VII. Choose the best completion of the sentences

1. Large aircraft often had a third crew member, the flight engineer, …

a) whose duties were to operate engines and aircraft subsystems.

b) those navigators were trained in celestial observatories to take fixes and compute position.

2. The navigator's crew station disappeared in civil aircraft in the 1970s, …

a) despite airborne digital computers became available in the 1960s.

b) because inertial and radio equipment calculated position and accommodated failures.

3. Various promising techniques in this area had been evaluated since the mid-1960s, …

a) while the civil mode could achieve 40-meter accuracy

b) but each was disqualified for different reasons.

4. A major challenge facing the avionics industry and the military will be to define …

a) how aging avionics systems can be kept up-to-date, operational and supportable.

b) the biggest change in the commercial-avionics industry since the move to digital technology is under way.

5. The focus of this project lies on safety, …

a) as integration holds the key to realizing the promised economic and operational benefits.

b) but this system also has benefits in the maintenance of the airplane.

6. After more than 50 years of satellites in operation, …

a) GNSS is becoming an increasingly critical part of the public infrastructure.

b) space has become a normal part of our daily life.

7. … a smaller number of even more skilled engineers were employed to design the automated systems.

a) Instead of requiring a skilled navigator on each aircraft,

b) So that subsystem management and navigation can be done by one or two pilots