So my little sister wants to join as cabin and received a conditional discharge for ABH which runs out in June next year, which means she does not have to disclose this information as it is not classed as having a criminal record.

Does this mean she will be ok? to apply? and not have to disclose it?

The short answer is that it all depends on the airline. for example:

Etihad/Oman Air/other M.E airlines - Ask you never have had a criminal record.
Virgin - Basic disclosure, and then require you to attend a security interview
BAA - Also say they do a basic criminal records check
Jet2 - require a 5 year criminal records check

etc

They all say that the offer of employment is subject to satisfactory criminal background checks - what one airline deems satisfactory might be different to another.

The long answer:

Once a conviction is spent it no longer needs to be declared when applying for most types of employment applications. However certain occupations are exempted from the provisions of the Rehabilitation of Offenders Act. Some violent offences would be relevant to positions involving unsupervised contact with the general public.

She will probably have trouble in the middle east - having been convicted of a serious offence. I have two friends with criminal convictions who have so far been unsuccessful in applying for cabin crew - one of whom was offered the job and then the offer was withdrawn by Emirates (drunk driving), BUT it doesn't necessarily mean an airline won't give her a shot.

Best advice I would give her is to check with all the the airlines before applying by give them a call and check. There's no point in going through everything that comes with applying for the job only to fall at the final hurdle.

Please do post any updates here as im sure this will be helpful to other people in the future :)

Good luck xx

Travelling or operating to the USA will be an issue as her record will be flagged up when she visits the US embassy for her Visa.

It doesn't mean she won't get a visa but if the record isn't declared, she definitely won't get a visa when the Embassy check her full record.

So what about drink driving then? A friend of mine had her offer withdrawn by BA because she had been collared for that. How much of an issue is that?

etihad specify in their requirements that cabin crew must never have committed a criminal offence. emirates does not. emirates at the moment are asking staff to sort out their own visa's for the US so she wouldn't have to apply for a visa and just choose not to fly there with work. Drink driving is a very serious offence in the UAE and that is probably why her offer was retracted as they could not risk one of their staff doing that while in Dubai.
Also if a conviction is spent the only country that can find that out is the USA all other countries that normally require visa's do not require them if you are cabin crew.
So as long as the conviction is spent i'm guessing she will be ok to appply. Also Emirates do not once ask on application or pre-joining form if you have ever committed an offence.

What about Ryanair? If it's didn't (more than 5years)