When selecting your aviation raft, you may be required to provide flotation for all of your passengers by FAA regulation or for Part 91, you want to have a raft onboard. In just looking at the raft, it can be hard to discern how many people will fit. For all FAA TSO C70a approved rafts, the rafts are categorized by passenger limits.
In general, a life raft's capacity is defined by its total size in floor area and inflated buoyancy. When determining what raft you’ll need, you’ll want to consider the total maximum number of your passengers your plane can carry.
Calculating capacityWhen it comes to FAA regulations, the rated and overload capacity of a life raft is the number of survivors the raft can hold, with a set amount of space per person and buoyancy. This is calculated based on the sitting area within the raft and FAA TSO C70a sets a minimum of 3.6 sq. feet per person.
Alternatively, the capacity can be determined by the number of seating areas within the raft, without overlapping spaces and with a back support of no less than 8 inches. The seating space may be no less than the pictured:
Overload capacityBesides their rated capacity, aviation rafts also have an overload capacity. To calculate the overload capacity, the FAA mandates 2.4 sq. feet per person. This typically amounts to half of the rated capacity, plus the rated capacity. So, in a 4 person rated raft, the overload capacity would be 6 people.
When you select the capacity raft you want, you should rely on the listed rated capacity, never on its overload capacity. If carrying six people, get no less than a six person raft, not a four person raft with six person overload capacity. This will give you passengers slightly more room in the crowded raft, making an emergency situation more comfortable.
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