As long as your speech is clear enough to be understood by the average person to whom English is not native, accent doesn't matter at all. There are multiple accents in any language across its native country, let alone throughout the world. Well over 90% of the aviation people you will be working with will never raise an eyebrow about your accent, largely because it's a multicultural industry and they've heard everything, up to the point where they're already desensitised to it.