology. The FSB may specify additional 

criteria in FSB reports in these instances. 

10. REVIEW AND APPROVAL. This is a process for review of FSB evaluations and approval 

of FSB reports. 

11. APPEAL OF FAA DECISIONS. The Director, Flight Standards Service, AFS-1, assigns 

responsibility to resolve appeals of the FSB findings 

John Allen 

Director, Flight Standards Service 

MM/DD/YY DRAFT AC 120-53B 

 Appendix 1 

Page 1 

APPENDIX 1. DEFINITIONS AND REFERENCES 

TABLE OF CONTENTS 

1. DEFINITIONS...........................................................................................................................2 

2. REFERENCES (current editions)..............................................................................................5 
AC 120-53B DRAFT MM/DD/YY 

Appendix 1 

Page 2 

APPENDIX 1. DEFINITIONS AND REFERENCES 

1. DEFINITIONS. 

NOTE: Definitions provided in Appendix 1 apply exclusively to this advisory 

circular (AC). 

a. Aircraft Evaluation Group (AEG). FAA organization that sets training, checking, 

currency, type rating, Master Minimum Equipment List (MMEL), and maintenance standards 

for assigned certificated aircraft types. AEGs also address operational aspects of aircraft type 

certification and resolution of service difficulties. 

b. Applicant. For the purposes of this AC, an applicant may be a manufacturer, modifier, or 

operator. 

c. Base Aircraft. An aircraft designated by the applicant and used as a reference to 

compare differences with another aircraft. 

d. Candidate Aircraft. The aircraft that will be subjected to the FSB evaluation process 

outlined in this AC for comparison purposes. 

e. Check. An assessment of crewmember proficiency during which limited training or 

practice is allowed. The assessment is of knowledge and skill in tasks to the standards identified 

and required by the appropriate QPS. If the check is given for the purpose of flight crew member 

certification it will be considered a test. That test is an assessment of crewmember proficiency 

during which additional training or practice is not allowed. 

f. Common Type Rating. “Common type rating” is a term used in FSB reports to describe 

a relationship between type ratings for aircraft with different type certificates that are defined in 

14 CFR Part 121 as “related” having no greater than a level D training differences. The type 

rating for a certificated aircraft can be determined to be related to another type rating of another 

certificated aircraft of the same make provided the aircraft meet the criteria of the T1 

(equivalence) or the T2 (handling characteristics) and T3 (core pilot skills with no greater than 

level D differences). The pilot who is receiving a type rating on the basis of being related must 

be current and qualified in the base aircraft at the time of the check and is issued a type rating 

after receiving differences training and checking on the candidate related aircraft. This check is 

not a “full” proficiency check, but an abbreviated check on the differences from the base to the 

candidate aircraft. The differences check, unless it includes the requirements for a recurrent 

check, cannot reset the “recurrent clock” (a pilot’s base month for checking purposes). 

g. Common Takeoff and Landing Credit (CTLC). CTLC is a program/process that 

allows recency of experience credit between related aircraft (same make) with the same or 

different type certificate data sheets (TCDS) that can be demonstrated to have the same handling 

and flying characteristics during the following: 

• Takeoff and initial climb 
MM/DD/YY DRAFT AC 120-53B 

 Appendix 1 

Page 3 

• Approach and landing, including the establishment of final landing configuration 

NOTE: The T6 test is used for aircraft that were not tested (T2) during the 

initial aircraft evaluation for type rating designation. 

h. Configuration. Aircraft physical features, which are distinguishable by pilots, with 

respect to differences in systems, cockpit geometry, visual cutoff angles, controls, displays, 

aircraft geometry, and/or number of required pilots. 

i. Currency. Currency is the recent experience necessary for the safe operation of aircraft, 

equipment, and systems as designated by the Flight Standardization Board (FSB). 

j. Difference Levels. Difference levels are formally designated levels of training methods 

or devices, checking methods, or currency methods that satisfy differences requirements between 

related aircraft. A range of five difference levels in order of increasing requirements, identified 

as A through E, are specified for training, checking, and currency purposes. 

k. Differences Training. Training required before any person may serve as a required 

crewmember on an aircraft of a type for which differences training is included in the certificate 

holder’s approved training program. 

l. Differences Check. A partial proficiency check of the qualification of a pilot at the 

difference levels between related aircraft. A differences check can be between series of aircraft 

on the same aircraft type certificate (TC) or between aircraft of separate aircraft TCs of the same 

manufacturer and is based on the certificate holder’s approved training and qualification 

program. 

m. Flight Characteristics. Flight characteristics are handling characteristics or performance 

characteristics perceivable by a pilot. Flight characteristics relate to the natural aerodynamic 

response of an aircraft, particularly as affected by changes in configuration and/or flight path 

parameters (e.g., flight control use, flap extension/retraction, airspeed change, etc.). 

n. Flight Operations Evaluation Board (FOEB). The FOEB is responsible for preparation 

and revision of Master Minimum Equipment Lists (MMELs). The board members are drawn 

from the FAA. 

p. Flight Simulator Training Device (FSTD). A Full Flight Simulator (FFS) or a Flight 

Training Device (FTD). 

q. Flight Standardization Board (FSB). The FSB is responsible for specification of 

minimum training, checking, currency, and type rating requirements, if necessary, for U.S. 

certificated civil aircraft. The board members are drawn from the FAA (AEG, Headquarters, 

Flight Standards field offices operations personnel). 

r. Handling Characteristics. The manner in which the aircraft responds with respect to 

rate and magnitude of pilot initiated control inputs to the primary flight control surfaces (e.g., 

ailerons, elevator, rudder, spoilers, cyclic, collective, etc.). 

Page 3 (and 6) 

s. Line Oriented Flying (LOF). The LOF phase of the test is used at the discretion of the 

FSB during the T3 test to validate the proposed training and checking. The LOF fully assesses 

particular difference areas, examines implications of mixed fleet flying, assesses special 

circumstances such as minimum equipment list (MEL) effects, and evaluates the effects of pilot 

errors potentially associated with the differences. 

t. Master Difference Requirements (MDR). MDRs are those requirements applicable to 

pilot training and qualifications that pertain to differences between related aircraft. MDRs are 

specified by the FSB in terms of the minimum difference levels. MDRs form the basis for an 

operator to develop their operator differences requirements (ODR). 

u. Mixed Fleet Flying. Mixed fleet flying is the operation of a base aircraft and one or more 

related aircraft for which credit may be taken for training and/or checking events. The FSB 

process defines minimum training, checking, and currency difference levels between related 

aircraft. 

v. Operational Characteristics. As used with respect to aircraft, means those features that 

are distinguishable by limitations, flight characteristics, normal procedures, nonnormal 

procedures, alternate or supplementary procedures, or maneuvers. 

w. Operator Difference Requirements (ODR). If differences exist within an operator’s 

fleet that affect pilot knowledge, skills, or abilities pertinent to systems or procedures, ODR 

tables provide a uniform means for operators to comprehensively manage difference programs 

and provide a basis for FAA approval of mixed fleet flying. 

x. Recency of Experience. With respect to flight experience as required by 14 CFR 

121.1229, means a pilot’s completion of the required number of takeoffs and landings as sole 

manipulator of the controls within a specified period of time. 

y. Related Aircraft. Any two or more aircraft of the same make with either the same or 

different type certification data sheets that have been demonstrated and determined to have 

commonality to the extent that credit between those aircraft may be applied for training, 

checking, recency of experience, or operating experience, as authorized by the FAA. 

z. Same Type Rating. A type rating is assigned when no greater than a level D training 

difference is determined between a series of aircraft with the same aircraft TCs. 

aa. Series. Aircraft sharing the same aircraft Type Certification (TC). Specific variations that 

are usually defined by the manufacturer and usually result in an amended aircraft TC. 

bb. Supplementary Procedures. Those procedures that are identified in the Flight Crew 

Operation Manual (FCOM) under the section “Supplementary Procedures” describing 

procedures not described under the “Normal Procedures” or “Nonnormal Procedures” sections. 
Page 4 

cc. Supervised Line Flying (SLF). Supervised experience associated with the introduction 

of equipment or procedures requiring post qualification skill enhancement during which a pilot 

occupies a specific pilot position and performs particular assigned duties for that pilot position 

under the supervision of a qualified company instructor or check airman. 

dd. Training Footprint. A training footprint is a summary description of a training program, 

usually in short tabular form, showing training subjects, modules, procedures, maneuvers or 

other program elements, which are planned for completion during each day or phase of training. 

ee. Type Rating. A type rating is a “one time”, permanent endorsement on a pilot certificate 

indicating that the holder of the certificate has completed the appropriate training and 

qualification as required by 14 CFR 121.1333. It is recorded by the FAA on the pilot’s certificate 

indicating the make, model, and series of aircraft, if applicable. 

2. REFERENCES (current editions). 

• Title 14 CFR Part 121 

• Title 14 CFR Part 60 

• Order 8900.1, Flight Standards Information Management System 

• AC 61-89, Pilot Certificates, Aircraft Type Ratings

• AC 120-35, Line Operational Simulations: Line Oriented Flight Training, Special 

Purpose Operational Training, Line Operational Evaluation 

• AC 120-40, Airplane Simulator Qualification 

• AC 120-45, Airplane Flight Training Device Qualification 

• AC 120-51, Crew Resource Management Training 

• FAA-S-8081-5, Aircraft Type Rating Practical Test Standards for Airplane 
MM/DD/YY DRAFT AC 120-53B 

 Appendix 2 

Page 1 

APPENDIX 2. PILOT TRAINING, QUALIFICATION, AND PILOT RATING 

REQUIREMENTS 

TABLE OF CONTENTS 

1. PURPOSE............................................................................................................................4 

2. FOCUS................................................................................................................................4 

3. INTRODUCTION 

a. A Comprehensive System for Pilot Training and Qualification................................. 4 

b. Master Differences Requirements (MDR) Set by FAA.............................................. 4 

c. Specification of Constraints or Credits....................................................................... 4 

d. Recognition of Unique Operator Characteristics........................................................ 4 

e. Basis for Requirements............................................................................................... 5 

f. Relationship to other FAA Policies. ........................................................................... 5 

4. CONCEPTS 

a. An Integrated System for Pilot Training and Qualification........................................ 5 

b. MDRs.......................................................................................................................... 5 

c. Difference Levels........................................................................................................ 8 

d. Training Difference Levels......................................................................................... 9 

e. Checking Difference Levels ..................................................................................... 11 

f. Currency Difference Levels...................................................................................... 12 

g. Operating Experience (OE) for Aircraft ................................................................... 15 

h. Supervised Line Flying (SLF) .................................................................................. 15 

i. Recency of Experience. ............................................................................................ 16 

j. Operator Difference Requirements (ODR)............................................................... 16 

5. FORMULATION OF FSB REPORTS, MDRs, AND DESIGNATION OF TYPE RATINGS. 

a. Requirements Formulation Process Overview.............................................................. 24 

b. Proposals for MDRs, Example ODRs, and Special Requirements ................................ 24 

c. Difference Level Tests. ............................................................................................... 27 

d. FSB Assessments and Proposal Formulation. .............................................................. 27 

e. Comments Solicited.................................................................................................. 31 

f. FSB Final Determinations and Findings................................................................... 31 

g. FSB Report Preparation Distribution and FAA Application. ................................... 32 

h. FSB Report Revision. ............................................................................................... 33 

6. OPERATOR’S APPLICATION OF FSB PROVISIONS, PREPARATION, USE, AND 

REVISION OF ODRs. 

a. General...................................................................................................................... 34 

b. Application of MDRs and Preparation and Use of ODRs. ....................................... 34 

c. Selecting Base Aircraft. ............................................................................................ 35 

d. Identification of Differences and the Analysis of Effects of Those Differences...... 35 

e. Identification of Compliance Methods. .................................................................... 36 

f. When Proposed ODR Compliance Methods Do Not Meet MDRs........................... 36 
AC 120-53B DRAFT MM/DD/YY 

Appendix 2 

Page 2 

g. Application, Review and Approval........................................................................... 36 

h. Implementation Provisions Transition Period. ......................................................... 37 

i. ODR Revision........................................................................................................... 37 

7. FAA REVIEW AND APPROVAL OF OPERATOR PROGRAMS 

a. General...................................................................................................................... 40 

b. Operator Application of ODRs. ................................................................................ 40 

c. Base and Other Aircraft Identification...................................................................... 41 

d. Approval of ODRs. ................................................................................................... 42 

e. FSB Revision of MDRs or Other FSB Provisions.................................................... 42 

f. Proving Tests. ........................................................................................................... 43 

g. Line-Oriented Flight Training (LOFT) or SLF......................................................... 43 

h. OE ............................................................................................................................. 43 

i. Limitations on the Total Number of Related Aircraft .............................................. 43

j. Compliance Checklist for CHDOs............................................................................ 43 

k. Aircraft That Do Not Have an FSB Report .............................................................. 44 

8. APPLICATION OF REQUIREMENTS TO AIRMEN CERTIFICATION. 

a. General...................................................................................................................... 44 

b. Checks Regarding Complex Systems. ...................................................................... 44 

9. FSTD APPROVAL.................................................................................44 

a. NSP Representation to the FSB.............................................................44 

10. REVIEW AND APPROVAL... .........................................................................................44 

11. APPEAL OF FAA DECISIONS .......................................................................................45 

ILLUSTRATIONS 

Figure 1. Master Difference Requirements (MDR) Table Example..........................................7 

Figure 2. Difference Level Table .............................................................................................15 

Figure 3-1. Design Operator Differences Requirements Table Example....................................18 

Figure 3-2. Systems Operator Differences Requirements Table Example..................................19 

Figure 3-3. Maneuver Operator Difference Requirements Table Example ................................23 

Figure 4. Master Requirements Formulation ...........................................................................28 

Figure 5. Test Definitions.........................................................................................................29 

Figure 6. “T” Tests 1 Thru 5 ....................................................................................................30 

Figure 7. Standard Method and FSTDs....................................................................................32 
MM/DD/YY DRAFT AC 120-53B 

 Appendix 2 

Page 3 

Figure 8. FSB Process ..............................................................................................................39 

APPENDIX 2. PILOT TRAINING, QUALIFICATION, AND PILOT RATING 

REQUIREMENTS 
AC 120-53B DRAFT MM/DD/YY 

Appendix 2 

Page 4 

1. PURPOSE. This appendix describes a comprehensive system for pilot Training and 

qualifications outlined in this advisory circular (AC). It includes definitions, criteria, processes, 

tests, methods, and procedures necessary for uniform application of the system. 

2. FOCUS. The appendix applies to and is used by: 

• Aircraft manufacturers or modifiers who design, test, and certificate under Title 14 of the 

Code of Federal Regulations. 

• Operator, manufacturer, or other training centers having programs approved for use under 

14 CFR Part 121. 

• Federal Aviation Administration (FAA) offices and inspectors administering programs 

under 14 CFR Part 121. 

3. INTRODUCTION. 

a. A Comprehensive System for Pilot Training and Qualification. This AC and its 

appendices provide a systematic means to address requirements for training, checking, and 

currency within applicable 14 CFR Part 121. Definitions, criteria, processes, procedures, tests, 

and methods are consistent with and clarify application of current rules in particular situations 

for specific aircraft. This AC describes a comprehensive system for the FAA and industry to 

evaluate and approve use of particular aircraft and operator programs. The respective roles of 

training, checking, and currency are clarified. This includes defining the role and criteria for 

designation of type ratings for existing, new, or modified aircraft. The system is particularly 

suited to addressing transition, differences programs, and mixed fleet flying. The system aids in 

assuring that pilots attain and maintain the knowledge, skills, and abilities needed to operate 

assigned aircraft safely. 

b. Master Differences Requirements (MDR) Set by FAA. The FAA’s Flight 

Standardization Board (FSB) sets MDRs to address differences between related aircraft. 

c. Specification of Constraints or Credits. The system permits the specification of 

constraints or permissible credits. Constraints or credits may relate to knowledge, skills, abilities,

FSTDs, maneuvers, checks, currency, or any other such factors necessary for safe operations. 

Constraints or credits may apply generally to aircraft, particular pilot positions, or other 

situations or conditions. 

d. Recognition of Unique Operator Characteristics. The system recognizes the unique 

characteristics of individual operators while achieving uniformity in application of FAA safety 

standards. FAA MDRs determine uniform bounds to tailor individual operator’s unique 

requirements to a particular fleet and situation. Principal operations inspectors (POI) approve 

each operator’s unique requirements within FAA MDRs. Operator unique requirements 

accommodate particular combinations of related aircraft flown, pilot assignment policies, 

training methods and devices, and other factors that relate to the application of the FAA MDRs. 

Accordingly, the system preserves operator flexibility while standardizing the FAA’s role in 
MM/DD/YY DRAFT AC 120-53B 

 Appendix 2 

Page 5 

review, approval, and monitoring of training, checking, currency, and mixed fleet flying 

programs as applicable to14 CFR Part 121. 

e. Basis for Requirements. The determination of type rating, minimum differences 

training, checking and currency requirements focus on basic operation of aircraft in the National 

Airspace System (NAS) under both instrument flight rules (IFR) and visual flight rules (VFR). 

Included are all flight phases from preflight to shutdown under both normal and nonnormal 

conditions. 

f. Relationship to other FAA Policies. Although this AC, and the FSB provisions in some 

instances, address particular types of operations or specific aircraft systems (e.g., use of flight 

guidance control systems for Category II/III instrument approaches, long-range navigation, etc.), 

other ACs address these issues more thoroughly. This AC and FSB provisions address such 

issues only to the extent necessary to assure that pilots are qualified to operate pertinent systems 

or equipment as part of initial or continuing qualification. 

4. CONCEPTS. 

a. An Integrated System for Pilot Training and Qualification. 

(1) System Elements. An integrated FAA/applicant system and process established to 

determine appropriate requirements, applies the requirements, and meets those requirements on a 

continuing basis, for uniform pilot Training and qualification. 

(2) System Overview. The system uniformly applies FAA master requirements in a way 

that tailors a particular aircraft, to any operator’s unique situation or fleet. The FAA approves 

unique operator and fleet requirements for each operator based on FAA master requirements. 

The system develops FAA master requirements based on objective criteria and tests, with 

applicants’ support for analysis, and testing. FSB reports for related aircraft describe FAA master 

requirements. MDRs express FAA master requirements (the minimum acceptable difference 

levels between related aircraft). An operator’s training program, checklist, operations manuals, 

pilot certification, CTLC programs, and other such approvals are by-products of compliance with 

MDRs. Operators comply with MDRs using unique ODRs, tailored to that operator’s programs 

and approved by the FAA. ODRs, based on and in compliance with the MDRs, specify 

requirements uniquely applicable to a particular operator’s mixed fleet flying situation. An 

operator’s specific document describes ODRs by identifying a base aircraft, differences between 

related aircraft, and that operator’s compliance methods for each related aircraft. Paragraph 4j 

describes ODRs. Paragraph 6 describes ODR preparation and use. Paragraph 7 describes FAA 

approval of ODRs. 

b. MDRs. 

(1) MDR Applicability. MDRs are those requirements applicable to pilot training and 

qualification that pertain to differences between related aircraft. MDRs specify the minimum 

acceptable difference levels between related aircraft that may be approved for operators. One 

related aircraft is selected by the applicant as a reference for comparison purposes and is 

considered a base aircraft. This is typically the first aircraft on which pilots are qualified, or is 

the aircraft of which an operator has the largest number. Difference levels between the base 
AC 120-53B DRAFT MM/DD/YY 

Appendix 2 

Page 6 

aircraft and other related aircraft then specify the minimum difference requirements to be met for 

pilot training and qualification. Major differences in a particular fleet are defined between groups 

of related aircraft rather than specifying differences between each possible configuration and 

combination of configurations between related aircraft. MDRs are specified in terms of training, 

checking, and currency difference levels described in paragraph 4d and are shown on an MDR 

table. 

(2) MDR Content. MDRs specify the minimum training, checking, and currency 

acceptable to the FAA for pilot training and qualification regarding differences. 

(3) MDR Formulation, Description, and Revision. MDRs are formulated by the FAA 

FSB for each related aircraft. MDRs are originally specified when an aircraft is first type 

certificated. MDRs are formulated using standardized tests and evaluations in conjunction with 

the type certification or supplemental type certification process. MDRs are based on an 

applicant’s (usually an aircraft manufacturer) proposal, FAA evaluation of that proposal, OE, 

and test results when tests are necessary. FSB determinations also consider operator 

recommendations, safety history, and other relevant information. MDRs are described in 

provisions of an FSB report and may be revised if necessary. MDRs are revised when aircraft are 

developed or modified, tests or OE shows a need for revision, a revision is requested by an 

applicant and evidence indicates the need for revision, or rules or FAA policies change. MDRs 

are revised by a process similar to that used for initial formulation of requirements. 

(4) MDR Use. MDRs are applied to specific operators through formally described 

ODRs that are developed by and tailored to each operator. FAA field offices use the MDRs as 

the basis for approval of individual operator’s differences programs for approval of initial or 

transition programs where credit for previous training or experience with other related aircraft is 

sought. 

(5) The MDR Table. An example of typical MDRs for the B-737-200, 300, 400, 500, 

600, 700, 800, and 900 is shown in Figure 1. MDR table requirements are shown for each pair of 

aircraft by notations in each element of corresponding columns and rows of the table. Each 

element of the table identifies the minimum differences training, checking, and currency 

requirements applicable to mixed fleet flying. The MDR table identifies a pertinent base aircraft 

and particular aircraft for which requirements are sought. Note the minimum difference levels 

that correspond to the pertinent column and row, and special requirements in footnotes, if 

applicable. 

(6) Use of Higher or Lower Difference Levels. Operators will satisfy difference 

requirements by using the methods acceptable for the specified level or a higher level. Lower 

level methods may be used in addition to the required levels but may not substitute for the 

required level or be used exclusively instead of the required level. 
Page 7 

FIGURE 1. MASTER DIFFERENCE REQUIREMENTS (MDR) TABLE 

(7) Differences within a Series. Differences may exist even within series shown on an 

MDR table, such as within the A-318/319/320/321 series. MDR elements may show 

requirements from one series to another identified in the footnotes. Such requirements however, 

apply only if pertinent differences exist between those aircraft. 

(8) More than One Related Aircraft. When an operator assigns a pilot to more than 

one related aircraft of the same type certificate (ie B -737-100/200/300/400/500/next generation), 

or more than one related aircraft of different type certificates (ie A-320, A-330, and A-340), each 

pertinent requirement of the MDR table applies. 

(9) Special Requirements. 

(a) MDR Footnotes. Footnotes can be used to credit, constrain, or set alternate levels 

when special situations apply. Use of footnotes permits accommodation of variations in installed 

equipment, options, pilot knowledge or experience on other aircraft, training methods or devices, 

or other factors that are not addressed by basic levels between aircraft. For example, a footnote 

FROM AIRCRAFT 

TYPE RATING: 

B-737 B-737 BASIC 

B-737-100, 200 

(SP77) 

B-737-200 

ADV 

B-737-300, 

400, 500 

(NON-EFIS) 

B-737-300, 

400, 500 

(EFIS) 

B-737-600, 

700, 800, 900 

B-737 BASIC 

B-737-100, 200 

(SP77) 

A/A/A 

(2) NAV-B/B/C 

(6) PMS-C/B/C 

B/A/B 

(2) NAV-B/B/C 

(6) PMS-C/B/C 

C*/C*/D C*/C*/D D/D/D 

B-737-200 ADV B/A/B 

(1) PDCS- 

 C/B/C 

(2) NAV-B/B/C 

(4) AFCS- 

 C/B/C 

(6) PMS-C/B/C 

A/A/A 

(1) PDCS- 

 C/B/C 

(2) NAV-B/B/C 

(4) AFCS- 

 C/B/C 

(6) PMS-C/B/C 

C*/C*/D 

(1) PDCS- 

 B/B/C 

(2) NAV-B/B/C 

(5) LIMITED 

 FMS-C/B/C 

C*/C*/D 

(1) PDCS- 

 B/B/C 

(2) NAV-B/B/C 

D/D/D 

(1) PDCS- 

 B/B/C 

(2) NAV-B/B/C 

B-737-300, 400, 

500 

(NON-EFIS) 

C*/C*/D 

(5) LIMITED 

 FMS-C/B/C 

C*/C*/D 

(5) LIMITED 

 FMS-C/B/C 

A/A/A 

(7) CROSS 

 MODEL- 

 A/A/B 

C/B/B (8) C/B/B 

B-737-300, 400, 

500 

(EFIS) 

(3) C*/C*/D 

(5) LIMITED 

 FMS-C/B/C 

(3) C*/C*/D 

(5) LIMITED 

 FMS-C/B/C 

(3) C/B/B A/A/A 

(7) CROSS 

 MODEL- 

 A/A/B 

(8) C/B/B 

(9) PFD/ND- 

 D/C/C 

TO AIRCRAFT 

B-737-600, 700, 

800, 900 

D/D/D D/D/D (8) C/B/B 

(9) PFD/ND- 

 D/C/C 

(8) C/B/B 

(9) PFD/ND- 

 D/C/C 

A/A/A 

(9) PFD/ND- 

 D/C/C 

(11) EDFCS- 

 C/C/C 
Page 8 

may allow credit or apply constraints to the use of a particular flight guidance control system 

(FGCS), flight management system (FMS), or electronic flight instrument system (EFIS), which 

is installed on aircraft. Footnotes are an appropriate means to address requirements that relate to 

specific systems (e.g., flight director and FMS) rather than a particular aircraft. In such instances,

generic knowledge or experience with the particular system may be readily transferable between 

related aircraft. Footnotes may also be used to set different requirements for initial training or 

checking rather than for recurrent training or checking. When necessary, footnotes are fully 

described in the body of the FSB report. 

(b) Other Limitations. Other limitations may occasionally be identified within a 

difference level (e.g. C*/C*/C). The asterisk following the difference level in such instances 

identifies a special requirement or limitation pertaining to a particular training method or device. 

Such notes typically relate to acceptable FSTDs when the FSTD evaluation and approval process 

or standard criteria of this AC are not available to address a particular situation appropriately. 

(10) MDRs for Aircraft with the Same or Different Type Certificate. A single FSB 

report and MDR table may apply to aircraft that are assigned the same type certificate with the 

same type rating. For example, a single MDR table may cover the A-318/319/320/321. A single 

FSB report and MDR table may also apply to different type certificated aircraft. For example, a 

single MDR table may cover the B-757 and B-767 or the A320, A330, and A340. When level E 

training is required for an aircraft with a same aircraft TC and an additional type rating is 

assigned, such as the B-747 and B-747-400, a single MDR table for all series of a typecertificated aircraft still applies. Minimum acceptable difference levels are assigned based on 

standard tests described in Appendix 3. 

c. Difference Levels. 

(1) General Description. Difference levels are formally designated levels of training 

methods or devices, checking methods, or means of maintaining currency that satisfy minimum 

difference requirements or type rating requirements. Difference levels specify FAA requirements 

proportionate to and corresponding with increasing differences between related aircraft. A range 

of five difference levels in order of increasing requirements, identified as A through E, are each 

specified for training, checking, and currency. MDRs are specified in terms of difference levels. 

Difference levels are used to credit knowledge, skills, and abilities applicable to an aircraft for 

which a pilot is already qualified and current, during initial, transition or upgrade training for 

other related aircraft. Operators, who conduct mixed fleet flying where credit is sought, should 

apply difference levels and address all mixed fleet flying requirements to ensure compliance with 

FAA requirements necessary to assure safe operations. 

(2) Basis for Levels. Difference levels apply when a difference with potential to affect 

fight safety exists between related aircraft. Differences may also affect knowledge, skills, or 

abilities required of a pilot. If no differences exist or if differences exist but do not affect 

knowledge, skills, abilities or flight safety, then difference levels are not assigned nor are they 

applicable to pilot training and qualification. When difference levels A through E apply, each 

difference level is based on a scale of differences in design features, systems, or maneuvers. In 

assessing the effects of differences, both flight characteristics and procedures are considered, 
Page 9 

since flight characteristics address handling qualities and performance, while procedures include 

normal and abnormal/nonnormal/emergency items. 

(3) Relationship Between Training, Checking, and Currency Levels. While 

particular aircraft are often assigned the same level (e.g., C/C/C) for training, checking, and 

currency, such assignment is not necessary. Levels may be assigned independently. For example, 

an aircraft may be assigned level C for training, level D for checking, and level C for currency 

(e.g., C/D/C). 

(4) Designation of Related Aircraft Type Ratings. Candidate aircraft having the same 

TC are assigned the same type rating if training differences are no greater than level D. 

Candidate aircraft of the same make having different TCs that have training differences no 

greater than level D will be assigned a different type rating that is considered a common type 

rating to the base aircraft. Candidate aircraft of the same make that have E level training 

difference requirements will be assigned a different type rating. A candidate aircraft with 

systems such as heads-up display (HUD), Enhanced Vision Systems (EVS), or Synthetic Visions 

Systems (SVS) may require Level E training without requiring a new type rating. The FSB, with 

the concurrence of the Air Transportation Division, AFS–200, will make these determinations. 

d. Training Difference Levels. 

(1) Level A Training. Level A difference training is that differences training between 

related aircraft that can adequately be addressed through self-instruction. Level A training 

represents a knowledge requirement that, once appropriate information is provided, 

understanding and compliance can be assumed. Level A compliance is achieved by such 

methods as issuance of operating manual page revisions, dissemination of operating bulletins, or 

differences handouts to describe minor differences in aircraft. Level A training is limited to the 

following situations: 

(a) A change that introduces a different version of a system/component for which 

the pilot has already shown the ability to understand and use (e.g., an updated version of an 

engine). 

(b) A change that results in minor or no procedural changes and does not adversely 

effect safety if the information is not reviewed or forgotten (e.g., a different vibration damping 

engine mount is installed, expect more vibration in descent; logo lights are installed, use is 

optional). 

(c) Information that highlights a difference, which is evident to the pilot, inherently 

obvious, and easily accommodated (e.g., different location of a communication radio panel, a 

different exhaust gas temperature limit that is placarded, or changes to nonnormal “read and do” 

procedures). 

(2) Level B Training. Level B difference training is applicable to aircraft with system 

or procedure differences that can adequately be addressed through aided instruction. At level B, 

aided instruction is appropriate to ensure pilot understanding, emphasize issues, provide a 

standardized method of presenting material, or aid retention of material following training. 

Level B aided instruction can utilize slide/tape presentations, computer based tutorial instruction, 
Page 10 

stand-up lectures or video tapes. Situations not covered under the provisions of level A training 

may require level B (or higher levels) if certain tests described in later paragraphs fail. 

(3) Level C Training. Level C differences training can only be accomplished through 

use of devices that are capable of systems training. Level C differences training is applicable to 

related aircraft having part task differences that affect skills or abilities and knowledge. Training 

highly integrated flight operations and maneuvers in “real time.” Level C may require selfinstruction or aided instruction, but cannot be adequately addressed by a knowledge requirement 

alone. Training devices are required to supplement instruction, ensure attainment or retention of 

pilot skills and abilities, and accomplish the more complex tasks, usually related to operation of 

particular aircraft systems. While level C systems knowledge or skills relate to specific rather 

than fully integrated tasks, performance of steps to accomplish normal, nonnormal, alternate, 

recall procedures, or maneuvers related to particular systems (e.g., flight guidance control 

systems/flight management systems) may be necessary. Typically, the minimum acceptable 

training media for level C training would be interactive computer-based training, cockpit systems 

FSTD, cockpit procedure trainers or part task trainers (e.g., FMS or traffic collision avoidance 

system (TCAS)). 

(4) Level D Training. Level D training can only be accomplished with devices capable 

of performing flight maneuvers and addressing full task differences of knowledge, skills, and/or 

abilities. Devices capable of flight maneuvers address full task performance in a dynamic real 

time environment. The devices enable integration of knowledge, skills, and abilities in a 

simulated flight environment, involving combinations of operationally oriented tasks and 

realistic task loading for each relevant phase of flight. Level D training, knowledge, and skills to 

complete necessary normal, nonnormal, alternate, or recall procedures are fully addressed for 

each related aircraft. Level D differences training requires mastery of interrelated skills that 

cannot be adequately addressed by separate acquisition of a series of knowledge areas or skills 

that are interrelated. The differences are not so significant that a full transition training course is 

required. If demonstrating interrelationships between the systems is important, use of a series of 

separate devices for systems training will not suffice. Training for level D differences requires a 

training device that has accurate, high fidelity integration of systems and controls, and realistic 

instrument indications. Level D training may also require maneuvers, visual cues, motion cues, 

dynamics, control loading or specific environmental conditions. Weather phenomenon such as 

low visibility, CAT III, or windshear may or may not be incorporated. Where simplified or 

generic characteristics of an aircraft type are used in devices to satisfy difference level D 

training, significant negative training must not occur as a result of the simplification. Typically, 

the minimum acceptable training media for level D training would be Flight Training Device 

level 6. 

(5) Level E Training. Level E training is applicable to candidate aircraft having such 

significant full task differences that require a “high fidelity” environment to attain or maintain 

knowledge, skills, or abilities. Training at level E can only be satisfied by the use of a FFS 

qualified at level C or D consistent with FAA criteria. Level E training, if done in an aircraft, 

should be modified for safety reasons where maneuvers can result in a high degree of risk (i.e., 

an engine set at idle thrust to simulate an engine failure). As with other levels, when level E 
Page 11 

training is assigned, suitable credit or constraints may be applied for knowledge, skills, and/or 

abilities related to other pertinent related aircraft. Credits or constraints are specified for the 

subjects, procedures, or maneuvers shown in FSB reports and are applied through the ODR table. 

NOTE: Training differences levels specified by the FSB represent minimum 

requirements. Operators may use a device associated with a higher 

difference level to satisfy a training differences requirement. For example, if 

level C differences are assessed due to installation of a different FMS, 

operators may train pilots using the FMS installed in a FFS as a system 

trainer if a dedicated part task FMS training device is not available. 

e. Checking Difference Levels. 

(1) Initial and Recurrent Checking. Difference checking addresses any pertinent pilot 

certification that includes type rating checks, proficiency checks, Advanced Qualification 

Program (AQP) evaluations, and any other checks specified by FSB reports. Initial and recurrent 

checking levels are the same unless otherwise specified by the FSB. In certain instances, it may 

be possible to satisfactorily accomplish recurrent checking objectives in devices that do not meet 

initial checking requirements. In such instances, the FSB may recommend certain devices that do 

not meet initial check requirements for use to administer recurring checks. The POI/Training 

Center Program Manager, in coordination with the FSB, may require checking in the initial 

level device when doubt exists regarding pilot competency or program adequacy. 

(2) Level A Checking. Level A checking indicates that no check related to differences 

is required at the time of differences training. A pilot is responsible for knowledge of each 

related aircraft flown. Differences items should be included as an integral part of subsequent 

recurring proficiency checks. 

(3) Level B Checking. Level B checking indicates that a “task” or “systems” check is 

required following transition and recurring differences training. Level B checking typically 

applies to particular tasks or systems such as FMS, TCAS, or other individual systems or related 

groups of systems. 

(4) Level C Checking. Level C checking requires a partial proficiency check using a 

device suitable for meeting level C (or higher) differences training requirements following 

transition and recurrent differences training. The partial check is conducted relative to particular 

maneuvers or systems designated by the FSB. Example of a level C check: Evaluation of a 

sequence of maneuvers demonstrating a pilot’s ability to use a FGCS or FMS. An acceptable 

scenario would include each relevant phase of flight that uses the FGCS or FMS. 

(5) Level D Checking. Level D checking requires a partial proficiency check for one or 

more related aircraft following both transition and recurrent training. The partial proficiency 

check covers the particular maneuvers, systems, or devices designated by the FSB. Level D 

checks are performed using scenarios representing a “real time” flight environment and devices 

permitted for level D differences training. A full proficiency check is typically conducted on the 

base aircraft, and a partial proficiency check on the related aircraft, covering all pertinent 

differences. 
Page 12 

(6) Level E Checking. Unless specified, level E checking requires that a full proficiency 

check be conducted in a level C or D FFS. As with other levels, when level E checking is 

assigned, suitable credit or constraints may be applied for knowledge, skills, and/or abilities 

related to other pertinent related aircraft. Credits or constraints are specified for the subjects, 

procedures, or maneuvers shown in FSB reports and are applied through the ODR table. 

NOTE: Assignment of level E checking requirements alone does not result in 

assignment of a separate type rating. Only the assignment of level E training 

requirements may result in assignment of a separate type rating. 

f. Currency Difference Levels. The term “currency” as used in this AC addresses recent 

experience necessary for safe operation of aircraft as designated by the FSB. Currency issues not 

specified by the FSB are covered by regulation.

(1) Level A Currency. Level A currency is considered common to each related aircraft. 

Thus, assessment or tracking of currency for separate related aircraft is not necessary or 

applicable. Maintenance of currency in any one related aircraft or a combination of related 

aircraft will suffice for any other related aircraft. 

(2) Level B Currency. Level B currency is “knowledge related” currency, typically 

achieved through self-review by individual pilots for a particular aircraft. Self-review is usually 

accomplished by review of material provided by the operator to pilot. Such currency may be 

undertaken at an individual pilot’s initiative; however, the operator will identify the material and 

the frequency or other situations in which the material should be reviewed. Self-review may be 

based on manual information, bulletins, aircraft placards, memos, class handouts, videotapes, or 

other memory aids that describe the differences, procedures, maneuvers, or limits for the 

pertinent aircraft that pilots are flying. Examples of acceptable compliance with level B currency 

are: 

(a) The issuance of a bulletin that directs pilots to review specific operating manual 

information before flying a related aircraft. Level B currency may be regained by review of 

pertinent information to include bulletins, if that related aircraft has not been flown within a 

specified period (e.g., fly that related aircraft or have completed a review of the differences in 

limitations and procedures within a specified number of days). 

(b) Pilot certification on a dispatch release that they have reviewed pertinent 

information for a particular related aircraft to be flown on that trip. Level B currency cannot, 

however, be achieved solely by review of class notes taken by and at the initiative of an 

individual pilot unless the adequacy of those notes is verified by the operator. 

(3) Level C Currency. Level C currency is applicable to one or more designated 

systems or procedures, and relates to both skill and knowledge requirements. An example would 

be establishment of FMS currency, flight guidance control system currency, or other particular 

currency that is necessary for safe operation of a related aircraft. Establishment of level C for a 

related aircraft with an FMS would typically require a pilot to fly that related aircraft within the 

specified period of time or re-establish currency. Currency constraints for level C are established 
Page 13 

by the FSB. When level C currency applies, pertinent level B currency will also be addressed. 

Examples of methods acceptable for addressing level C currency are: 

(a) Pilot scheduling practices resulting in a pilot being scheduled to fly a related 

aircraft with the pertinent system/procedure within the specified period of time; 

(b) Tracking of an individual pilot’s flying of related aircraft to ensure that the 

particular system/procedure has been flown within the specified period of time; 

(c) Use of a higher level method (level D or E currency); or 

(d) Other methods as designated or found acceptable by the FSB. 

(4) Re-establishing Level C Currency. When currency is lost, currency may be reestablished by completing required items using a device equal to or higher than that specified for 

level C differences training and checking. Other means to re-establish currency include flights 

with an appropriately qualified check airman/instructor, completion of proficiency training, or a 

proficiency check. In some instances, a formal refamiliarization period in the actual aircraft with 

the applicable system operating while on the ground may be acceptable if permitted by the FSB. 

Such refamiliarization periods are completed using an operator-established procedure under the 

supervision of a pilot designated by the operator. In the case of a noncurrent SIC, a designated 

pilot-in-command (PIC) may be authorized to accompany a pilot to re-establish currency. 

(5) Level D Currency. Level D currency is related to designated maneuvers, and 

addresses knowledge and skills required for performing aircraft control tasks in real time, with 

integrated use of associated systems and procedures. Level D currency may also address certain 

differences in flight characteristics including performance of any required maneuvers and related 

normal/abnormal/emergency procedures for a particular related aircraft. A typical application of 

level D currency is to specify selected maneuvers, such as takeoff, departure, arrival, approach, 

or landing, which are to be performed using a particular FGCS and instrument display system. 

Either a pilot must fly a related aircraft equipped with the FGCS and particular display system 

sufficiently often to retain familiarity and competence within the specified currency period, or 

currency must be re-established. Currency constraints for level D are established by the FSB. 

When level D currency applies, pertinent level B and level C currency must also be addressed. 

Examples of methods acceptable for addressing level D currency are: 

(a) Tracking of flights by a particular pilot in a particular related aircraft to assure 

experience within the specified currency period. 

(b) Tracking the completion of specific maneuvers based on logbook entries, 

Aircraft Communication Addressing and Reporting System (ACARS) data, or other reliable 

records to assure experience within the specified currency period. 

(c) Scheduling of aircraft or pilots to permit currency requirements to be met with 

verification that each pilot has actually accomplished the assigned or an equivalent schedule. 
Page 14 

(d) Completion of pilot certification, proficiency check, proficiency training, AQP 

evaluations, or other pertinent events in which designated maneuvers are performed in a FFS 

acceptable for level D currency. 

(e) Use of a higher level method (level E currency). 

(f) Other methods as designated or found acceptable by the FSB. 

(6) Re-establishing Level D Currency. When currency is lost, currency may be reestablished by completing pertinent maneuvers using a device equal to or higher than that 

specified for level D differences training and checking. Other means to re-establish currency 

include flight with an appropriately qualified check airman during training or in line operations, 

completion of proficiency training, or a proficiency check. 

(7) Level E Currency. Level E currency may specify system, procedure, or maneuver 

currency item(s) necessary for safe operations, as identified by the FSB, to be accomplished in a 

Level C/D FFS for that related aircraft. FSB provisions related to takeoff and landing are applied 

in a way that addresses needed system or maneuver experience. For example, if FGCS, FMS, 

EFIS, navigation, or other system or maneuver experience is the basis for a currency 

requirement, approval of an operator’s program at level E includes the use of those systems in 

conjunction with satisfying takeoff and landing requirements. In this instance, making three FSS 

takeoffs and landings in VFR closed traffic without using the FGCS, EFIS, or FMS may not be 

sufficient to meet level E currency requirements. 

NOTE: Assignment of level E currency requirements does not result in 

assignment of a separate type rating. Only the assignment of level E training 

requirements may result in assignment of a separate type rating. 

(8) Re-establishing Level E Currency. When currency is lost, currency may be reestablished by completing pertinent maneuvers using a device specified for level E differences 

training and checking. Other means to re-establish currency include flight with an appropriately 

qualified check airman during training or in line operations, completion of proficiency training, a 

proficiency check, or AQP evaluation. 

(9) Competency Regarding Abnormal/Nonnormal/Emergency Procedures.

Competency for nonnormal maneuvers or procedures is generally addressed by checking 

requirements; however, in particular abnormal/nonnormal/emergency maneuvers or procedures 

may not be mandatory for checking or training. In this situation, it may be necessary to periodically 

practice or demonstrate those maneuvers or procedures even though it is not necessary to complete 

them during each check. In such instances, the FSB may specify a currency requirement for 

training or checking applicable to abnormal/nonnormal/emergency maneuvers or procedures that 

are to be performed. This is to assure that extended periods of time do not elapse in a series of 

repeated training and checking events in which significant maneuvers or procedures may never be 

accomplished. When an abnormal/nonnormal/emergency maneuver or procedure is not mandatory 

and is not accomplished during each proficiency training or proficiency check, but is still important 

to occasionally practice or demonstrate, the FSB may establish a currency requirement. When 

designated by the FSB, these currency requirements identify each abnormal/nonnormal/ 
Page 15 

emergency maneuver or procedure, the currency level applicable, and an applicable time period or 

any other necessary/appropriate constraints. 

(10) Difference Level Summary. Difference levels are summarized in Figure 2 below

for training, checking, and currency. Complete descriptions of difference levels for training, 

checking and currency are given above. 

FIGURE 2. DIFFERENCE LEVEL TABLE 

DIFFERENCE 

LEVEL 

TRAINING CHECKING CURRENCY 

A Self instruction Not applicable 

(or integrated with next 

proficiency check) 

Not applicable 

B Aided instruction Task or system check Self review 

C Systems devices Partial check using 

device 

Designated system 

D Maneuver devices* Partial proficiency check 

using device* 

Designed maneuver(s) 

E FFS c/d or aircraft 

# 

Proficiency check using 

FSS c/d 

Or aircraft * 

Designed maneuver(s) 

except takeoff and landings 

# = New type rating is normally assigned 

* = FFS or aircraft may be used to accomplish specific maneuvers 

g. Operating Experience (OE) for Aircraft. 

(1) Credits or Constraints. OE must meet the applicable requirements of the CFR Part 

121. 

h. Supervised Line Flying (SLF). Experience associated with the introduction of 

equipment or procedures requiring post qualification skill enhancement during which a pilot 

occupies a specific pilot position and performs particular assigned duties for that pilot position 

under the supervision of a pilot instructor or check airman qualified for the operator. One or 

more of the reasons described below may apply: 

(1) Introduction of new systems (e.g., Automatic Dependent Surveillance Broadcast 

(ADS-B), runway area advisory system (RAAS), etc). 

(2) Introduction of new operations (e.g., oceanic operations, Extended Operations with 

Two-Engine Airplanes (ETOPS)). 

(3) Experience for a particular pilot position (e.g., PIC, SIC). 

(4) Special characteristics (e.g., affects of unique airports, mountainous areas, unusual 

weather, special air traffic control procedures, or nonstandard runway surfaces) on this aircraft. 
Page 16 

i. Recency of Experience. Credit towards the recency of experience requirements of 

14 CFR Part 121.1229 may be permitted for takeoffs and landings performed in related aircraft 

as provided by CTLC. CTLC will be validated through the FSB process and must be carried out 

in accordance with (IAW) the operator’s CTLC approved program. 

j. Operator Difference Requirements (ODR). 

(1) ODR Purpose. If differences exist within an operator’s fleet, which affect pilot 

knowledge, skills, or abilities pertinent to systems or procedures, ODR tables provide a uniform 

means for operators to comprehensively manage difference programs and provide a basis for 

FAA approval of mixed fleet flying. 

(2) ODR Content. ODRs identify a base aircraft, describe differences between aircraft, 

and show an operator’s methods of compliance with FAA requirements. The FAA approves an 

operator’s initial ODR and each subsequent revision for the following: 

(a) Base Aircraft. ODRs identify an aircraft or group of aircraft (aircraft of the 

same series with minor configuration differences) within an operator’s fleet as a base aircraft. 

The base aircraft serves as a reference for comparison with candidate aircraft. Selection criteria 

and characteristics of base aircraft are described in paragraphs 6c and 7c. 

(b) Candidate/Related Aircraft. ODRs identify particular aircraft flown by an 

operator within each fleet. ODRs consider only those aircraft and combinations of aircraft 

actually flown by that operator. ODRs describe differences within an operator’s fleet between the 

base aircraft and other related aircraft. 

(c) Significance of Differences. Differences are described in summary form and 

are categorized by differences in design features, systems, and maneuvers. Differences are 

evaluated relative to their effect on either flight characteristics, pilot skills, and/or procedures. 

Procedures consider normal, nonnormal, alternate, and recall items. Limitations are considered in 

conjunction with normal procedures. 

(d) Compliance Methods. ODRs show how each operator’s program addresses 

differences, through description of training, checking, or currency methods for each fleet. ODRs 

describe the specific or unique constraints or credits applicable, and any precautions necessary to 

address differences between aircraft. ODRs must comply with and be just as or more restrictive 

than FAA MDRs and other FSB provisions if such provisions are part of the operator approved 

training program. Constraints or credits may be applied to all aircraft in a fleet or only to certain 

aircraft. Constraints or credits may address FSTDs, checking and currency methods, knowledge, 

skills, procedure maneuvers, or any other factors that apply to or are necessary for safe 

operations. Training, checking, and currency compliance methods are proposed and revised by 

each operator consistent with ODR examples from a variety of sources that are acceptable to the 

FAA. ODR examples are found in FSB reports. 

(3) Standard ODR Format. ODRs are depicted in tables in summarized form. If

necessary, any explanation of details about differences, constraints and credits, precautions or 

compliance methods are included in attachments or appendices to ODR tables or are cross 

referenced to other operator documents. Figure 3 shows the general format for ODR tables, 
Page 17 

including examples of design, systems, and maneuver differences. The far-left column lists 

design, system, or maneuver differences that are pertinent. The “Remarks” column summarizes 

specific areas or items of difference. The “Flight Characteristics” and “Procedural Change” 

columns identify what (if any) difference effects are noted. The “Compliance Methods” section 

of the table notes the particular operator’s approved means of compliance with FAA MDR 

provisions. The following abbreviations apply: 

• ACFT - Aircraft. 

• AFDS - Auto Flight Display System. 

• AVT - Audio Visual Tapes. 

• CBT - Computer Based Training. 

• EFIS - Electronic Flight Instrument System. 

• EICAS - Engine Indicating and Crew Alerting System. 

• FSTD - Full Flight Simulator (FFS) or Flight Training Device (FTD). 

• FLT CHAR - Flight Characteristics. 

• FMC - Flight Management Computer. 

• FMS - Flight Management System. 

• PROC CHNG - Procedural Changes. 

• SU - Stand Up Instruction. 
Page 18 

FIGURE 3-1. DESIGN OPERATOR DIFFERENCE REQUIREMENTS TABLE 

EXAMPLE 

CURR 

B 

CHKG/CURR 

FLT 

CHK 

LVL 

E 

LVL 

D 

LVL 

C 

LVL 

B 

AVT/ 

SU/ 

CBT 

AVT/ 

SU/ 

CBT 

AVT/ 

SU/ 

CBT 

COMPLIANCE METHOD 

TRAINING 

LVL 

A 

PROC 

CHNG 

NO NO NO 

FLT 

CHAR 

MINOR 

NO NO 

REMARKS 

- BODY EXTENSION 104” - WING TIP EXTENSION 14” - DORSAL FIN - w/STC ST01219SE, BLENDED WINGLET - ADDITION OF FMC/AFDS/AT/IRS ETC. - GROWTH RELATED CHANGES 

DESIGN OPERATOR DIFFERENCE REQUIREMENTS TABLE 

DIFFERENCE AIRCRAFT: 737-300 BASE AIRCRAFT: 737-200 ADVANCED APPROVED BY (POI): 

DESIGN FEATURE 

AIRPLANE CONFIGURA-TION PANEL LAYOUT WEIGHTS 
Page 19 

FIGURE 3-2. SYSTEMS OPERATOR DIFFERENCE REQUIREMENTS TABLE 

EXAMPLE 

CURR 

D 

90 

DAYS 

+ 

3 FLT 

SEG. 

CHKG/CURR 

FLT 

CHK 

C*+OE 

LVL 

E 

LVL 

D 

LVL 

C 

CBT/ 

FMS/ 

AT 

LVL 

B 

AVT/ 

SU 

AVT 

AVT/ 

SU 

AVT/ 

SU 

AVT/ 

SU 

COMPLIANCE METHOD 

TRAINING 

LVL 

A 

PROC 

CHNG 

YES YES 

NO 

YES YES 

FLT 

CHAR 

NO NO NO NO NO 

REMARKS 

- RECIRC FAN REPLACES GASPER FAN - 3 POSITION PACK SWITCH - FWD OUTFLOW VALVE LIGHT DELETED - EQUIPMENT COOLING FAN LIGHT - ADDITIONAL FAN INSTALLED (EFIS ONLY) - DISTRIBUTION: MINOR CHANGES - SP-300 AFDS REPLACES SP-77/SP-177 - AUTOTHROTTLE ADDED* - AUTOLAND CAPABILITY ADDED* (*ONLY WHEN COMPARED TO SP-77 AIRPLANES) - LNAV/VNAV - TO/GA MODE - MINOR CHANGES IN POWER DISTRIBUTION - CANNISTER OPTION ONLY* - NEW CREW MASKS* (*OPTION ON SOME -200 AIRPLANES) - DUAL-LOOP DETECTION SYSTEM - MINOR EXTING. EQUIP. CONFIG CHANGE - TWO SQUIBS PER BOTTLE 

SYSTEMS OPERATOR DIFFERENCE REQUIREMENTS TABLE 

DIFFERENCE AIRCRAFT: 737-300 BASE AIRCRAFT: 737-200 ADVANCED APPROVED BY (POI): 

SYSTEM 

21 AIR COND. & PRESSURIZATION 22 AUTO-FLIGHT 24 ELECTRICAL 25 EMERGENCY EQUIPMENT 26 FIRE PROTECTION 
Page 20 

FIGURE 3-2. SYSTEMS OPERATOR DIFFERENCE REQUIREMENTS TABLE 

EXAMPLE (CONTINUED) 

CURR 

CHKG/CURR 

FLT 

CHK 

LVL 

E 

LVL 

D 

LVL 

C 

LVL 

B 

AVT/ 

SU 

(CBT/ 

AVT/ 

SU) 

AVT/ 

SU 

COMPLIANCE METHOD 

TRAINING 

LVL 

A 

PROC 

CHNG 

YES 

(YES 

MINOR) 

YES 

FLT 

CHAR 

MINOR 

NO 

REMARKS 

- ADD’L SPOILERS ADDED - ELECTRIC AIL TRIM - DUAL CHANNEL MACH TRIM; TEST BUTTON DELETED - SPEED TRIM ADDED - STAB TRIM BRAKE DELETED - TWO SPEED STAB TRIM - DIFFERENT STAB TRIM RANGE - ELECTRIC STAB TRIM OVERRIDE - ELECTRIC RUDDER TRIM - AUTOSLAT SYS. ADDED - TE FLAP PLACARD SPEEDS - CERTIFIED T/O FLAP SETTINGS - RUDDER SYSTEM ENHANCEMENT - (OPTION: BLENDED WINGLET W/  SPEED BRAKE LOAD ALLEVIATION) - CONTINUOUS FUEL HEAT SWITCHES DELETED - FILTER BYPASS LIGHT REPLACES ICING LIGHT - FUEL CAPACITY INCREASED - GND XFER OF FUEL - AUX TANK (OPTIONAL) 

SYSTEMS OPERATOR DIFFERENCE REQUIREMENTS TABLE 

DIFFERENCE AIRCRAFT: 737-300 BASE AIRCRAFT: 737-200 ADVANCED APPROVED BY (POI): 

SYSTEM 

27 FLIGHT CONTROLS 28 FUEL 
Page 21 

FIGURE 3-2. SYSTEMS OPERATOR DIFFERENCE REQUIREMENTS TABLE 

EXAMPLE (CONTINUED) 

CURR 

CHKG/CURR 

FLT 

CHK 

LVL 

E 

LVL 

D 

LVL 

C 

LVL 

B 

AVT/ 

SU 

AVT/ 

SU 

AVT/ 

SU 

AVT/ 

SU 

COMPLIANCE METHOD 

TRAINING 

LVL 

A 

PROC 

CHNG 

YES YES YES 

NO 

FLT 

CHAR 

NO NO NO NO 

REMARKS 

- LANDING GEAR XFER UNIT - SYS A & B SOURCES AND COMPONENTS CHANGED; A & B INDEPENDENT - GROUND INTERCONNECT DELETED - AUTOSLAT PTU - THRUST REVERSER - ONE ON EACH SYSTEM - B QUANTITY GUAGE ADDED  - STBY RUDDER ON LIGHT - ENG INLET ANTI-ICE DELETED - WING ANTI-ICE OPERATION ON GROUND PERMITTED* (*OPTION ON SOME -200 AIRPLANES) - EFIS (AS INSTALLED) - ADI/HIS (AS INSTALLED) - NAV SWITCH (AS INSTALLED) - NORM/ALT REPLACES A & B SYS BRAKES - PAIRED WHEEL ANTI-SKID PROTECTION ON ALT BRAKES - TIRE SCREEN DELETED* - NO TOUCHDOWN OR LOCKED WHEEL PROTECTION ON ALT BRAKES - SINGLE ANTI-SKID SWITCH (*OPTION ON SOME -200 AIRPLANES) 

SYSTEMS OPERATOR DIFFERENCE REQUIREMENTS TABLE 

DIFFERENCE AIRCRAFT: 737-300 BASE AIRCRAFT: 737-200 ADVANCED APPROVED BY (POI): 

SYSTEM 

29 HYDRAULIC 30 ICE & RAIN PROTECTION 31 FLIGHT INSTRUMENTS 32 LANDING GEAR 
Page 22 

FIGURE 3-2. SYSTEMS OPERATOR DIFFERENCE REQUIREMENTS TABLE 

EXAMPLE (CONTINUED) 

CURR 

D 

90 

DAYS 

+ 

3 FLT 

SEG. 

B 

CHKG/CURR 

FLT 

CHK 

C* 

+ 

OE 

C* 

LVL 

E 

LVL 

D 

LVL 

C 

CBT/ 

FMS/ 

AT 

FMS/ 

AT 

LVL 

B 

AVT/ 

SU 

AVT 

AVT/ 

SU 

AVT/ 

SU 

AVT/ 

SU 

AVT/ 

SU 

AVT/ 

SU 

COMPLIANCE METHOD 

TRAINING 

LVL 

A 

PROC 

CHNG 

YES YES 

NO 

YES YES 

NO NO 

FLT 

CHAR 

NO NO NO NO NO 

MINOR 

NO 

REMARKS 

- ADDITIONAL SYS ANNUNCIATOR LIGHTS ADDED - GPWS MODE 6 WINDSHEAR OPTION* (* OPTION ON SOME -200 AIRPLANES) - FMCS ADDED - IRS ADDED - ANCDU - DISTRIBUTION MINOR CHANGE - CFM-56 ENGINES - NEW INDICATORS - CASCADING VANES TYPE REVERSER WITH AUTO RESTOW - PMC ADDED - IGN SELECT SWITCH - AUTOMATIC RECOVERY AVAILABLE IF IN DUAL CHANNEL - FLIGHT DIRECTOR GUIDANCE AVAILABLE (OPTIONAL) - CHANGED - GROWTH RELATED CHANGES 

SYSTEMS OPERATOR DIFFERENCE REQUIREMENTS TABLE 

DIFFERENCE AIRCRAFT: 737-300 BASE AIRCRAFT: 737-200 ADVANCED APPROVED BY (POI): 

SYSTEM 

33 WARNING 34 NAVIGATION 36 PNEUMATICS 73, 74, 77, 80 POWER PLANT WINDSHEAR EQUIPMENT PERFORMANCE LIMITATIONS 
Page 23 

FIGURE 3-3. MANEUVER OPERATOR DIFFERENCE REQUIREMENTS TABLE 

EXAMPLE CURR D 90 DAYS 

+ 

3 FLT 

SEG. 

CHKG/CURR 

FLT 

CHK 

C* 

+ 

OE 

C* 

LVL 

E 

LVL 

D 

LVL 

C 

FMS/ 

AT 

FME/ 

AT 

LVL 

B 

AVT/ 

SU 

AVT/ 

SU 

COMPLIANCE METHOD 

TRAINING 

LVL 

A 

PROC 

CHNG 

SEE 

APP 

SEE 

APP 

FLT 

CHAR 

NO NO 

REMARKS 

- OPTIONAL USE OF AFDS, AND A/T (ALSO AN OPTION FOR -200 AFCS AIRPLANES) - OPTIONAL USE OF FMCS - OPTIONAL USE OF AFDS, AND A/T (ALSO AN OP;TION FOR -200 AFCS AIRPLANES) - OPTIONAL USE OF FMCS 

MANEUVER OPERATOR DIFFERENCE REQUIREMENTS TABLE 

DIFFERENCE AIRCRAFT: 737-300 BASE AIRCRAFT: 737-200 ADVANCED APPROVED BY (POI): 

MANEUVER 

NORMAL TAKEOFF, CLIMB, CRUISE, DESCENT, INSTRUMENT APPROACHES, LANDING NON-NORMAL MANEUVERS 
Page 24 

(4) ODR Approval, Distribution, and Availability. ODRs are approved for each fleet by 

an operator’s FAA POI in accordance with FSB report recommendations. ODRs must be 

prepared, reviewed, approved and then used to govern training before start of operations. The 

operator retains approved ODRs with a duplicate copy as part of FAA certificate-holding district 

office (CHDO) records. 

(5) ODR Revision. ODR tables are revised by operators and re-approved by the FAA 

when fleet characteristics change or when compliance methods change. Fleet characteristic 

changes include redesignation of base aircraft, modification of aircraft, addition of aircraft, 

change of aircraft, or phaseout of aircraft. Changes in compliance methods refer to introduction 

of new or different training methods, contracting for use of different FSTDs, revision of 

checking or currency methods, or other such changes. Revisions to ODRs are also prepared, 

reviewed, and approved before operating. 

NOTE: Paragraph 6 describes the development, approval, and application of 

ODR tables to individual operator’s programs. Paragraph 7 describes FAA 

review and approval of programs by POIs. 

5. FORMULATION OF FSB REPORTS, MDRs, AND DESIGNATION OF TYPE 

RATINGS. 

a. Formulation Process Overview. The process for FAA formulation and revision of 

training, checking, currency, and type rating requirements is shown in Figure 4. The process 

determines which information is required for an aircraft; it includes a proposal for requirements, 

tests, and evaluations of the proposed requirements; it then finalizes, applies, and implements the 

FSB recommendations. Applicants propose MDRs, examples of ODRs, and any other FSB 

provisions that are necessary. Proposals for requirements are based on design objectives, 

analysis, evaluation of OE, other programs that have been proved acceptable to the FAA, or 

other methods. Setting of requirements is based on an objective set of tests and standards, 

analysis of results, and FAA judgments considering OE. The applicant and the FAA prepare and 

conduct standardized tests. The applicant provides test support, and the FSB conducts the 

evaluation. The FSB, in conjunction with the applicant, evaluates the results, and the FAA 

formulates proposed minimum requirements. The FSB sets final recommended requirements by 

specifying MDRs and other FSB provisions. An FSB report that describes findings is 

disseminated to FAA field offices and posted on the operations specifications (OpSpecs) 

Web site for application to specific operator’s programs. The formulation and application 

process of FSB provisions starts at the time a new aircraft is proposed to the FAA and continues 

throughout the fleet life of that aircraft. For aircraft already in service the process may be 

initiated when significant modifications are proposed, a new piece of equipment (e.g., a HUD) 

requiring operational evaluation is introduced and requested by operators, or when mixed fleet 

flying takes place. The FAA addresses periodic revisions of requirements when necessary, and 

revisions are initiated by the FAA and applicants as needed. 

b. Proposals for MDRs, Example ODRs, and Special Requirements. 

(1) When Proposals are Necessary. The FAA usually determines when proposals are 

necessary and advises the applicant what information is needed, in conjunction with aircraft type 
Page 25 

certification or supplemental certification programs. Necessary information may include MDRs for 

related aircraft or other elements of the FSB reports. The applicant considers existing MDRs and 

existing or proposed ODRs. 

(2) Proposal Formulation. An operator, manufacturer, or an organization that modifies 

airplanes proposes a new design or modification. The applicant will then do the following: 

(a) Formulate necessary information for training, checking, and currency for the aircraft 

in proposals for MDRs and example ODRs. 

(b) Prepare example ODR tables for candidate aircraft to support development of a 

proposed MDR. These examples represent proposals for programs for those specific aircraft and 

configurations that the FAA could approve. 

(c) Identify related aircraft for the proposed MDR table. 

(d) Formulate any necessary tests to assess difference levels and associated training, 

checking, and currency requirements for incorporation in the MDR table. 

(e) Identify interpretations of possible test results. The FAA and the applicant will then 

reach an agreement on specific tests, devices, and schedules to be used for the test program. 

(f) The applicant submits proposals for the following items to the FAA, as necessary: 

• MDRs 

• Example ODRs 

• Tests and criteria to be used 

• Other supporting information associated with training, checking, or currency 

programs 

c. Difference Level Tests. A sequence of five standard tests, described in Appendix 3, is used to 

set MDRs, minimum acceptable training programs, other FSB provisions, and define type rating 

requirements. One or more of these tests are applied depending on the difference level sought, and the

success of any previous tests used in identifying MDRs. Only those tests needed are used to establish 

minimum requirements. The outcome of these tests, and any resulting difference levels that apply, 

establish minimum requirements for training, checking, currency, and type ratings. The FAA will 

establish an additional type rating if it is determined during this testing that the assignment of a level E 

differences training is required. 

NOTE: One additional test, the T6 test, can be used to establish CTLC between 

related aircraft, when not previously demonstrated in a T2 test. 

(1) Steps in the Testing Process. The typical steps of the testing process are as follows: 
Page 26 

(a) The applicant develops representative training programs, difference programs, and 

necessary supporting information, as needed. 

(b) The applicant identifies proposed MDRs and example ODRs. 

(c) The applicant proposes and the FAA determines which tests and criteria apply. 

(d) The applicant proposes and the FAA determines which aircraft, simulation devices, 

or analyses are needed to support testing. 

(e) The applicant makes a proposal to the FAA, and agreement is reached on test 

procedures, schedules, and specific interpretation of possible results. 

(f) Tests are conducted and results evaluated. 

(g) The FSB draft minimum requirements are formulated. 

NOTE: If the candidate aircraft is anticipated to have no greater than level A or 

B differences with the base aircraft, the FSB may elect to directly apply a T1 test 

for equivalency. 

(2) Test Purpose and Application. A summary of the purpose and application of each of the 

six difference tests is shown in Figure 5. 

(3) Test Relationships and Applications. This process is followed whenever a new aircraft 

is proposed, when significant changes are proposed, or when revisions to existing requirements are 

needed as a result of requests for change or operating experience. The test process relationships, the

sequence of conducting tests when more than one test is needed, and application of test outcomes are 

shown in Figure 6. The start of the process is shown at the top of Figure 6. 

a. When a new aircraft is certified and is not compared with an existing aircraft, the aircraft is 

evaluated using the T5 test to determine the effectiveness of the manufacturer training and evaluation

plan. A type rating is assigned as a result of the evaluation. 

b. When two aircraft with the same type certificate are compared, a T1 or T2/T3 test is used to 

determine the level of differences between the two aircraft. The result can be the assignment of a same 

type rating if no greater than Level D differences exist or the assignment of a different type rating if 

Level E differences exist. 

c. When two aircraft with different type certificates are compared, a T2/T3 test is used to 

determine the level of differences between the two aircraft. An example of this is a determination of B, 

C, D, or E differences between the two aircraft. 

(4) Test Failures and Retesting. Generally, failures do not have paths back to lower levels. 

T3 test failure at level C can lead to subsequent passage at C (after modification of the system, 

operational procedures, or training and retesting) or D. Similarly, failure at level D can subsequently 

lead to either D (after modification of the system, operational procedures, or training and retesting) or 

E, but not C. Failure at level E can only lead to retesting with increased programs, improved programs, 
Page 27 

or improved devices since there is no higher level. T5 test failure paths do not lead back to level C or 

level D. However, subsequent new programs do not preclude making a proposal at a lower differences 

level if technology changes, aircraft redesign takes place, training methods significantly change, or 

device characteristics and effectiveness change. 

(5) Same and Common Type Rating Tests. Aircraft seeking same or common type rating 

will follow the path in Figure 6 from the top left of Figure 6 through T1 or T2 and T3 tests resulting in 

the assignment of level A, B, C, or D differences. 

(6) “Currency” Tests. T4 currency tests are not shown in Figure 6 because they are 

necessary only when the applicant seeks relief from system, procedural, and maneuver currency 

requirements set by the FSB. 

(7) Detailed Test Specifications. A detailed specification for the evaluation process and tests 

to establish difference levels is described in Appendix 3. 

d. FSB Assessments and Proposal Formulation. The FSB assesses the applicant’s proposals, 

test results, analysis, and any other relevant factors to formulate a draft FSB report, which includes

MDRs and other pertinent training, checking, currency requirements. The FSB either validates the 

applicant’s proposed MDRs, training programs, and other information, or generates alternate 

requirements, which may include more stringent requirements, additional training, additional testing, 

etc. 
Page 28 

FIGURE 4. MASTER REQUIREMENTS FORMULATION 
Page 29 

FIGURE 5. TEST DEFINITIONS

TEST PURPOSE APPLICATION 

T1 Establishes functional equivalence Sets levels A/B 

T2 Handling qualities comparison Pass permits T3, and A/B/C/D; failure sets 

level E and requires T5 

T3 Evaluate differences and sets 

training/checking requirements 

Pass sets levels A/B/C/D; failure sets 

level E and requires T5 

T4 Revises currency requirements Used to adjust FSB provisions—if needed 

T5 Sets training/checking for new or “E” 

ACFT Sets level E 

T6 Evaluation for CTLC Sets recency of experience requirements 

Note: Expanded descriptions are contained in Appendix 3. 
Page 30 

FIGURE 6. “T” TESTS 

1 THRU 5 

 START 

 T1 

Req’d 

Candidate 

Level E? 

 T1 T2 

 T3 

Req”d 

LVL 

A or B 

 T3 

T5 LEVEL E 

No Commonality 

or 

T5 LVL E 

With B/C/D 

Commonality

LVL D 

Differences 

LVL C 

Differences 

LVL B 

Differences 

LVL A 

Differences 

LVL E 

Differences 

New T/R 

No 

Fail

Pass 

Waive T1 

Pass

Fail

Pass

Fail

Yes

SAME OR COMMON TYPE RATING 

COMMOM TYPE RATING REQUIRES 

SEPARATE TYPE RATING 

INDORSEMENT 

No
Page 31 

 

 

e. Comments Solicited. The FSB proposal is circulated with interested parties representing 

the manufacturer, operators, and other pertinent FAA organizations such as engineering, flight 

test, pilots’ associations, and other aviation representatives for comment, relevant information, 

and recommendations. 

f. FSB Final Determinations and Findings. 

(1) FSB Determinations. Any comments submitted to the FAA are reconciled, and final 

FSB determinations are made. Specification of MDRs, example ODRs, acceptable training 

programs, and other FSB provisions are completed. Any necessary pilot checking or currency 

provisions are identified. Assignment of any necessary type rating(s) is made. 

(2) Basis for FSB Judgments. FSB judgments are based on review of the applicant’s 

supporting documentation, proposed ODR tables, test results, and any other pertinent 

information, such as FAA policies, OE, and results of other similar FSB evaluations. 

Specifically, FSB report provisions are based on the following: 

(a) Appropriate Data, Evaluation, or Tests. Testing may include aircraft 

demonstration, simulation tests, device testing, or analysis. 

(b) Direct Experience. The industry may have substantial experience with 

successful operational programs, which can be useful in the assignment of minimum difference 

level requirements. This experience may include particular training devices, 

training/checking/currency requirements, and mixed fleet flying. 

(c) Indirect Experience. Applicable experience with foreign operators, military 

programs, or other programs that can establish the suitability of training, checking, or currency 

standards may be permitted as a means for FSBs to set MDR or ODR levels. 

(d) Applicant and Industry. FSB provisions are set following solicitation and 

review of comments. 

(3) FSTD Characteristics. Minimum characteristics for FSTDs for training, checking, 

or currency are noted using CFR Part 60 FSTD definitions. When standard criteria for FSTDS 

are not appropriate for an aircraft, the FSB identifies suitable criteria to be applied and 

coordinates with the FAA National Simulator Evaluation Team (NSET). Standard FSTDs 

applicable to each difference level are shown in Figure 7. 
Page 32 

FIGURE 7. STANDARD METHOD and FSTDs 

Difference 

Level 

Difference Level 

Definition Methods FSTD

A Self instruction 

Bulletins 

Manual revisions 

Handout material 

------------------------- 

B Aided instruction 

Slides/video tapes 

Standup instruction 

Computer-based 

training (CBT) 

------------------------- 

C System devices ------------------------- 

FSTDs defined in CFR 

121 attachment 3, 

appendice Q, Table 3B 

D Maneuver devices ------------------------- 

FSTDs defined in CFR 

121 attachment 3, 

appendice Q, Table 3B 

E FFS C/D or aircraft ------------------------- FFS C/D 

Or aircraft 

g. FSB Report Preparation Distribution and FAA Application. 

(1) Report Preparation and Approval. After MDRs are finalized, the FSB report is 

prepared and approved. Sufficient background or explanatory material is provided in the report 

to permit FAA personnel to apply FSB recommendations. The following are elements of an FSB 

report: 

(a) Purpose and Applicability 

(b) Type Rating requirements 

(c) Master Difference Requirements (MDRs) 

(d) Acceptable Operator Difference Requirements (ODR) Tables 

(e) FSB Specifications for Training 
Page 33 

(f) FSB Specifications for Checking 

(g) FSB Specifications for Recency of Experience 

(h) Aircraft Regulatory Compliance Checklist 

(i) FSB Specification for FSTDs 

(j) Applications 

(k) Alternate Means of Compliance 

(l) Regulatory Coordination and Approval 

(m) Board Record 

 

(2) FSB Report Distribution. The FSB report is posted on the OpSpecs Web site for 

implementation in approval of particular operators’ programs. The FAA technical requirements 

described in FSB reports are primarily intended for the operators use to develop programs that 

will be approved by the FAA. 

(3) FSB Report Implementation. FSB recommendations and guidance are provided to 

FAA field offices through FSB reports for each aircraft. These reports are recommendations to 

FAA offices to identify acceptable criteria for modifying flightcrew member training and 

qualification programs under CFR 121.1215. FSB provisions set acceptable standards by which 

FAA inspectors approve, review, correct, or limit individual operator’s programs. The FSB 

report is the basis for approval of modifications of training, checking, and currency programs 

approved by each FAA office. The report is also the basis for pilot certification by FAA or 

operators and the surveillance of operators’ programs. 

h. FSB Report Revision. 

(1) General FSB Revision Process. A general revision process is established to update 

determinations and findings contained in FSB reports. Revisions may be needed annually for 

active fleets with numerous change requests. Revisions may be needed infrequently for aircraft 

not undergoing significant change. 

(2) Revisions for New Aircraft. When an applicant proposes to develop or add a series 

of a type-certificated aircraft, MDRs and other FSB provisions are revised to address that series. 

If an applicant initiates this action, the procedures noted in paragraph 5 regarding initial 

determination of minimum training, checking, currency, and type rating requirements are 

followed. If an operator proposes to add an aircraft that is not covered within an existing FSB 

report (e.g., a foreign manufactured aircraft) POIs should consult with the pertinent Aircraft 

Evaluation Group (AEG). An FSB will determine the best method of addressing the development 

of the necessary FSB report. This is particularly important for older aircraft fleets in which 

differences may be significant, but manufacturer support is no longer available and aircraft 

imported into the United States that have been used only by foreign operators. 
Page 34 

(3) Revision for Aircraft Modified by Operators. When an aircraft is to be modified 

by an operator, the POI determines if the change affects MDRs, example ODRs, or other FSB 

report provisions. The criteria for this assessment includes whether or not the difference affects 

pilot knowledge, skills, or abilities pertinent to flight safety. If a change meets the criteria, the 

operator should supply the POI with a difference description, an analysis of the effects of the 

difference and a proposed training program for the difference. The POI evaluates the proposal 

and if it is acceptable, seeks concurrence from AFS 200. AFS 200 will advise the applicable 

AEG/FSB. The AEG/FSB may concur with the POI’s analysis or propose other action. If FSB 

action is proposed and accepted by AFS 200, the AEG will initiate that action through the FSB 

chairman. The FSB may require that additional information or analysis be provided or that the 

entire test process or parts thereof be applied. The AEG may authorize the POI to approve 

assignment of the difference level. Changes to the MDRs will be made through the normal FSB 

revision process. 

6. OPERATOR’S APPLICATION OF FSB PROVISIONS, PREPARATION, USE, AND 

REVISION OF ODRs. 

a. General. 

(1) Process Overview. FSB reports contain MDRs and other provisions that are applied 

by FAA offices in approving operators’ flightcrew member training and qualification programs 

when operating mixed fleets. MDRs are applied through a particular method that identifies 

specific ODRs and compliance methods. This is necessary so that regardless of which aircraft is 

flown, uniform training, checking, and currency standards are met within the constraints of 14 

CFR Part 121. Paragraph 6 describes operator application of MDRs and other FSB provisions 

for training, checking, and currency. This is done through operator preparation and FAA 

approval of ODRs for each operator. This AC and FSB reports comprehensively address 

differences training, checking, and currency for each aircraft when aircraft are used in mixed 

fleet flying. ODRs are used to identify credits or constraints between related aircraft. The overall 

process for operator application of MDRs and development, approval, use, and revision of ODRs 

is shown in Figure 8. 

(2) Availability and Use of FSB Information. FSB provisions are made available to 

operators through FAA CHDOs, applicants, industry trade associations, posted on the OpSpecs 

Web site, or other sources. When preparing initial or difference programs for specific fleets, 

individual operators apply the requirements of the applicable FSB report. 

b. Application of MDRs and Preparation and Use of ODRs. 

(1) Need for ODRs. When operating a mixed fleet, operators prepare the necessary 

ODR table proposals to describe their particular fleet and show compliance methods. This is 

done to assess effects of differences, plan compliance methods, and obtain POI approval for that 

operator’s specific program. ODR tables must be prepared and approved by the FAA for each 

fleet in which FSB provisions are established. 

(2) Operator Responsibilities. The operator’s responsibilities include: 

(a) Specification of a base aircraft. 
Page 35 

(b) Identification of differences between the aircraft within a mixed fleet. 

(c) Preparation of proposed ODR tables. 

(d) Assessment and description of the effects of the differences on training, 

checking, and currency. 

(e) Proposal of training, checking, and currency methods consistent with MDRs 

and FSB provisions. 

(f) Presentation of proposed ODR tables with necessary supporting information to 

the FAA POI for approval. 

(g) Revision of ODR tables when aircraft are introduced, modified, phased out, 

devices change, or MDRs change. 

(3) Use of Standard ODR Format. A common format for ODR tables is used to 

facilitate preparation, review, use, comparison with MDRs, and ensure consistency of application 

and approval by POIs. The common format is used in all cases where ODR tables are required 

except when only a few minor differences exist and level A applies. In this event, letters between 

an operator and FAA containing the necessary information and approval may suffice if 

acceptable to the POI. 

(4) Minimum Threshold for ODR Preparation. Within the mixed fleet, a minimum 

threshold for preparation of ODR tables occurs when there are differences that potentially affect 

knowledge, skills, or abilities necessary for flight safety. Differences not related to this criterion

need not be addressed in ODR tables. 

(5) ODR Description and Examples. ODRs are described in paragraph 4. Examples of 

acceptable ODR tables for a particular type-certificated aircraft are shown in each FSB report. 

(a) Systems Shown on the ODR Table of Figure 3. An example of several pages 

from an ODR table is shown in Figure 3. Figure 3 shows the application of ODRs to address 

systems differences and compliance methods. In Figure 3 differences are grouped in the order 

associated with a typical operations manual. Air Transport Association (ATA) code numbers are 

shown for cross-reference. The “Remarks” column depicts differences and the “Flight 

Characteristics” and “Procedural Change” columns address effects of differences. 

(b) Maneuvers Shown on the ODR Table of Figure 3. The “Remarks” column 

depicts differences. The “Flight Characteristics” and “Procedural Change” columns address 

effects of differences. The reference “SEE APP” refers you to an appendix to the table, which the 

operator prepares to more fully list and explain the particular procedural changes that pertain to 

the maneuver in the “Procedural Change” column. 

c. Selecting Base Aircraft. An operator chooses a base aircraft from one of the aircraft 

operated. Base aircraft are defined in Appendix 1. Additional information regarding base aircraft 

selection is in paragraph 7. 
Page 36 

d. Identification of Differences and the Analysis of Effects of Those Differences. 

Differences must be described between base aircraft and other related aircraft. This may be done 

from base to each other related aircraft. Differences may also be described from any related 

aircraft to each other related aircraft. As long as a complete and clear relationship can be drawn 

from the base aircraft to each other related aircraft and all MDR requirements are met from the 

base aircraft, to each other related aircraft, there is no need to describe each possible combination 

of aircraft. This permits a comprehensive identification of differences that exist in the fleet, 

determines the effects of those differences, and shows compliance methods. Differences are 

generally organized to follow an operations manual or flight manual to facilitate use and review, 

and should be categorized by design, systems, and maneuvers. Effects of differences are stated in 

terms of effects on flight characteristics and procedures. Procedures include normal, nonnormal, 

alternate, and recall procedures, as applicable. Since complete descriptions may be to lengthy for 

direct incorporation in ODR tables, appendices, or references to other operator’s documents may 

be used to describe differences or effects. Some differences or effects may be repeated in the 

analysis. For example, an FMS difference may be noted in both a navigation system section and 

maneuver section associated with preflight setup. The objective is to assure each difference that 

pertains to pilot training, checking, or currency is identified and addressed, so it is not necessary 

to limit difference descriptions to prevent overlap. 

e. Identification of Compliance Methods. Once differences and difference effects are 

described, methods of comprehensively addressing each difference (compliance methods) are 

shown. With the difference descriptions, redundancy may occur. The same training or checking 

compliance item shown for one item may also be associated with and credited for other items. 

The objective for description of compliance methods is to show that each difference is addressed 

in some appropriate way, to show that the method and level chosen is consistent with the FSB 

MDRs, and example ODRs at a level at least equal to that required by the MDRs. 

f. When Proposed ODR Compliance Methods Do Not Meet MDRs. If proposed ODR 

compliance methods do not satisfy MDRs or other FSB report constraints, the following 

alternatives exist: 

(1) Differences may be reduced or eliminated by modification of aircraft, systems, or 

procedures. 

(2) Other training methods or devices that fully comply with MDRs and other FSB 

provisions may be acquired, leased, or otherwise applied. 

(3) Pilot assignments may be separated for a fleet so that mixed flying of related aircraft 

does not occur. 

(4) MDR change proposals may be requested through FAA POIs to the FSB. If FSB 

authorized changes to the MDRs are made, the operator may then apply the revised criteria. 

g. Application, Review and Approval. Paragraph 7 describes the FAA review and 

approval process. The process is summarized here to facilitate ODR table preparation. An 

operator submits the proposed ODR tables and necessary supporting information to the POI to 

apply for differences program approval. The supporting information may include any appendices 
Page 37 

to the ODR tables necessary for evaluation of the proposal, a transition plan if needed, and a 

proposed schedule for implementation. POIs may also require review of such pertinent and 

additional information as copies of bulletins, manuals, or other training materials, before they 

approve proposed ODRs. If devices are proposed that are not approved by the POI, or evaluated 

by the NSET, a review and approval of those training devices may be necessary before ODR 

approval. Sufficient lead-time must be provided to the FAA for review. Lead-time depends on 

such factors as the complexity of program, proposed difference levels, number of related aircraft, 

other operator precedents already set, and FAA experience with the proposed aircraft, training 

devices, and methods. Many noncontroversial level A changes can be reviewed and approved in 

a few days. Complex programs with many related aircraft can require months for review and 

approval. It is the operator’s responsibility to consult with the POI to ensure that sufficient leadtime is provided to review initial submissions or changes. At least 60 days notice is acceptable 

for most programs. After the operator submits the program proposal, POIs compare the proposed 

ODR with the FSB report provisions including the MDRs. POIs consult pertinent FAA policy 

directives (Handbook, notices, Safety Alerts for Operators (SAFO), etc.) for interpretations or 

guidance in accomplishing the review. In certain instances the POI should consult with the FSB 

before ODR approval. If ODRs are consistent with FAA policies and within the constraints of 

the MDRs and example ODRs, the POI will approve the operator’s ODR tables and its proposed 

differences program. When approved by the FAA, ODRs establish the basis for training, 

checking, and currency programs for a given fleet for that operator. 

h. Transition Period for ODR Implementation. In certain instances, a transitional period, 

agreed upon by the POI with FSB concurrence, may be necessary to permit operators to continue 

operations under previously approved programs until they are able to comply with POI-approved 

FSB provisions. This is necessary when these provisions are initially set or revised and they 

require lead-time for program preparation, device acquisition, or to revise previously approved 

programs. Paragraph 7m and the individual FSB reports for each type-certificated aircraft discuss 

FAA approval of transition provisions. 

i. ODR Revision. ODR revisions are initiated when changes occur in an operator’s fleet 

relating to differences, difference effects, or compliance methods. ODR revisions are appropriate 

when such changes affect pilot knowledge, skills, or abilities relevant to flight safety. Examples 

of program changes or factors that may require ODR revision include: 

(1) Addition or deletion of aircraft in a fleet; 

(2) Modification of base aircraft or comparison aircraft in a fleet; 

(3) Change of base aircraft; 

(4) Discontinuation of use, addition of new or modification of training devices 

referenced by ODRs; 

(5) Revision of training methods with a resulting change in compliance levels; 

(6) Changes in effects of differences such as revised procedures, performance, or flight 

characteristics; 
Page 38 

(7) FAA revision of MDRs or other FSB provisions; 

(8) Adverse OE or training and checking experience that dictates inadequacy of ODRs, 

MDRs, or other FSB provisions; 

(9) FAA surveillance results, enforcement actions, or failure of an operator to comply 

with provisions of their approved ODRs; and 

(10) Other factors as determined by the POI. 

NOTE: Revisions to ODRs are approved using the same procedures as for 

initial ODRs approval. 
Page 39 

 

FIGURE. 8 

FSB PROCESS

ORDER 8900.1 

OTHER REQUIREMENTS 

MDR TABLE 

POI REVIEW 

& 

AFS 200 

CONCURRENCE 

FSB 

REPORT 

FAA 

APPROVED 

ODR 

TABLE(S) 

OPERATIONS 

PROPOSED 

ODR TABLE(S) 

(FROM OPERATOR) 

FSB CHDO 

MDR ODR REVISIONS 

REVISION 

REQUESTS (IF 

NEEDED) 

APPROVAL OF TRAINING 

PROGRAM(S) CHECK 

AIRMEN OPS-SPECS ETC. 

MDR-Master Difference Requirements 

ODR-Operator Difference Requirements 

POI-Principal Operations Inspector 

FSB-FAA Flight Standards Board 

OPSPECS-Operations Specifications 
Page 40 

7. FAA REVIEW AND APPROVAL OF OPERATOR PROGRAMS. 

a. General. 

(1) FAA Responsibilities. FAA has the responsibility for review, approval, and 

continuing surveillance of individual operator programs consistent with this AC and FSB 

recommendatons. Within a CHDO or FSDO, POIs have the responsibility for program review 

and approval. In addition to review, approval, and continuing surveillance of operator programs, 

CHDO and other district offices manage pilot certification consistent with the criteria of this 

AC and FSB recommendations. 

b. Operator Application of ODRs. 

(1) Operators Using Related Aircraft in Mixed fleet Flying. If FSB provisions are 

published, operators operating aircraft in mixed fleet flying IAW CFR Part 121 may apply 

recommendations of this AC and the FSB report. 

(2) Threshold Requiring ODR Preparation. Even though an operator has different 

configurations of aircraft used in mixed fleet flying, there is some threshold below which ODR 

tables and POI approval is not required. The threshold requiring AC and ODR application occurs 

when differences in related aircraft affect pilot knowledge, skills, and/or abilities pertinent to 

flight safety. If systems, controls, indications, procedures, or maneuvers are different and these 

differences have an effect that significantly relates to what the pilots needs to know or do for safe 

mixed fleet flight operation, then an operator should prepare ODR tables and must seek FAA 

approval. Conversely, ODR tables would not need to be prepared in situations that do not affect 

flight safety. In such instances ODR tables are not needed even though pilots routinely operate 

several related aircraft. A minimum threshold is set to preclude unnecessary administrative 

assessment of mixed fleet flying, which has no safety implications. If changes to the fleet do not 

affect pilot knowledge, skills, or abilities affecting flight safety, then such changes need not be 

considered in addressing FSB provisions or this AC.

(3) FAA Review of ODR Proposals. After preparation the carrier submits proposed 

ODR tables and supporting information to the CHDO and POI for review and approval. POIs 

evaluate the following: 

(a) The operator has made an appropriate identification of a base aircraft. 

(b) Operators have comprehensively identified differences in the particular fleet. 

This includes appropriate ODR table comparisons between the base aircraft and each related 

aircraft. 

(c) The operator’s assessment of the affects of differences on flight characteristics 

and procedures for the base aircraft and each related aircraft are suitable and valid. 

(d) The compliance methods listed are consistent with the requirements of the MDR 

tables, footnotes, other pertinent FSB report provisions, FAA Order 8900.1, and associated 

advisory materials. 
Page 41 

(e) ODR provisions adequately address any “subtle differences” between related 

aircraft that have a possibility of inducing potentially serious pilot errors. 

(f) Training materials, methods, devices, and FSTDs proposed are acceptable, 

approved by the NSET if necessary, or if FSB provisions are applied, the ODR tables meet FSB 

constraints. 

(g) ASIs, APMs, and APDs are prepared to apply FSB report checking standards. 

(h) Implementation plans are adequate and consistent with FSB recommendations 

and other FAA policy. 

(i) Other factors determined necessary by the POI are considered and any 

requirements met. 

(4) Example ODR tables and MDRs. The POI uses the example ODR tables and the 

MDRs provided in the FSB report as a basis for evaluating the suitability of a particular 

operator’s proposed ODR table. The MDR always remains the primary basis for comparison. 

The AEG should be consulted in the absence of conclusive guidance in making such judgments. 

Guidance for evaluation of specific system or maneuver items may be found by comparison of 

the proposal with the example ODR table shown in the FSB report and other approved ODR 

tables. The operator may use devices, techniques, or methods of an equal or higher difference 

level. Critical methods should be at least at the level specified by the FSB on the MDRs and 

shown in the example ODR table. Actual ODR tables proposed by the operator may show a 

variety of compliance methods to satisfy a particular item, ranging from level A through the 

level required by the MDRs. For example, if the MDR requirement is a minimum of level C, the 

operator may propose to use a combination of level A bulletins, level B slide tape presentations, 

and level C training devices to satisfy pertinent items. However, at least level C should be shown 

for critical items. The operator may choose to satisfy a level C MDR provision with level D or 

level E methods. 

(5) ODR Review Example. The following is an example of the process for review of a 

specific item on a proposed ODR table. For each proposed ODR item both the FSB example 

ODR table and MDRs are consulted and compared with the operator’s proposal. If the MDRs 

specify that level C devices are needed for training, checking, and currency between the base 

aircraft and a related aircraft and the example ODR table shows applicable level C systems 

differences or maneuvers, then the POI should ensure that the proposed ODR table submitted 

also shows at least level C for those pertinent systems or maneuvers. 

c. Base and Other Aircraft Identification. 

(1) Selecting the Base Aircraft. Base aircraft are defined in Appendix 1. In general, 

base aircraft are used as reference for comparison of differences that affect, or could affect, pilot 

knowledge, skills, or abilities pertinent to flight safety. A base aircraft should typically be the 

aircraft that the operator trains to first, the aircraft that the operator has the largest number of, the 

aircraft most pilots fly frequently, or the aircraft that represents a configuration that the operator

eventually will have as a standard. Another aircraft may be selected as a base aircraft when the 

previous base aircraft is being phased out, converted to a new configuration, or other such 
Page 42 

factors. A base aircraft may be redesignated at the discretion of the operator with FAA 

concurrence. A base aircraft is identified by make, type-certificated aircraft, model, and series or 

other distinguishing classifications. Classification should distinguish pertinent differences in 

configuration, handling characteristics, performance, procedures, limitations, controls, 

instruments, indicators, systems, installed equipment, options, or modifications. 

(2) Identifying Related Aircraft. A related aircraft is an aircraft or a group of aircraft 

with the same characteristics that have pertinent differences from a base aircraft. Pertinent 

differences are those that require different or additional pilot knowledge, skills, and/or abilities 

that affect flight safety. Differences considered pertinent are those relating to configuration, 

handling characteristics, performance, procedures, limitations, controls, instruments, indicators, 

systems, installed equipment, options, or modifications. Related aircraft can exist between 

different models, series or within a model/series. When designated in FSB reports, any aircraft 

included in a MDR table is considered a related aircraft. Like base aircraft, operators designate 

related aircraft by one of the following: 

• Model/series. 

• FAA registration “N number”. 

• Operator tail number. 

• Any other classification that can uniquely distinguish pertinent differences 

between each related aircraft group and a base aircraft. 

(3) Accounting for Each Related Aircraft. The important factor in base and related 

aircraft identification and ODR table preparation is that regardless of the combination used, there 

should be direct and complete traceability of both differences and compliance methods. There 

must be a clear description showing the adequacy of compliance methods to assure proper 

training, checking, and currency to safely operate each aircraft assigned. 

d. Approval of ODRs. 

(1) Approval Method. Following review and determination that an operator’s program 

addresses the FSB recommendations, the POI, with concurrence from AFS 200, approves that 

particular program by signing ODRs. ODR tables are approved for each applicable related 

aircraft. Signature of ODRs or revisions, together with other relevant documents such as training 

programs and OpSpecs, constitute approval by the POI of that operator’s differences training, 

checking, and currency program requirements. ODR tables are used for most programs. In 

instances where aircraft have only a few minor differences at level A, approval may take the 

form of a letter including necessary information in lieu of using tables. 

e. FSB Revision of MDRs or Other FSB Provisions. When requested, the FSB reviews an 

operator’s proposals and if necessary modifies MDRs and other FSB provisions. Major changes 

in the MDR table may require review by the full FSB. The FSB may consider minor changes or 

interpretations on an ad hoc basis between FSB meetings for that aircraft. For some requests 

changes can be made based on existing or the supplied information. Complex cases may require 
Page 43 

testing to be conducted by the applicant before the MDR table is changed. Should the MDRs be 

updated to accommodate a change request, the proposed ODR can be approved within the new 

MDRs. 

f. Proving Tests. When a related aircraft with difference levels C or greater is introduced 

by an applicant, proving runs may be needed. Proving runs are usually needed for levels D and 

E. At level E, regulatory provisions for proving runs must be met. Training flights, test flights, 

delivery flights, and demonstration flights may be credited toward levels C and D proving 

requirements if necessary operational experiences are demonstrated and the flights are IAW an 

FAA-approved plan. FAA Order 8900.1 describes policies for FAA approval of proving tests. 

g. Line-Oriented Flight Training (LOFT) or SLF. When operators have LOFT or SLF 

programs and additional related aircraft are approved, the POI should review those LOFT or SLF 

programs to assure applicability to each related aircraft. SLF in the aircraft, or in some instances 

FFS (as determined by the FSB), may be necessary IAW recommendations of the FSB report and 

with the approval of the POI. 

h. OE. As described in this AC and FSB reports, OE is consistent with definitions and 

requirements of 14 CFR Part 121. OE credit, as provided by the FSB for experience with related 

aircraft, may be permitted with the approval of the POI. 

i. Limitations on the Total Number of Related Aircraft. 

(1) Mixed Flying of Multiple Related Aircraft. When mixed fleet flying involves 

pilots operating more than a base aircraft and a single additional related aircraft, additional 

constraints limiting the total number of aircraft may apply. When more than two related aircraft 

are flown, POIs should specifically ensure that subtle or compounded differences between the 

various related aircraft do not result in confusion of procedures, maneuvers, or limitations. ODRs 

proposed for the overall combination of aircraft to be flown should be examined to ensure the 

following: 

(a) That multiple differences do not result in confusion of requirements or an 

excessive level of complexity for pilots to adjust to or retain important differences information; 

(b) That subtle variations in differences information are not mistakenly applied and 

lead to unsafe conditions; and 

(c) That the amount of differences information is not excessive, not applied to the 

wrong aircraft, or not forgotten. 

j. Compliance Checklist for CHDOs. FSB reports provide a regulatory compliance 

checklist. The checklist identifies those 14 CFR Part 121, ACs, or other FAA requirements that 

are in compliance. 14 CFR Part 121 items not shown on the checklist or items shown but not 

reviewed by the AEG/FSB for compliance should be reviewed by the CHDO before POI 

approval of OpSpecs permitting those aircraft to be used under 14 CFR Part 121. Items found not 

compliant by the AEG/FSB should be reconciled and compliance established before operation. 

The compliance checklist is an aid to CHDOs used to show the status of those 14 CFR Part 121 

items evaluated by the AEG/FSB, but does not comprehensively address all possible 14 CFR 
Page 44 

Part 121 items and ACs that an operator may need to demonstrate compliance. OpSpecs, 

exemptions, deviations, or other factors, which the AEG/FSB may not be aware of, may also 

apply and may modify compliance status or methods shown in the checklist. 

k. Aircraft That Do Not Have an FSB Report. When an FSB report is not prepared for a 

given type-certificated aircraft, or when MDRs or other recommendations are not shown, 

programs are approved IAW the 14 CFR Part 121, Order 8900.1, and other pertinent inspector 

guidance material. 

8. APPLICATION OF REQUIREMENTS TO AIRMEN CERTIFICATION. 

a. General. In addition to master requirements, the FSB report contains specifications for 

administration of proficiency checks by FAA inspectors or operator check airmen. FAA pilot 

certification inspectors, APMs, operator check airmen, APDs, and DPEs should be familiar with 

FSB provisions regarding the proper administration of any necessary checks or evaluations for 

type-certificated aircraft or their series covered by the FSB report. 

b. Checks Regarding Complex Systems. 

(1) Partial proficiency checking is required for differences associated with systems that 

are determined to be at or greater than level C. 

(2) Complex systems checks include hands-on operation and ensure demonstrated 

procedural proficiency in each applicable mode or function. Specific items and flight phases to 

be checked are specified (e.g., initialization, takeoff, departure, cruise, arrival, approach, and 

pertinent nonnormals). 

NOTE: The FSB may recommend additional training beyond that which is 

otherwise required by 14 CFR Part 121 to qualify in each type certificated 

aircraft. 

9. FSTD APPROVAL. 

a. NSP Representation to the FSB. An NSP member may serve as an advisor to the FSB or 

a member of the FSB, to address designation of and approval processes for FSTDs. 

(1) Coordination of NSP Criteria with the FSB. National simulator team development 

of criteria for training devices and approval test guides for new aircraft are coordinated with the 

FSB. This ensures compatibility of FSB/NSP requirements and effective use of resources for 

development of approval test guides and determination of FSB provisions. 

NOTE: FSTDs are approved for operator use IAW 14 CFR 121.1345 and QPS 

Appendix 3 Table 3B.

10. REVIEW AND APPROVAL. FSB reports are approved as designated by AFS-1. In the 

event that revision of an FSB report is necessary, the FSB is provided with necessary policy 

guidance to implement applicable changes. 
Page 45 

11. APPEAL OF FAA DECISIONS. When there is disagreement with provisions of an FSB 

report, that disagreement may be expressed to the FSB chairman for the pertinent typecertificated aircraft. If an issue cannot be resolved, the issue may then be addressed to AFS-200. 

Additional information, data, or analysis may be provided to support differing views regarding 

the FSB provisions in question. 

MM/DD/YY DRAFT AC 120-53B 

 Appendix 3 

Page 1 

APPENDIX 3. RATINGS AND LEVEL TESTS-PLANNING AND APPLICATION 

TABLE OF CONTENTS 

1. PREPARATION........................................................................................................................3 

2. TYPE RATING DETERMINATION THROUGH ANALYSIS-LEVEL A OR B TRAINING 

ONLY ........................................................................................................................................4 

3. FUNCTION EQUIVALENCE-LEVEL A OR B TEST 1 (T1) 

a. Test Purpose.........................................................................................................................5 

b. Test Subjects ........................................................................................................................5 

c. Test Process .........................................................................................................................5 

d. Safety Pilot...........................................................................................................................5 

e. Successful Test.....................................................................................................................6 

f. Failure of Test......................................................................................................................6 

4. HANDLING QUALITIES COMPARISON BETWEEN AIRCRAFT-TEST 2 (T2) 

a. Test Purpose.........................................................................................................................6 

b. Test Subjects ........................................................................................................................6 

c. Test Process .........................................................................................................................6 

d. Safety Pilot...........................................................................................................................7 

e. Successful Test.....................................................................................................................7 

f. Failure of Test......................................................................................................................7 

5. SYSTEM DIFFERENCES TEST AND VALIDATION OF TRAINING AND 

CHECKING-TEST 3 (T3) 

a. Test Purpose.........................................................................................................................7 

b. Test Subjects ........................................................................................................................7 

c. Test Process .........................................................................................................................8 

d. Successful Test.....................................................................................................................8 

e. Failure of Test......................................................................................................................8 

6. CURRENCY VALIDATION-TEST 4 (T4) 

a. Test Purpose.........................................................................................................................9 

b. Test Subjects ........................................................................................................................9 

c. Test Process .........................................................................................................................9 

d. Successful Test.....................................................................................................................9 

e. Failure of Test......................................................................................................................9 

7. INITIAL OR TRANSITION TRAINING/CHECKING PROGRAM VALIDATIONTEST 5 (T5) 

a. Test Purpose.......................................................................................................................10 

b. Test Subjects ......................................................................................................................10 

c. Test Process .......................................................................................................................10 

d. Successful Test...................................................................................................................10 

e. Failure of Test....................................................................................................................10 
AC 120-53B DRAFT MM/DD/YY 

Appendix 3 

Page 2 

8. COMMON TAKEOFF AND LANDING CREDIT (CTLC)-TEST 6 (T6) 

a. Test Purpose.......................................................................................................................10 

b. Test Subjects ......................................................................................................................11 

c. Test Process .......................................................................................................................11 

d. Successful Test...................................................................................................................11 

e. Failure of Test....................................................................................................................11 
MM/DD/YY DRAFT AC 120-53B 

 Appendix 3 

Page 3 

APPENDIX 3. RATING AND LEVEL TESTS—PLANNING AND APPLICATION 

1. PREPARATION. 

a. The type rating, difference level definition, and test process are initiated when an 

applicant presents an aircraft for type certification. If the applicant presents a candidate aircraft 

to the Flight Standardization Board (FSB) as a new aircraft type certification with no anticipated 

application for type rating credit for similarities with aircraft previously type certificated, then 

the FSB analyzes the training program requirements using test T5. The results of T5 will 

determine a separate type rating and the minimum required training, checking, and currency 

standards as applicable to that type-certificated aircraft. If the applicant presents an aircraft 

seeking pilot training, checking, or currency credit, based on similarities with an aircraft 

previously type certificated, a series of possible tests (T1/T2/T3) are developed and used to 

determine its level of difference with the base aircraft of comparison. The results of these tests 

will determine the minimum required training, checking, and currency standards as applicable to 

the candidate aircraft. T6 comparisons may permit Common Takeoff and Landing Credit 

(CTLC) between different type-certificated aircraft. In Appendix 2 the details of these situations 

provide further amplification. 

b. To begin the evaluation process, the applicant identifies candidate aircraft. The aircraft 

are then assigned to logical aircraft groups to be described in Master Difference Requirements 

(MDR) tables and the FSB report. 

c. The applicant identifies major differences pertinent to the aircraft and makes comparisons 

with the proposed candidate aircraft. A differences document (i.e., an appropriate sample 

Operator Difference Requirement (ODR) table) summarizes the identified differences. Since 

combinations of related aircraft may be numerous and only typical differences are needed at this 

stage for test definition, the applicant may select representative ODRs for preparation. 

d. Based on the above analysis (including preliminary flight test results or flight simulation 

estimates, if available), the applicant proposes difference levels to be specified in each cell of the

MDR table for the various aircraft combinations. 

e. The applicant proposes applicable elements of the test process (T1 through T5 and T6 for 

CTLC) and a plan for validation of the intended difference levels. Specific aircraft, times, 

devices, etc. are identified to conduct the required tests for the candidate aircraft. Included in the

proposal are any necessary interpretations of expected results using established standards. Any 

special, unique, or additional definitions of successful outcomes are also identified. 

f. The scope of T1 through T6 is keyed to basic visual flight rules (VFR) and instrument 

flight rules (IFR) operations in the National Airspace System (NAS). 

g. FAA/applicant agreement is reached on the grouping of aircraft, proposed tests, test 

plans, schedules, subjects, and interpretation of possible outcomes. 

h. Subject qualifications are addressed at the time of test specification when test agreement 

is reached with the applicant. Test subjects for all tests except T6 are drawn from the FAA. 

Subject selection considers the factors such as the following: 
AC 120-53B DRAFT MM/DD/YY 

Appendix 3 

Page 4 

(1) Needed background skills of candidates (previously qualified aircraft); 

(2) General flight experience and currency; 

(3) Test requirements such as location, short notice access, and skills needed for 

subjects; 

(4) Technical areas, qualifications, or experience that subjects should not have to avoid 

test prejudice; 

(5) Eventual FAA geographic or operator related distribution requirements for ASI, 

APM, and POI personnel; and 

(6) Other special experience as needed for a particular program. 

i. During preparation for testing and evaluation of results, appropriate Aircraft Certification 

Flight Test Branch coordination is accomplished so that flight characteristic issues and, in 

particular, special flight characteristics can be suitably identified and addressed. 

NOTE: Tests T1 and T2 must be conducted in the candidate aircraft for the 

determination of training, checking, and currency requirements. A FFS may 

be used for FSB selected T-tests that involve partial task evaluation of 

systems or components, which do not directly relate to aircraft handling 

qualities or core pilot skills. These types of tests would normally require only 

a training device with no visual or motion capabilities. The FSB chairman 

may elect to use a FSS before its qualification by the National Simulator 

Program (NSP). 

2. TYPE RATING DETERMINATION THROUGH ANALYSIS-LEVEL A OR B 

TRAINING ONLY. 

a. Typically, with the introduction of a new aircraft, or when training credit is sought in a 

comparison of a base and candidate aircraft, the T1 through T5 testing process determines type 

rating. Not all changes or modifications to an aircraft or on occasion, the certification of a related

aircraft may require flight-testing to assess their impact upon type rating. Type rating 

determination through analysis may be considered if the changes do not influence aircraft 

handling, introduce no significant change to systems operation or pilot procedures, and can be 

addressed at level A or B training. 

b. The analysis process can be used if the aircraft handling has not changed significantly. In 

most cases, it should be obvious that the change will not affect aircraft handling but if additional 

data is needed to make the determination, the information can be obtained from the assigned 

FAA Aircraft Certification Service (AIR) or through the applicant’s flight test data. Following is 

a list of typical changes evaluated through the analysis process: 

(1) Maximum operating weights (revised aircraft type certificate data sheet (TCDS)). 
MM/DD/YY DRAFT AC 120-53B 

 Appendix 3 

Page 5 

(2) An engine type or thrust change that does not require significant design changes to 

aircraft flight controls. 

(3) Maximum passenger capacity (revised aircraft TCDS).

(4) Avionic upgrades (Supplemental Type Certificate (STC) or manufacturer production 

line upgrade). 

(5) Proven electronic flight bag installation, (STC or manufacturer production line 

upgrade). 

(6) Passenger to cargo conversions or Freighter variation of passenger aircraft. 

c. When the analysis process is completed, it is recorded as a revision to the training 

courseware and to the existing FSB report for the base and/or candidate aircraft 

3. FUNCTIONAL EQUIVALENCE-LEVEL A OR B TEST 1 (T1). 

a. Test Purpose. The T1 test is conducted to determine if training level A or B is 

appropriate between the base and candidate aircraft. 

NOTE: If the applicant communicates that the training, checking and 

currency requirements for the candidate aircraft may exceed level B, the T1 

test can be waived and the evaluation process then moves directly to the T2 

test. By waiving the T1, the applicant acknowledges that differences exist 

between the base and candidate aircraft, and may demand that training, 

checking, and/or currency requirements up to but not exceeding level D are 

applied. 

b. Test Subjects. Test subjects are designated FAA FSB members, trained, experienced, 

and current on the base aircraft with no differences training for the candidate aircraft. The 

applicant may provide proficiency training to the designated FSB members before testing begins. 

c. Test Process. The applicant initiates the test process when they propose that the 

minimum training, checking, and currency requirements for the base and candidate aircraft are 

no greater than level B differences. T1 is typically conducted using one group of test subjects. 

Subjects will initially be given a “no jeopardy” flight check for their base aircraft to calibrate 

performance before taking the pertinent flight check in the candidate aircraft being evaluated. 

The flight check undertaken in the candidate aircraft will address the differences between the 

base aircraft and candidate aircraft. The test may be administered or observed by more than one 

FSB member to ensure consistency and uniformity of test procedures and common 

understanding of subject performance and outcomes. 

d. Safety Pilot. A “safety pilot,” serving as PIC in the aircraft and functioning as pilot 

monitoring in either seat, will intervene to prevent damage to the aircraft or to limit maneuvers 

that endanger safety of flight. 
AC 120-53B DRAFT MM/DD/YY 

Appendix 3 

Page 6 

e. Successful Test. FSB members decide the outcome of the T1 test consistent with 

previously agreed upon criteria. The FSB determines the areas of differences training required 

and specifies necessary devices or training limitations. If the T1 test is passed, the pertinent 

aircraft pairs are assigned to level A or level B training differences. Successful completion of T1 

results in the designation of a type rating that is either the “same” as, or is “common” to the 

base aircraft. 

f. Failure of Test. If the T1 test is failed and retesting is not considered, level A or B 

cannot be assigned. This generally requires completion of T2 and T3. If requesting training 

credit, the applicant may ask for and receive credit for those items passed in T1. T1 retesting 

may be considered at the discretion of the FSB. 

4. HANDLING QUALITIES COMPARISON BETWEEN AIRCRAFT-TEST 2 (T2). 

a. Test Purpose. The T2 test compares handling qualities between the base and candidate 

aircraft. At the discretion of the FSB chairman the T2 test may be completed through analysis, 

without requiring an aircraft flight. Determining if the analysis process can be used requires 

verification that the aircraft handling has not changed significantly as described in the “test 

process”. In most cases, it should be obvious that the change will not affect aircraft handling but 

if the determination requires additional data, the information is obtained from the assigned FAA 

Aircraft Certification Office or through the applicant’s flight test data. With FAA agreement, 

elements of T2 may be incorporated within the T3 test to verify that an advanced FFS or aircraft 

training is not needed to address handling qualities. 

NOTE: If T2 is conducted on an aircraft that is expected to require a 

separate type rating with CTLC, credit will be validated by using the T6 

process. 

b. Test Subjects. Test subjects are designated FAA FSB members, who are trained, 

experienced and current on the base aircraft with no differences training for the candidate 

aircraft. Training to proficiency may be provided to the designated FSB members by the 

applicant before the start of testing. 

c. Test Process. The applicant initiates the test process when they analyze available flight 

or simulation test data, and aircraft design or system differences, and determine that handling 

similarities exist between the base and candidate aircraft. From this determination the applicant 

makes their T2 proposal. Before the test, representatives of the FSB review the T2 test profile to 

ensure that critical handling quality aspects of the candidate aircraft are examined. The flight 

evaluation consists of relevant parts of a proficiency check as determined by the FSB chairman. 

T2 consists of a comparison between selected pilot certification flight check maneuvers (normal 

and nonnormal) administered first in the base aircraft (using either the actual aircraft or a level C 

or D FFS then in the candidate aircraft. Although T2 testing should always be accomplished in 

the candidate aircraft, some portions that significantly affect aircraft safety, such as flight control 

failures, may be conducted in a FFS suitable for the test. Subject pilots are evaluated on 

performance of required maneuvers consistent with standards set by 14 CFR Part 121 and an 

assessment of the degree of difficulty in performing maneuvers in the candidate aircraft 

compared to the base aircraft. The test may be administered or observed by more than one FSB 
MM/DD/YY DRAFT AC 120-53B 

 Appendix 3 

Page 7 

member to ensure consistency and uniformity of test procedures and common understanding of 

subject performance and outcomes. 

d. Safety Pilot. The safety pilot serving as PIC in the aircraft and functioning as pilot 

monitoring in either seat, will intervene to prevent damage to the aircraft or to limit maneuvers 

which endanger safety of flight. The safety pilot can only assist the subject pilot in areas 

unrelated to the handling qualities determination. For example, the safety pilot can remove 

impediments to progression of the test but cannot fly, coach, or train the subject on any aspect of 

the test related to handling, vision cues, or motion cues. The safety pilot may not actuate primary 

flight controls during the evaluation, or instruct, lead, or coach test subjects in any manner. The 

safety pilot may: 

(1) Perform all routine pilot monitoring duties. 

(2) Set up or adjust systems including those normally operated by the pilot flying in 

accordance with pretest agreements. 

(3) Address or resolve procedural impediments. 

(4) Manage and satisfy checklists. 

(5) Make normal call outs. 

e. Successful Test. The FSB members decide T2 test outcome consistent with previously 

agreed upon criteria. Acceptable pilot performance in completion of designated maneuvers, 

without differences training, establishes that the candidate and base aircraft are sufficiently alike 

in handling characteristics to permit assignment of level B, C, or D. The test process can then 

advance to differences training and the T3 test. 

f. Failure of Test. Failure of T2 means that major handling differences exist during critical 

phases of flight or that numerous less critical differences were identified that warrant training in 

a FFS or aircraft. Accordingly, level E differences will be assigned and the FAA will issue a 

separate type rating. With a T2 failure, the next step in the testing process is T5 to validate 

level E requirements and the proposed training course. Failure of the T2 does not necessarily 

mean that the base and candidate aircraft do not share a high degree of system and/or handling 

commonality. The applicant may elect to use the data collected during the T2 process to justify 

approval of a shortened type rating course for pilots that are trained on the base aircraft and are 

transitioning to the candidate. 

5. SYSTEM DIFFERENCES TEST AND VALIDATION OF TRAINING AND 

CHECKING- TEST 3 (T3). 

a. Test Purpose. Test 3 is used to evaluate the proposed differences training, checking, and 

training devices at levels B, C, or D. 

b. Test Subjects. Test subjects are designated FAA FSB members, trained, experienced, 

and current on the base aircraft and have completed the applicant’s proposed differences training 
AC 120-53B DRAFT MM/DD/YY 

Appendix 3 

Page 8 

in the candidate aircraft. Training to proficiency may be provided to the designated FSB 

members by the applicant before the start of testing. 

c. Test Process. T3 is a system differences test and a validation of training and checking. It 

is used when the equivalent handling test (T2) is successfully completed or when T2 is being 

incorporated as part of T3. T3 is administered in two phases following differences training of a 

pilot in the candidate aircraft. 

(1) First Phase. The successful completion of a pilot certification flight check to assess 

pilot knowledge, skills, and abilities pertinent to operation of the aircraft being tested. If a full 

check is proposed, the tests are similar to those used for T1 as described in paragraph 2 above. If 

a partial check is used, the process is similar, but the FSB determines the test items based on the 

applicant’s proposals. The first phase will include either a proficiency check as defined by 

14 CFR Part 121 , partial proficiency check, or individual aircraft system operation check 

administered to pilots in the FSS or candidate aircraft. The check is administered assuming 

currency in the base aircraft and completion of the proposed training in the candidate aircraft. 

(2) Second Phase. Line oriented flying (LOF) following completion of the flight check. 

The LOF phase of the test is used to validate the training and checking being proposed, fully 

assess particular difference areas, examine implications of mixed fleet flying, assess special 

circumstances such as minimum equipment list (MEL) effects, and identify the effects of pilot 

errors potentially related to the differences. The test is done in a real line flight environment that

includes typical weather, routes, airports, air traffic control (ATC), and other factors that are 

characteristic of those in which that aircraft will be operated. LOF tests may be conducted in test 

aircraft, FSS, or with a combination of these in conjunction with function and reliability 

certification tests. The LOF portion of the test may be used to evaluate complex issues or issues 

that cannot be fully detailed in a brief flight check since a check only samples pilot knowledge 

and skills in a limited and highly structured environment. LOF is an integral part of T3 and must 

be successfully completed before “initial” assignment of difference levels. In developing and 

selecting scenarios for evaluation consider the following: 

Likelihood of occurrence 

Possible consequences 

The timeliness of pilot discovery and correction 

d. Successful Test. The FSB members decide the outcome of the T3 consistent with 

previously agreed upon criteria and completion of LOF with appropriate pilot performance. 

Passing T3 leads to setting respective difference levels and validates differences training and 

checking at level B, C, or D between related aircraft. 

e. Failure of Test. Failure of T3 occurs with either failure of the check, agreed criteria, or 

unsatisfactory performance during the LOF portion of the test. In certain failure cases, T3 can 

lead to assignment of level E and a separate type rating. When a T3 failure is due to deficiencies 

in the proposed training program, at the discretion of the FSB, T3 may be repeated using 

different test subjects (pilots) following revision of the training program addressing the 

deficiencies. The following are examples that may lead to the assignment of level E differences: 
MM/DD/YY DRAFT AC 120-53B 

 Appendix 3 

Page 9 

(1) T3 experience or difficulties that show the need for assignment of training levels 

approaching typical initial/transition levels. 

(2) T3 pilot performance that indicates that devices or methods associated with level D 

are not adequate to achieve training or checking objectives. 

(3) Repeated failures of attempts to pass T3 test at level D training differences. In the 

case of retesting, new subjects may be required at the discretion of the FSB Chairman. 

NOTE: Repeated failure of test at level D differences by one or more 

subject’s (pilot) inadequate performance, that is not an individual subject’s 

failure due to sub-par or atypical personal performance as determined by the 

FSB, may lead to assignment of level E differences. 

6. CURRENCY VALIDATION-TEST 4 (T4). 

a. Test Purpose. The T4 test is a currency test that can be used when an applicant seeks 

relief from existing FSB currency provisions. In the context of this AC, currency addresses 

system procedural and maneuvering differences between related aircraft. T4 does not include 

takeoff and landing recency of experience. 

b. Test Subjects. Designated FAA FSB members. 

c. Test Process. If an applicant desires a change in the currency provisions, a T4 test may 

be conducted. This test may be done before or after the aircraft enters into service. In the event 

the test cannot be done before entry into service, the FSB established limits apply. Criteria that 

may be used by the FSB to set level B, C, D differences for currency for initial FSB 

determinations include the following examples: 

(1) Complex flight critical systems affecting control or navigation. 

(2) Critical nonnormal maneuvers differing between related aircraft (e.g., V1 engine 

failure, emergency descent, etc.), requiring one acceptable demonstration/training or checking 

event (typically 6 months but demonstration period may also vary by pilot position). 

(3) Secondary systems (e.g., Oxygen or auxiliary power unit (APU)). 

d. Successful Test. The FSB members decide the outcome of T4 consistent with previously 

agreed upon criteria. A successful test validates that the proposed less restrictive currency 

provisions are accepted as a means of compliance with applicable rules, provisions of this AC, 

and/or currency provisions and provide an equivalent level of safety.

e. Failure of Test. Failure indicates that the proposed less restrictive currency provisions do 

not provide an equivalent level of safety. At the discretion of the FSB, retesting may be 

appropriate. 

7. INITIAL OR TRANSITION TRAINING/CHECKING PROGRAM 

VALIDATION-TEST 5 (T5). 
Page 10 

a. Test Purpose. T5 test validates the applicant’s training course(s) at level E (new type 

rating). It is appropriate when: 

(1) A full initial or transition training/checking program requires validation; 

(2) An applicant seeks training credits between two aircraft with different type ratings (a 

typical goal under shortened training programs); or

(3) T2 or T3 are failed. 

b. Test Subjects. Designated FAA FSB members. 

c. Test Process. There are two methods to accomplish the T5 test process: 

(1) Full Initial or Transition Training/Checking Program Validation. This method is used 

when an applicant has developed an aircraft and seeks a new type rating without any credit for 

commonality with any related aircraft. The applicant develops a training program to qualify and 

check pilots in the candidate aircraft at level E differences. Subjects are trained, given flight 

proficiency checks and complete LOF in a process similar to that described in paragraph 5. 

(2) Shortened Transition Training/Checking Program Validation. This method is used 

when an applicant has developed an aircraft and seeks a new type rating and credit for 

commonality with related aircraft. The applicant conducts a handling qualities evaluation based 

on the applicant’s proposed ODR tables (similar to T2), followed by training and checking 

program validation (similar to T3). Subjects are trained, given flight proficiency checks and 

complete LOF in a process similar to that described in paragraph 5. 

NOTE: When an aircraft is assigned level E differences because of a failure 

of T3 test at level D differences, credit for successfully passing individual 

elements of the T3 test may be used as justification for not duplicating those 

elements in the T5 test. 

d. Successful Test. The FSB members decide the T5 outcome consistent with previously 

agreed upon criteria. A successful outcome of T5 validates the proposed training and checking 

programs. 

e. Failure of Test. Failing T5 Indicates the proposed training or checking programs require 

modification. A retest by mutual agreement between the FSB and applicant would normally be 

required. 

8. COMMON TAKEOFF AND LANDING CREDIT (CTLC)-TEST 6 (T6). 

a. Test Purpose. The applicant uses T6 when they seek credit between related aircraft 

toward the takeoff and landing recency of experience requirements of the applicable 14 CFR Part 

121.1229. 

b. Test Subjects. The test should consist of a sufficient number of pilots not trained or 

qualified in the candidate aircraft. These subjects will be drawn from the manufacturer, industry 
Page 11 (and 12) 

and the FAA that the FSB determines will represent a statistically relevant cross-section of 

operational pilots. The participants’ experience levels, type ratings and airplane currency should 

reflect the proficiency difference levels needed to validate testing assumptions. 

c. Test Process. Test subjects are first provided refresher training in the base aircraft to 

establish a baseline of proficiency. This training may be accomplished in an approved C or D 

FFS. The subject is then tested in the candidate aircraft, without any training in it, accomplishing 

a minimum of three takeoffs and landings without use of the autopilot. It may not be practical to 

conduct some tests in an aircraft. A FFS may be used to conduct these tests. Test subjects should 

be evaluated on their ability to fly the aircraft manually through takeoff, initial climb, and 

approach and landing (including the establishment of final landing configuration). The applicant 

should consider the effects on the takeoff and landing maneuvers for the following factors when 

designing the T6 test: 

(1) Aircraft weights. 

(2) Aircraft center of gravity. 

(3) Takeoff and landing crosswinds. 

d. Successful Test. The FSB members decide the outcome of T6 consistent with the FAA 

Practical Test Standards (PTS) by demonstrating that an equivalent level of safety can be 

maintained when full or partial credit for takeoffs and landings is given between the related 

aircraft. 

e. Failure of Test. The test subjects’ performance relative to the FAA PTS demonstrates an 

equivalent level of safety cannot be maintained when either full or partial credit for takeoffs and 

landings is given between the related aircraft.