DESIGN A DATABASE FOR AN AIRLINE INDUSTRY? that sounds ambitious.
Follow the standard procedures of course.
Go to the site,
collect requirements,
get it approved,
explain it to your developers,
develop a design document,
get it approved,
codify the design,
unit test it,
integrate,
test,
send it under the name test release,
collect complaints and bug reports,
explain most of them are what they wanted in the requirements,
fix the rest,
send a second test release,
hope to get lesser complaints,
wrap the project and present the final package,
sign off.