United said premium economy should be available on all domestic flights by mid-March.

However, due to delays to the new premium economy seats, the debut was pushed back to April 19.

Premium economy is often limited to just small extras like more leg room, free meal and drinks.

In premium economy, business- and first-class cabins, the rises are even more pronounced.

Premium economy is a coach section with better seats and service and slightly higher fares.

The airline was one of the first carriers to introduce the premium economy class, which it debuted in 1991.

First class was removed, with an upgraded business class and a new premium economy section installed.

Premium economy can encompass differences from economy class such as:

Premium Economy seats are offered on select aircraft, boasting a 85+cm (34+inches) seat pitch.

Toronto-Munich will also feature premium economy class seating beginning in September 2013.

MAXjet's target market was premium economy and "savvy" business class passengers.

For example, a round-trip ticket in premium economy class now requires 5 premium-class round trips rather than 11.

Passengers flying premium Economy will also be able to make use of a dedicated check-in desk at selected airports.

In October 2008 the economy section was eliminated in favour of more premium economy seating.

If they want a little extra legroom, and choose to fly in premium economy, they must cough up a staggering £648.

Some airlines no longer offer Premium economy:

It will differ somewhat from other Australian budget airlines; offering business, premium economy and economy seats.

The Premium economy class is not regulated among airlines, and can be much different between airlines and routes.

Is there a religious leader anywhere without feet of clay (to put it politely) or at least a premium economy frequent flyer loyalty card?

It also declared that those passengers flying in premium economy would continue to pay the same rate as those travelling in first class.

The aircraft can accommodate 302 passengers in the basic three-class layout (business class, premium economy and economy).

Carriers create extra space in premium economy by removing one row of seats and then redistributing the space.

Main Cabin Select is Virgin America's premium economy product.

Premium economy is a travel class offered on some airlines to give better experience than economy class but for much less money than business class.

Economy Comfort is the premium economy product offered on KLM flights.