<p>Suppose you have a manager at Boeing overseeing the development of a new aircraft. He should know how the Boeing aircraft department works, how to schedule and lead project design reviews for this new aircraft, how to show off the company’s strengths to lure in contracts, how to sell ideas and products to Boeing’s aircraft customers, the aircraft department’s idiosyncrasies, etc. Basically, he oversees the entire project but doesn’t actually do all the detailed engineering work such as programming a chip or designing a circuit because that’s what the engineers do. To replace him, you would need someone who is an experienced aircraft engineer, who also knows all about the Boeing aircraft department and also knows how to deal with aircraft customers. </p>
<p>Even at a lower level of management, say the flight test manager. He needs to know how to negotiate with the government and other agencies to schedule dates, the method to direct engineers to ensure a successful flight tests, how to deal with regulations and safety issues, how to deal with internal and external political issues and pressures if a flight test should fail.</p>
<p>However, to replace an super-smart senior VLSI lead engineer, the person in charge of all the VLSI design for an aircraft, you can probably hire another VLSI genius from another company like Lockheed, and he can pick up on the task after a short period of time by following the design notebooks. The only type of irreplaceable engineer is someone working on something so cutting-edge that no other expert in the field knows about. I believe these types of engineers tend to work at research places like Bell Labs or Lincoln Labs.</p>