U.S. Department

of Transportation

Federal Aviation

Administration

Advisory

Circular

Subject: Flightcrew Member Rest Facilities Date: DRAFT

Initiated by: AFS-200

AC No:

AC 121-31A

Change:

1. PURPOSE. This advisory circular (AC) describes an acceptable means, but not the only 

means, of compliance with Title 14 of the Code of Federal Regulations (14 CFR) “proposed” 

part 117. Prior to utilizing onboard crewmember rest facilities, all 14 CFR parts 121 and 135 

certificate holders must obtain Federal Aviation Administration (FAA) approval regarding the 

classification and adequacy of onboard rest facilities. The Aircraft Evaluation Group (AEG) is 

responsible for developing the technical standards for crewmember sleeping quarters and rest 

facilities. Part 117 identifies sleeping spaces as “Rest Facilities” and part 135 identifies them as 

“Sleeping Facilities.” These terms are interchangeable for the purpose of this AC.

a. Provision of Crewmember Rest Facilities. This AC references criteria that may be used 

for the design and installation of crewmember rest facilities on transport category aircraft 

capable of augmented flightcrew operations. If, in addition to providing rest facilities, an 

operator voluntarily provides an area for storing personal articles and for changing clothing, then 

this AC provides useful information and advice for their design and installation.

b. Guidance for Other 14 CFR Parts. For operators conducting operations under parts 

other than parts 121 and 135, this AC references FAA-acceptable criteria and guidance that may 

be useful for the design and installation of flightcrew sleeping quarters and rest facilities on 

transport category aircraft capable of long-range operations with augmented or enlarged 

flightcrew complements.

2. RELATED 14 CFR SECTIONS.

a. 14 CFR Part 25 Subpart D, Design and Construction. Part 25, §§ 25.789, 25.791, 

25.831, and 25.853, 25.1301, 25.1445, and 25.1529.

b. Part 121 Subpart J, Special Airworthiness Requirements. Part 21, § 121.285.

c. Part 121 Subpart K, Instrument and Equipment Requirements. Sections 121.311(b), 

121.317, 121.327, and 121.329.

d. Part 135 Subpart B, Flight Operations. Part 135, § 135.128(a).

e. Part 135 Subpart C, Aircraft and Equipment. Section 135.157.
AC 120-31A DATE

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f. Part 135 Subpart F, Crewmember Flight Time and Duty Period Limitations and 

Rest Requirements. Section 135.269(b)(5).

g. 14 CFR Part 125 Subpart B, Certification Rules and Miscellaneous Requirements.

Part 125, § 125.37(b).

h. Part 117, Flightcrew Member Duty and Rest Requirements.

3. RELATED READING MATERIAL. This AC and Society of Automotive Engineers 

(SAE) Aerospace Recommended Practice (ARP) 4101/3, Crew Rest Facilities, should be used in 

conjunction with ARP4101, Flight Deck Layout and Facilities, for the design and installation of 

crewmember rest facilities. The following SAE documents may also be applicable and may be 

obtained for a fee from:

SAE Industry Technologies Consortia

161 Thorn Hill Road

Warrendale, PA 15086

724-776-4970

institute@sae.org

a. SAE ARP1323, Type Measurements of Aircraft Interior Sound Pressure Levels 

During Cruise.

b. SAE ARP4245, Quantities for Description of the Acoustical Environment of the 

Interior of the Aircraft.

c. Additional Information. The following report provides additional information and detail 

concerning crewmember rest facilities onboard aircraft.

• Netherlands organization for Applied Scientific Research (TNO) Report, Extension of 

Flying Duty Period by In-Flight Relief, project number 032.13267, dated 

September 2007.

4. DEFINITIONS. For the purposes of this document, these terms are defined as follows:

a. Rest Facilities. Means a bunk, seat, room, or other accommodations that provides a 

crewmember with sleep opportunity. (TNO Report, part 117, § 117.3.)

b. Free Space. An area designated for the use of the crew to change and stow clothing.

(AC 121-31, SAE ARP4101/3 definition.)

c. Class 1 Rest Facility. Means a bunk that allows for a horizontal flat sleeping position 

and is separate from the flight deck and passenger cabin in an area that is temperature controlled, 

allows the crewmember to control light, and provides isolation from noise and disturbance. 

(Section 117.3, sound definition SAE ARP4101/3 and horizontal flat definition SAE 

ARP4101/3.)
DATE AC 120-31A

Par 4 Page 3

d. Class 2 Rest Facility. Means a seat in an aircraft cabin that allows for a flat or near flat 

sleeping position, is separated from passengers by a minimum of a curtain to provide darkness 

and some sound mitigation, and is reasonably free from disturbance by passengers or 

crewmembers. (Section 117.3.)

e. Class 3 Rest Facility. Means a seat in an aircraft cabin or flight deck that reclines at least 

40 degrees and provides leg and foot support. (Section 117.3.)

f. Sleeping Surface. Any surface such as a bed, bunk, or seat that meets the guidelines 

referenced in this AC.

g. Significance of Rest Facility Classification. Each rest facility has a classification 

ranking from 1 through 3 that defines the flight duty period limits, predicated upon the 

classification of rest facility, for augmented flightcrew operations. A class 1 facility provides for 

the longest flight duty periods, a class 2 provides for the second longest flight duty period, and a 

class three provides for the third longest flight duty periods.

5. OPERATIONAL CONSIDERATIONS.

a. Crewmember Rest Facilities. The location of crewmember rest facilities in an aircraft is 

an important decision that should be based on an analysis of the following factors to ensure that 

an adequate environment is provided to enable crewmembers to obtain sleep of adequate quality.

(SAE ARP4101/3, AC 121-31.)

(1) There should be a sufficient number of sleeping surfaces provided to accommodate 

the maximum number of crewmembers that would be expected to use these surfaces during the 

same period of time. (SAE ARP4101/3, AC 121-31.)

(2) For crewmember sleeping quarters, adequate volume should be provided for sleeping. 

The recommended volume per individual is 1.0 m3 (35 feet3). (SAE ARP4101/3, AC 121-31.)

(3) For crewmember rest facilities, adequate volume should be provided for sleeping, 

personal articles storage, and changing of clothes. The following volumes are recommended:

• Individual sleeping space volume: 1.0 m3 (35 feet3). 

(SAE ARP4101/3, AC 121-31.)

• Free space adjacent to the sleeping surfaces for ingress and egress and changing 

of clothes: 1.85 m3 (65 feet3). (SAE ARP4101/3, AC 121-31.)

b. Sleeping Surfaces. The following are acceptable criteria for sleeping surfaces:

(1) Class 1 facility.

• Dimensions for each sleeping surface of 1.98 x 0.76m (78 x 30 inches).

(SAE ARP4101/3, AC 121-31.)
AC 120-31A DATE

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• The sleeping surfaces should be designed so that they are flat and as level as 

practicable during cruise flight. (SAE ARP4101/3, AC 121-31.)

• Suitable means should be provided to ensure occupant privacy for each sleeping 

surface area; e.g., curtains in an over-and-under arrangement or a divider curtain 

in a side-by-side arrangement. (SAE ARP4101/3, AC 121-31.)

(2) Class 2 rest facility.

• Is a seat in an aircraft cabin that allows for a flat or near flat sleeping position, it 

should recline to at least 80° back angle to the vertical and have a seat width at 

least 20 inches. Examples are so-called "Lie-Flat" seats, or "Flat Bed" seats.

(Section 117.3, TNO Report, Recommendation paragraph 5.2.5.)

(3) Class 3 rest facility.

• Is a seat in an aircraft cabin that reclines to at least 40° from the vertical and 

providing sufficient leg and foot support. (Section 117.3, TNO Report 

recommendation paragraph 5.2.5.)

c. Isolation. The following are acceptable criteria for isolation of flightcrew rest facilities.

(1) Class 1 rest facility.

• The crewmember rest facility should be in a location where intrusive noise, odors, 

and vibration have minimum effect on sleep. The spectrum of the sound within 

this facility should be limited to broadband without annoying tones. Special 

attention should be given to the existence of doors, passenger convenience 

systems, public address systems, etc., in the immediate area to minimize intrusive 

noise and ensure they have minimal effect on sleep. A noise level during cruise 

flight in the range of 70 to 75 dB (A) is considered a reasonable design objective. 

(AC 121-31 SAE ARP4101/3, SAE ARP1323, SAE ARP4245, additional 

language from the Air Transportation Division (AFS-200) Memo to Long Beach 

(LGB)-AEG March 26, 2009.)

(2) Class 2 rest facility.

• A common grouping of seats (row subsection) that should be shared only by other 

crewmembers. The seat should be separated from the cockpit and passengers by 

acoustic curtains or panels and provisions for darkening and sound mitigation of 

the sleep environment should be available. (TNO Report Recommendation,

paragraph 5.2.5.)

d. Environmental (Class 1 Rest Facility Only). Airflow and temperature control should 

provide a uniformly well-ventilated atmosphere free from drafts, cold spots, and temperature 

gradient. The FAA recommends that the rest facility be designated a nonsmoking area.

(AC 121-31 SAE ARP4101/3, SAE ARP1323, SAE ARP4245.)
DATE AC 120-31A

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e. Public Address (PA) System (Class 1 Rest Facility Only). The FAA recommends that 

the PA system or an alternative means should include provisions to provide only relevant 

information to crewmembers in the crewmember rest facility; e.g., in-flight emergencies, aircraft

depressurization, or preparation of compartment occupants for landing. (AC 121-31, SAE

ARP4101/3, SAE ARP1323, SAE ARP4245.)

f. Emergency Lighting (Class 1 Rest Facility Only). Emergency lighting should be 

provided in crewmember rest facilities. (AC 121-31, SAE ARP4101/3, SAE ARP1323, SAE 

ARP4245.)

g. Stowage and Restraints (Class 1 Rest Facility Only). In accordance with the applicable 

14 CFR, suitable personal articles stowage and occupant restraint systems must be provided to 

each occupant of sleeping surfaces as well as each occupant of any seats located in crewmember 

rest facilities. (AC 121-31, SAE ARP4101/3, SAE ARP1323, SAE ARP4245.)

h. Emergency and Other Equipment (Class 1 Rest Facility Only).

(1) Approved oxygen equipment must be provided for each crewmember that uses a 

sleeping surface and crewmember rest facility seat, including an aural alert to awaken a sleeping 

crewmember. (AC 121-31, SAE ARP4101/3, SAE ARP1323, SAE ARP4245, language 

developed by AEG’s AC 121-31 Draft for March 2000.)

(2) There should be one or more lighted "FASTEN SEAT BELTS" signs within the view 

of the occupants of each sleeping surface and seat located within a crewmember rest facility. 

These lighted signs should be dimmable for sleeping purposes. (AC 121-31 SAE ARP4101/3, 

SAE ARP1323, SAE ARP4245, language developed by AEG’s AC 121-31 Draft for 

March 2000.)

(3) If the operating rules and the operator permit smoking in a crewmember rest facility, 

the following apply:

(a) One or more lighted "NO SMOKING" signs within the view of the occupants of 

each sleeping surface and seat located in a crewmember rest facility should be provided. These 

lighted signs should be dimmable for sleeping purposes; and

(b) An adequate number of self-contained, removable ashtrays for each seat in the 

facility must be provided. (Language developed by AEG’s AC 121-31 Draft for March 2000.)

(4) If the operating rules and the operator do not permit smoking in a crewmember rest 

facility, then one or more “NO SMOKING” placards legible to the occupants of each sleeping 

surface and seat located in the facility must be provided.

(5) A means, such as an interphone, must be available for the cockpit crewmembers to 

communicate with the sleeping crewmember. (Language developed by AEG’s AC 121-31 Draft 

for March 2000.)
AC 120-31A DATE

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6. REQUESTING APPROVAL FOR THE USE OF FLIGHTCREW MEMBER REST 

FACILITIES. Before using an aircraft with an augmented flightcrew, the certificate holder must 

ensure the aircraft onboard rest facility receives FAA qualification meeting one of the three 

classifications prescribed in part 117. The certificate holder also must receive operations 

specification (OpSpec) AXXX authorizing them to conduct augmented operations.

a. Qualification and Classification of Flighcrew Rest Facilities.

(1) Before conducting augmented flightcrew operations, the certificate holder must have 

a qualification analysis statement (QAS) for each specific aircraft used for augmented flightcrew 

operations that qualifies the rest facility as either a class 1, 2, or 3. The classification of the 

onboard rest facilities (i.e., class 1, 2, and 3) defines the maximum flight duty period an 

augmented flightcrew may operate. The QAS is a statement and analysis qualifying the rest 

facility as meeting one of three rest facility classifications. A class 1 rest facility provides for the 

longest flight duty period; whereas, a class 3 provides the shortest flight duty period of the three 

classes.

(2) Evaluation and qualification of onboard rest facilities will follow one of three paths; 

newly installed class 1, newly installed class 2 and 3, and previously qualified rest facilities 

(class 1, 2, or 3).

b. Qualifying Newly Installed Class 1 Rest Facilities.

(1) Newly installed onboard class 1 rest facilities must be evaluated and qualified by the 

AEG in concert with the appropriate Aircraft Certification Office (ACO). The AEG will 

coordinate with the certificate holding district office (CHDO) throughout the evaluation to 

involve the principal operations inspector (POI) and principal maintenance inspector (PMI) 

having oversight responsibility of the certificate holder. If the evaluation meets the specifications 

prescribed in part 117, the AEG may issue a QAS for that aircraft.

(2) Early identification of the certification project is essential for ensuring a timely 

evaluation of the facility for adequacy. The certificate holder should make a request to FAA for 

the installation and use of crewmember rest facilities. Requests for approval should include 

evidence that the rest facility has been certified for occupancy in accordance with the 

requirements of part 25 as being part of the original type-certificate (TC), amended TC, or 

Supplemental Type Certificate (STC).

(3) Proposed instructions for continued airworthiness should be included with the 

request. Also, in the event that the design of the rest facility requires some preparation by the 

crew prior to use, such as expanding sections, the evaluation request should include appropriate 

preparation procedures, recommended qualification/training requirements, and proposed actions 

to be taken in the event that the facility becomes inoperative.

(4) The evaluating AEG will complete a report on the QAS for that aircraft including any 

qualifications regarding the findings; i.e., location of toilets, galleys, etc., in the near vicinity of 

the facility such that if changes were made in the near environment of the facility a re-evaluation 

of the adequacy of the facility would be required. This report should be made a part of the

aircraft’s permanent record.
DATE AC 120-31A

Par 6 Page 7

c. Qualifying Newly Installed Class 2 and 3 Rest Facilities. New installation of class 2 

and 3 crewmember onboard rest facilities will be evaluated by the POI in concert with the PMI 

having oversight responsibilities of the certificate holder. The PMI will inspect the rest facility 

for proper installation. The PMI or POI will conduct a visual operational inspection to determine 

the rest facility currently meets the specifications prescribed in part 117. Once the POI and PMI 

have determined the rest facility meets either the class 2 or 3 specification, the PMI may issue a 

QAS for that aircraft. The AEG will serve in an advisory role to the CHDO.

d. Requalification of Previously Qualified Rest Facilities.

(1) Evaluation of crewmember onboard rest facilities previously qualified will be the 

responsibility of the POI in concert with the PMI. The POI and PMI will inspect the QAS to 

ensure the qualification meets the classification of rest facility the certificate holder intends to 

use. The POI or PMI will conduct a visual operational inspection to determine the rest facility 

currently meets the specifications prescribed in part 117. The AEG will serve in an advisory role 

to the CHDO.

(2) Once the aircraft’s onboard rest facility has been qualified, the FAA will issue a QAS 

that will remain part of the aircraft permanent records. The QAS will remain in effect until a 

modification to the rest facility or a component of the rest facility that renders it noncompliant 

with the specifications prescribed in part 117, or the FAA determines the rest facility no longer 

meets the specification(s) prescribed for that classification.

(3) Modifications and repairs that alter any part of the original specifications of the rest 

facility may disqualify the rest facility from the previously qualified classification. In the event 

an inoperative component or installed equipment associated with the rest facility is covered 

under the certificate holder’s approved minimum equipment list (MEL) for that aircraft, and 

appropriately deferred in accordance with the certificate holder’s procedures, the certificate 

holder must comply with the applicable provisos for that deferral. If the deferred item has been 

corrected and returned to service, the rest facility qualification will resume without a subsequent 

evaluation and qualification by the FAA. Otherwise, the aircraft may only be used for 

un-augmented flightcrew operations until such time as the deferred item(s) have been corrected 

and returned to service.

(4) ”Draft” OpSpec AXXX. The certificate holder must also have “draft” OpSpec AXXX 

issued containing specific information including the aircraft N number, make/model/series, 

classification of rest facility, and number of sleep surfaces. “Draft” OpSpec AXXX authorizes 

specific aircraft for flightcrew member augmentation using the onboard flightcrew rest facilities 

listed. Additionally, the certificate holder must develop augmentation operating procedures 

relative to the use of the specific onboard rest facilities. The air carrier should submit these 

procedures at the same time it applies for FAA qualification of a flightcrew rest facility.

Augmentation operating procedures, at a minimum, must include the following:

• Flightcrew augmentation procedures,

• Use of augmentation table in part 117,
AC 120-31A DATE

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• MEL procedures, if applicable,

• Loss of cabin altitude,

• Emergency communications,

• Smoke in the cabin, and

• Fires in the rest facility.

(a) ”Draft” OpSpec AXXX authorizes the certificate holder to conduct augmented 

flightcrew operations using a specific aircraft and a qualified rest facility. This OpSpec must 

contain the following information: the aircraft N number, make/model/series, classification of 

rest facility, and number of sleep surfaces.

(b) Once the qualification process and visual operational inspection are complete, 

the QAS has been issued, and the POI is satisfied with the air carrier’s operating procedures, the 

principal inspector may issue “Draft” OpSpec AXXX in accordance with the guidance in FAA 

Order 8900.1, Flight Standards Information Management System (FSIMS).

7. CONTACT INFORMATION. For more information about the content of this AC, please 

contact AFS-200, at 202-267-8166.

John M. Allen

Director, Flight Standards Service