Chapter 9 - Automatic Landing System

Question 1

What is the minimum reliability value for an automatic landing system?

Answer 1

1 in 10⁷

Question 2

What does autoland command when 1500 feet radio altitude is reached?

Answer 2

• Capture of the localiser and the glideslope beams
• Remaining armed flight control changes to be automatically engaged
• Computerised landing flare control to be armed

Question 3

What does autoland command when 330 feet radio altitude is reached?

Answer 3

• Trimming the aircraft to a nose-up attitude
• Elevators to be deflected to counter the trim

Question 4

What does autoland command when 45 feet radio altitude is reached?

Answer 4

• Flare mode to be automatically engaged
• Throttle retard to be engaged to match the landing flare path

Question 5

What is the descent rate when in flare mode?

Answer 5

2 feet/second

Question 6

What does autoland command when 5 feet radio altitude is reached?

Answer 6

• Flare mode to be disengaged
• Transition to the touchdown and rollout mode
• Pitch attitude to be reduced to 2° at about 1 ft radio altitude

Question 7

What does autoland command at touchdown?

Answer 7

• Lower the aircraft’s nose and bring the nosewheel into contact with the runway
• A/T system is automatically disengaged when reverse thrust is engaged

Question 8

To what speed should the forward speed of contact have been reduced to?

Answer 8

About half of the approach margin of V_S 1.3 (30%) above stall

Question 9

What are the decision heights for the various categories of landing?

Answer 9

Category 1 - Above 200 feet

Category 2 - Between 100 and 200 feet

Category 3 - Down to 0 feet

Question 10

What is a fail-passive automatic landing system?

Answer 10

In the event of failure, there is no significant out-of-trim condition or deviation of flight path or attitude but the landing is not completed successfully

Question 11

How many autopilot systems are required for fail-passive automatic landing system?

Answer 11

Two APs

Question 12

What is a fail-operational automatic landing system?

Answer 12

In the event of a failure, the approach, flare and landing can be completed by the remaining part of the automatic system

Question 13

How many autopilots systems are required for fail-operational automatic landing system?

Answer 13

Three APs

Question 14

What does an autoland require if decision height is at zero and there is no runway visual range (RVR) limit?

Answer 14

Ground roll system which is fail-operational

Question 15

When can A/T not be required for autoland functions?

Answer 15

• Decision height is 15m or greater; and
• Speed can be controlled manually by the crew within acceptable limits and without excessive workload