Milestone (aircraft)

There are several important milestones in the development of aircraft. Some of these include:

Program launch
First order
Prototype model: One or Small number of aircraft built to validate soundness of design before commitment to production models with a finalized design.
Roll out: Aircraft is complete, nearly complete, or complete enough to roll out of the factory.
First flight: Normally occurs within months of roll out
Certification (civilian): Approved for service by FAA or aviation regulators
Production model: Finalized design, incorporating modifications needed as determined by tests of prototype or changes in specifications. Sometimes the production model phase is skipped to save time, but this can lead to producing large numbers of unusuable aircraft if the prototype proves unsuitable, as in the case of the F-102 Delta Dagger which was not supersonic in its original form. 21 unflyable F3H Demons were produced after all aircraft were grounded because of problems with the failed J40 engine.

Not all programs reach these milestones. Some aircraft are cancelled before production, some do not fly, some are not put into production.

Also see