Secret word caused the panic in airline

If you have watched james bond movies then you must know the impact of secret words.They are designed for the ease when situation is not favorable.They can change the situation dramatically .If they are used properly they are going to make a rainbow but if used improperly they can either harm you or situation can become worse.Here is the case of an airline.

An alert at Melbourne Airport on Friday night was caused when a Qantas Airlines pilot accidentally used the secret word for a hijacking when communicating with the tower. The pilot used the word shortly after the plane took off.

Upon landing, the plane was "quarantined" and searched for about 20 minutes before passengers were allowed to disembark.

I'm assuming the code word isn't an easy one, so I'm not sure how exactly this happened - and naturally they're not going to tell us the word.