June 25, 2021, ©. Leeham News: We are closing in on our aircraft project, where we will go through an aircraft development from A to Z and look at how certification rules govern our work.
Before we decide what aircraft to develop, let’s look at how the certification rules break the market into segments based on cabin seating.
In previous parts of the series (Part 5 and 6), we saw that the Safety certification rules for the aircraft and the Operating rules for the airline combined to divide the market in two segments:
Equipment and proof of safety vary for these aircraft, but these classes do not require a crew above the two pilots. Is there an additional category of aircraft above Normal and Transport Category aircraft? No, there isn’t.
This means there isn’t anything in rules that makes certifying a 51-seat aircraft more complex than a 50-seat or larger aircraft, as we stay in 14 CFR Part 25 for aircraft certification, from 20 seats and up.
There are other reasons there is a segment break for airliners at 50 seats.
Under FAA Part 121 or EASA Part-CAT, one flight attendant is required when the seating capacity exceeds 19. An additional flight attendant is needed when the seating capacity exceeds 50.
The marginal revenue from a few extra passengers above 50 does not justify the extra crew member cost. Keep in mind; it’s not only the personnel costs that increase; the aircraft OEM must install an additional cabin attendant seat and associated equipment on the aircraft as well. The 50-seat configuration, as a result, makes more economic sense if our routes have around 50 passengers per departure.
In the United States, so-called Scope Clauses between the mainline Pilots and their Carrier constrain the size and the number of regional aircraft the Carrier can outsource regional traffic to.
Here the negotiated size brackets are 50, 70, and 76 seats with a specified Maximum TakeIOff Weight (MTOW) per category (an indirect way to restrict the length of routes the aircraft can fly).
The different size brackets have limitations on how many aircraft each bucket can have. The 50-seat category is generally the least restrictive in terms of fleet size. Therefore, in the US outsourced market (80%-90% of the US regional aircraft market), having 51 passenger seats pushes the product into a larger Scope category, which is more restrictive in terms of fleet size, on top of requiring an extra cabin attendant.
The end result is size segments for the US market of 9, 19, 50, 70, and 76 seats. Above these, aircraft are no longer operating under Scope agreements, and the next natural limit is 100 seats, above which three flight attendants are required. At 150+, this changes to four, etc.
The limits of 50, 100, 150, 200, etc., are relevant in the markets outside the US, with the requirement for an additional flight attendant when passing these seat limits.
As the costs for an extra cabin attendant become less troublesome as the seating passes 100, the market segmentation around these limits is less pronounced once above 100 seats.