Code shares and other related evils
Code sharing is when one airline puts its code on another's flights. An example is British Airways, Cathay Pacific and Qantas, which put each others' codes on a variety of flights, cementing their relationship as Oneworld alliance partners.
It allows, for example, Qantas to place its code on BA's domestic flights from Heathrow. Similarly, BA places its code on Qantas's flights from Sydney to New Zealand and on Cathay's flights from Hong Kong to Auckland.
At first sight, there are a lot of advantages to code-sharing for both passengers and airlines.
From the passenger's point of view, it permits seamless transfers and through-checking of baggage onto the final destination. It also simplifies booking - all the above permutations can be booked in one transaction on BA's website.
Then there is the flexibility it offers to passengers. On the Auckland itinerary, passengers can take advantage of the code-share between the three carriers by flying Heathrow-Los Angeles-Auckland one way using BA and Qantas. On the return, passengers can travel the other way around the world via Hong Kong, using Cathay's flight from Auckland and then BA or Qantas for the final leg to London.
For the airlines, the advantage is that some lesser-known brands are able to sell tickets in countries where their names have little recognition in comparison to the mega-carriers. For example, Air New Zealand sells connections to UK airports on its website on behalf of BMI, with which it codeshares, giving BMI sales it would not otherwise have gained.
There is, however one distinct disadvantage to codesharing for the passenger, especially for people who do not book their own flights. The problem is one of consistency. If you are used to flying with one carrier and suddenly find that, due to a codeshare agreement you hadn't noticed that you are flying with another, it can come as a nasty surprise.
For example, Virgin Atlantic's New York flights all depart from Heathrow. However, it sells a Gatwick flight on its website, which is operated until the end of summer 2008 by Continental Airlines under a codeshare.
The problem is obvious for the unsuspecting Virgin customer who suddenly finds themself on a Continental flight - simply that Continental's current business cabin, with its inclined seat, is not a patch on Virgin's Upper Class, with its fully-flat beds and bar area. Moreover, Continental uses a narrow-bodied Boeing 757 on some Gatwick-New York flights, whereas Virgin's fleet is all wide-body.
Code-share flights can also confuse the booking process, as when airlines load all the different codes into Global Distribution Systems, it can make their services appear more frequent than they actually are.