Firstly what's the difference between an MSc and an MBA? An MSc (Master of Science) is a technical or scientific degree built normally upon a first degree in engineering or science. An MBA (Master of Business Administration) is a management degree built normally upon some years of management experience and/or a first degree.
Both normally take about a year full time, 2-3 years part time.
MBAs don't vary all that much, there is a basic core syllabus - although there are variants that specialise in particular industries.
MScs vary a great deal - the important thing is to pick the one that points you in the direction you want your career to take you. Many universities do excellent MScs in aeronautical disciplines, although Cranfield is certainly one of the best. For an aero-eng related MSc, a first degree in an engineering discipline, preferably at at-least a 2:2 grade, would be normal and preferable.
Avionics is a big and ever-growing discipline, and there are various MSc available - normally built upon a BEng or MEng in something like electronic engineering, aerospace systems engineering, or even aerospace engineering if you had enough electronics content in your options.
I've seen occasionally people do reasonable well on an aerospace MSc after a first degree in maths or physics, I've also seen somebody fail miserably after being unwisely allowed with a first degree in computer science - he just couldn't hack the mathematical content.
I can't honestly see anybody coping on an aerospace engineering MSc without something equivalent to a BEng in a mathematical or engineering discipline. This means one with a lot of calculus, engineering science, and report writing - and ideally an individual dissertation.
In some specialist engineering (design / analysis / testing, not usually maintenance) jobs an MSc is very helpful and employers may specifically seek people with the right MSc. More likely, it'll be used to differentiate between already strong candidates applying for such jobs.
Increasingly also, a lot of universities will require (or at-least much prefer) an MSc as a prerequisite to doing a PhD, which in turn is effectively the licence to conduct funded research in many environments. An MBA can be treated as a prerequisite for a PhD in management fields.
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