SINGAPORE - Singapore Airlines (SIA) and SilkAir announced on Friday (Dec 15) that they will introduce a new airfare pricing structure.

The new fare types will be introduced on Jan 20, 2018, for all tickets sold worldwide.

The revisions include three new fare types for economy class bookings - Lite, Standard and Flexi.

With the change, those travelling on the lowest economy class - Lite - will have to pay a fee for advance seat selection.

SIA said on its website that this fee will start from US$5 (S$6.70) per flight segment.

Previously, there were no charges for all economy class bookings.

Alternatively, travellers can select a seat for free when they check in online, 48 hours before a flight.

Advance seat selection for business class, premium economy, suites and first class is complimentary.

Here's a look at how much advance seat selection on other airlines costs:

1. Emirates

Gulf carrier Emirates charges a fee of between US$15 (S$20.20) and US$35 for advance selection of a standard seat in economy class.

Those who want to sit closer to the front of the plane have to pay at least US$25 for a preferred seat.

The airline, however, offers free seat selection during online check-in up to 48 hours before a flight.

There is complimentary seat selection for passengers flying business class or first class.

2. Qatar Airways

All passengers travelling on state-owned carrier Qatar Airways are able to request a seat in advance for free after completing their online booking.

3. Cathay Pacific

Those travelling on selected flights in economy class on the Hong Kong-based airline will not be able to select their seats in advance.

These include passengers with economy save and economy supersaver tickets.

They can do so only up to 48 hours before a flight, when checking in online.

All other passengers, including those in standard economy, first and business class, can request a seat at any time up to 55 hours before their flight departs.

4. British Airways

Passengers with a basic ticket on British Airways' economy class have to pay to reserve their seat.

They can do so after they have made their booking until check-in opens.

Alternatively, passengers will be allocated a seat for free when check-in opens, and they can then pay a fee to change their seat.

The cost of reserving a standard seat on domestic and European flights starts from £7 (S$12.70). On international flights, the fee starts from £20.

The airline, however, has exceptions for those travelling as a family, or in groups of more than nine people. In these cases, seats will be allocated free.

5. All Nippon Airways (ANA)

Japan's largest airline ANA allows seats to be assigned in advance for all domestic and international flights operated by the ANA Group.

This option is not applicable for its code-share flights where the operating airline's policy does not allow advance seat selection.

However, in some cases, passengers can request a seat preference (aisle or window), even if they cannot request a specific seat.

6. EVA Air

On Taiwanese airline EVA Air, advance seat selection is available free for all individual ticketed passengers 24 hours before their scheduled flight departure date.

Those holding group tickets will be assigned seats.

7. Qantas

Standard seat selection is free for all passengers on Australian carrier Qantas, except for those travelling in international economy on sale fares.

These passengers can select their seat for a fee of A$15 (S$15.50) on international short-haul flights, and A$35 for international medium- and long-haul flights.

There is no fee for passengers who select a seat during check-in within 24 hours of departure.