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As it stands now, airlines must have one flight attendant on board for every 40 passengers, except when flying smaller regional jets. For the 50-seat regional jets, the airlines are allowed to use a ratio of one attendant for every 50 available seats, the crew formula they'd like extended as an option for all flights.

The issue is particularly important to WestJet Airlines Ltd. because the Calgary-based airline makes heavy use of Boeing 737s, some of which carry 125 passengers. At the one attendant per 40 passengers ratio, that means the airline must add a flight attendant for just five passengers when the aircraft is full.