Considerations related to aisle clearance with respect to seat installations Ref EASA CM No.: CM-CS-007 Issue 01 issued 25 July 2018 & Regulatory requirement(s): CS 25.815
Sofema Aviation Services (SAS) www.sassofia.com considers changes related to the regulations concerning the Aircraft Aisle Width.
Definition – Front Row Seat – A seat installed aft of an interior component other than a seat (e.g. a bulkhead, galley, lavatory, partition, class divider, etc.), a cross-aisle, or a passageway leading to an exit.
- Applicable over 20 pax
- Ref JAR/CS 25.815 Width of Aisle, published on the EASA website on 13/04/2014
- Ref JAR/CS 25.813 / AMC 25.815
- Ref FAA Advisory Circular 25-17A (Transport Airplane Cabin Interiors Crashworthiness Handbook)
CS 25.815 at Amendment 21 prescribes the following:
“The passenger aisle width at any point between seats must equal or exceed the values in the following table:
A narrower width not less than 23 cm (9 inches) may be approved when substantiated by tests found necessary by the Agency.”
FAA AC 25-17A provides the following guidelines on the determination of the width of the aisle between interior components other than seats:
- “When the measurement is not between seats but between other aisle constraints such as galleys, coat closets, storage compartments, etc., the minimum widths at the specified vertical distance above the floor still prevails.”
- It must be noted that JAR/CS 25.815 does not explicitly mention any flight phase. Therefore, the specified aisle width is required to be maintained during all phases of flight, and not only during taxi, take-off, and landing.
- Aisles are required to allow for rapid egress from the aeroplane in an emergency, but they also provide the means for crew members to access all parts of the cabin during aeroplane operations in order to address emergency conditions.
- Additionally, they allow passengers to return to their seats during turbulence. Not providing adequate aisles during flight may prevent the accomplishment of these needs.
- Aisle widths should be determined with seats and their moveable features in the most critical positions allowed by the design. This practice is based on the assumption that the seats could be in this configuration during an emergency.
- For example, when the in-armrest video monitor of a seat is deployed, the minimum aisle width of 51 cm (20”) might not be maintained above the height of 64 cm (25”) from the floor.
EASA Policy
Seat-moveable items are not expected to encroach into the minimum aisle width specified in CS 25.815 during any phase of flight.
- For the measurement of the aisle width, all the possible stable positions of moveable items (e.g. armrests, arm caps, deployable video monitors, tray tables, etc.) should be evaluated. Any non-self-supporting positions do not need to be considered.
- For example, armrest covers that only need to be lifted during the deployment /stowage of in-armrest tables, which are then closed by spring loading, do not need to be considered.
- In general, for the dimensional checks of aisles, cylinders of 51 cm (20”) and 38 cm (15”) diameters can be used. An aisle width that is fully compliant with CS 25.815 will allow a 51 cm (20”) diameter cylinder, placed above a 38 cm (15”) diameter cylinder with a height equal to 64 cm (25”), to slide along the aisle. In doing so, the lower cylinder may move relative to the upper one, but it should always remain entirely within the vertical projection of the upper cylinder.
EASA considers that the necessity to provide the occupants of seats with tables and monitors may result in minor encroachments into the minimum required aisle width.
Such minor encroachments can be considered to be negligible during phases of flight other than Taxi, Take-Off, and Landing (TT&L), and thus they should not be considered to be non-compliances with CS 25.815, provided that the criteria specified in the present Certification Memorandum are met.
EASA would like to highlight that it should always be a design objective to minimize the encroachment into the aisle of such moveable items.
The criteria for the identification of acceptable encroachments of seat-moveable items into the aisle width envelope required by CS 25.815 are the following:
- Encroachment into the dimensional aisle width limits of CS 25.815 is allowed:
o Only in phases of flight other than TT&L.
o Only for deployable video monitors, tables, and armrests for disabled passengers that are not electrically operated, under the limitations specified below.
Video monitors
- Encroachment into the minimum aisle width envelope defined by CS 25.815 is allowed for deployable video monitors mounted on front row seats.
- Encroachment is allowed when a change in the number of seats abreast (e.g. a central triple seat installed behind a central quadruple seat) results in the need to provide seats with deployable video monitors.
- If a deployable video monitor encroaches into the minimum aisle width envelope required by CS 25.815, all the following conditions should be met:
o The minimum aisle width in the worst-case stable position of the deployable video monitor should be at least 23 cm (9 inches).
(In the event of any encroachment allowed by i) above, it should be possible to restore the minimum aisle width envelope required by CS 25.815 through the application of a force on the video monitor that is not greater than 45 N (10 lbf) with a single sweeping motion using one hand.)
- For example, opening an armrest cover to stow the video monitor is not allowed.
- In any positions after deployment, regardless of whether they are stable or not, monitors installed on different seats should not come in contact with each other in such a manner that they could become impediments to egress from the aircraft.
Tables
- Encroachment into the minimum aisle width envelope defined by CS 25.815 is considered to be acceptable on all seat rows. If a table encroaches into the minimum aisle width envelope required by 25.815, all the following conditions should be met:
o The hinge mechanism of a deployed in-armrest table may have a length of up to 102 mm (4”) and a height of up to 51 mm (2”), measured from the top of the seat armrest, but it should not protrude into the aisle beyond the outside of the armrest.
o A table leaf with a thickness of a maximum of 25 mm (1”) may rest on an armrest, but it should not protrude into the aisle beyond the outside of the armrest.
Armrests for disabled passengers
Encroachment into the minimum aisle width envelope defined by CS 25.815 is allowed when following Aerospace Recommended Practice ARP5526, revision D, section 3.6.
Next Steps
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Aircraft, aviation, Aviation Training, Compliance, EASA, EASA compliant, CS 25, EASA CS-25, Cabin Certification, Aisle, EASA CM No.: CM-CS-007, Aircraft Aisle Width
