Shenzhen From United States of America, joined Jun 2003, 1717 posts, RR: 2
Reply 4, posted (11 years 3 months 4 weeks 11 hours ago) and read 2013 times:
Each airline has additional procedures that they may want to include in their operational manuals. The manufacturer's manual may have 5 steps to start an engine, whilst the airline may have 7.
For an example, an airline may experience somthing that the industry hasn't. In this instance, the manufacture may not want to change the manaul for everyone, but the airline feels they require some additional steps to ensure they don't experience it again.