Appendix A
05/11/10 AC 25.785-1B Appendix A Appendix A Direct View Determination for Visually Divided Zones and Airplane Cabins In order to permit a more performance based assessment, the following relationship of direct view and flight attendant head movement has been constructed. Figure A-1 shows an envelope of cabin view as a function of the amount of head movement utilized. The curves depicted are based on previously accepted methods of compliance.
Cabin Zone Acceptance : For each zone in the cabin, any combination of lateral head movement and percentage of seats in view that is above the lower curve is considered acceptable. The airplane cabin zone direct view may be established using head movement as necessary at each fight attendant seat to achieve the total percentage, provided such movement is permitted by the restraint system when fastened.
~ • .: ,!
.:, • • Ill ---- Total Cabin\llewvs. Head Mo vement ...
• - cabin Zone vi ewvs. Head Movement • ..
: • • ~ • ~ 2 4 6 10 12 14 16 L3 t er a, I He a d M o v ement in In c he s Figure A-1 NOTE: Measured head movement is from common reference point, such as the eye reference point of the normally seated occupant.
Total Cabin Acceptance : The simplest method to determine total cabin view is to utilize the same amount of head movement at each flight attendant position and determine the total number of seats in view, based on the curves. In this case, the zonal criteria and the total airplane criteria may be treated independently. The airplane satisfies the criteria as long as the total number of seats in view is above the “total cabin” curve at some point (i.e., using the same amount of head movement at each flight attendant seat). The total cabin view should be established in 5 percent increments (rounded up), since the curves are not refined enough to be more precise. An A-1
Appendix A
05/11/10 AC 25.785-1B Appendix A applicant may simply choose to select a fixed amount of head movement and assess the total cabin view at that point. Alternatively, the curves as shown in Figure A-2 may be developed and the point on the curve where maximum cabin viewing occurs may be established. As noted above, each zone may be assessed to determine its maximum direct view even if the assessment criteria are different among the specific zones (different amount of head movement at each flight attendant seat).
The following example illustrates one way to do this.
Example : An airplane with three divided zones, with a total passenger capacity of 375, and zone capacities of 50, 175 and 150. Five flight attendants (out of a required 8) participate in direct view as follows: Flight attendants 1 and 2 view zone 1, flight attendants 3 and 4 view zone 2 and flight attendant 5 views zone 3.
Each flight attendant’s actual direct view coverage as a function of head movement is shown on Figure A-2 (note that the movement is limited by the restraint system): ---- Tot al C abin View v s. He ad M ov ement Cm in Zo ne view vs. Head M oveme nt
I
10 ++ ---------------------------- --; 0 +- --~---~---~---~--~---~---~-------4 0 2 4 6 8 1 0 12 1 6 Lateral He ad Mo vement in Inche s Figure A-2 In Figure A-2, flight attendants 1,3 and 5 have direct view that is unaffected by head movement.
Flight attendants 2 & 4 can improve their view with a limited amount of head movement, although for flight attendant 4 the view diminishes beyond a certain point. The overall assessment of acceptability can be made as follows: A-2
Appendix A
05/11/10 AC 25.785-1B Appendix A a. All flight attendants have adequate zone viewing since each line is above the zone viewing curve at some point.
Peak zone viewing is as follows: Flight attendant 1 ~40 percent of zone 1 or 20 seats.
Flight attendant 2 ~58 percent of zone 1 or 29 seats.
Flight attendant 3 ~81 percent of zone 2 or 142 seats.
Flight attendant 4 ~72 percent of zone 2 or 126 seats.
Flight attendant 5 ~81 percent of zone 3 or 121 seats.
b. The total cabin viewing can be established by a point on the zone curve at which the sum of the individual zone views exceeds the total cabin view curve, for a given amount of head movement. For this example arrangement, a large portion of the cabin is visible at 4” of head movement. With 4” of head movement, the corresponding total cabin view is read at ~70 percent. As long as a total of 70 percent of the cabin is in direct view of the combined 5 flight attendants using no more than 4” head movement, the arrangement is acceptable. For this arrangement, that would be 263 seats.
c. For this airplane, total coverage is no worse than the sum of the maximum zone coverages, or 29??+142+121 or 292 seats, so the arrangement satisfies the criteria.
d. Figure A-3 illustrates the amount of viewing coverage provided in each zone by each flight attendant seat position (note that the figure is representative only, and cannot be used to estimate, or extrapolate direct view). As can be seen, there is some degree of redundancy in the zone viewing among flight attendants, but in this case no flight attendant’s view is completely redundant with any other. In actuality, the total cabin direct view is greater than shown above since zones 1 and 2 are viewed by more than one flight attendant.
F /Α 2 175 Pax F /Α 4 Seats
Zone 2 Zone 1 Zone 3
150 Pax F /Α 3 F /Α 1 50 Pax Seats Seats F /Α 5 Figure A-3 A-3