All airlines have flight cancellations from time to time. The difference is how they communicate this to their customers. In many cases they will provide a reason (I think they should always provide a reason, but as
Pandaroo found out, this is not always the case. Then again, sometimes its difficult to believe the reasons that have been provided, so truth and reality may not always be fully aligned.
Some common reasons for cancellations:
- Mechanical fault
- Weather at origin, destination or en-route
- Crew operational limitations (generally due to late arrival and now out of hours)
- Airport or other infrastcuture failures
- Airspace is closed, such as in USA after Sept 11, 2001
Most other problems generally should only result in delays. However, significant delays can result in cancellation when all passengers have been reaccommodated on other flights.
In my view, a valid (and hopefully honest and accurate) reason should be provided upon request when a flight is cancelled. However, its not going to make the flight magically uncancelled, so more important is how the airline deals with reaccommodating the passengers to get them to their destination in a timely manner.