Aerospace Engineering

As an Aerospace Engineer, it is utmost crucial to decide your interest whether you would be interested in Aeronautical Engineering or Astronautical Engineering. Both the branches have excellent job opportunities.
Job opportunities for these engineers are available in Airlines, Air Force, Corporate Research Companies, Defence Ministry, Helicopter Companies, Aviation Companies, NASA and many others.
Increasing popularity of air travel and space exploration require expertise to design and maintain improvements. Looking at heightening growth rate, the demand for smart and create Aerospace Engineers is only going to increase in the near future.
Some of the top recruiters in this space are Hindustan Aeronautics Limited (HAL), Defense Research and Development Laboratories (DRDO), Indian Space Research Organization (ISRO), Civil Aviation Department, Air India, India Space Research Organization (ISRO) and others.

General Software
1) Familiarity with different operating systems (Windows, Mac, Linus, Unix, etc.)
2)Microsoft Office and document processing (Word, Excel, Powerpoint) since as engineers we have to be able to communicate our work to others.
3)Matlabis a common programming tool used for engineers, although C+ and Fortran has it's applications as well. I.e. I know CFD codes use Fortran a lot since it compiles code it executes large data sets much quicker.
4)CAD Software. The most common are Solidworks, Unigraphics, ProEngineer, Catia, AutoCad, and there are many others. If you create things, CAD is a necessity. Different companies have preferences on CAD software however file compatibility is continuously improving.
Experiments
5)National Instruments LabVIEWis a standard for experimentalists these days. It allows easy interfacing between hardware and software so that you can acquire data, control experiments, and process/analyze data. It is graphical based programming (which I find very intuitive and easy to learn).
Computations
6)FLUENT, OpenFOAM, ANSYS,etc. Depending on what you are working on and if you have access to commercial software. Here is a good list of software for FEAList of finite element software packages
Graduate Student
7) Latex. This is an open source document processing software which has a steep learning curve but once learned, it makes writing a thesis or dissertation much easier and higher quality. LaTeX - A document preparation system or LaTeX
You will undoubtedly learn many specialized software packages throughout your career, especially since software is inundating every aspect of our lives and work these days. For example, I have also learned video editing software, specialized software for processing data acquired with a specialized measurement tool (Davis - for processing PIV data), web programming software (html and CSS), and more.
Let your education and career guide you, but always keep an open mind to learning new software, you'll be surprised at when certain skills come in handy!

Hello Himanshu,
As an Aerospace Engineer, it is utmost crucial to decide your interest whether you would be interested in Aeronautical Engineering or Astronautical Engineering. Both the branches have excellent job opportunities.
Job opportunities for these engineers are available in Airlines, Air Force, Corporate Research Companies, Defence Ministry, Helicopter Companies, Aviation Companies, NASA and many others.
Increasing popularity of air travel and space exploration require expertise to design and maintain improvements. Looking at heightening growth rate, the demand for smart and create Aerospace Engineers is only going to increase in the near future.

Hello,
Pursuing Aerospace Engineering as a specialization in Post Graduation (M.Tech) is indeed a better choice. Aerospace Engineering is a niche branch in India with limited job opportunities at present. However, since you already have completed Bachelors in Mechanical degree, you can apply for jobs in mechanical sector, whilst you can also keep looking for jobs in your desired role in Aerospace Engineering. This way, your career won't halt. While, your job in mechanical domain will keep earning you experience, you can choose your path in the Aerospace domain whenever you get a good opportunity.
I hope this answers your question to your satisfaction. If you have any further questions, kindly revert.