Here is the 2nd part of 'Widebody aircraft seating classes' articles.

It is not comfortable for passengers to sit in Economy class seats for over 10 hours, epsecially when the seat pitch is narrow, say 30". So some airlines, like United & Virgin Atlantic, invented Economy Plus class of wider seat pitch.

The Economy Plus seats have seat pitch of 36-40", and all airlines except United have Economy Plus seats wider than Economy Class seats (7 abreast vs 8 abreast for Airbus widebodies, 8 abreast vs 9/10 abreast for B777/B747). There are no more than 40 Economy Plus seats in an aircraft except for United, which the seats are the same as Economy class except for seat pitch.

One major drawback of most Economy Plus class except for British Airways & Virgin Atlantic is only passengers paying full fare or frequent flyer club members can enjoy the benefit of Economy Plus class. Passengers travelling with restricted or group tickets cannot enjoy the wider seats.

Some airlines, like Mayalsia Airlines & US Airways, however, do not introduce Economy Plus class, and solve the problem of uncomfortable long trips by increasing Economy Class seat pitch instead, from 32" to 34". I think this is better than making Economy Plus class without increasing seat pitch of Economy class, as this makes every Economy Class passengers can have more comfortable trip.

China Airlines of Taiwan is the first airline to use cradle seats in its Economy class of A340, so the lower cushion is tilted upwards when the seat is reclined, to make more support for the passenger when sleeping.