Aircraft traffic alert and collision avoidance system with autoflight system mode protection

An autopilot-coupled traffic alert and collision avoidance system (AP TCAS) configured to be implemented on an aircraft, the AP TCAS comprising:

• a flight control system that is configured to provide a first and a second aircraft vertical speed setting;
• an autopilot (AP) system that is configured to automatically cause the aircraft to fly at a vertical speed in accordance with the first vertical speed setting;
• a traffic alert and collision avoidance system (TCAS) that senses a range, bearing, and relative altitude of an intruder aircraft, and, based on the sensed range, bearing, and relative altitude, is configured to issue a preventative resolution advisory (RA) that indicates a maximum vertical speed the aircraft should not exceed in order to avoid a conflict with the intruder aircraft;
• and
• an AP/automatic flight control system (AFCS) that is configured to receive the second aircraft vertical speed setting after the TCAS issues the preventive RA, wherein the second aircraft vertical speed setting exceeds the maximum TCAS vertical speed, the AP/AFCS being further configured to:
• 1) modify the second aircraft vertical speed setting so as to be less than the maximum vertical speed, and relay the modified second aircraft vertical speed to the AP/AFCS system to automatically cause the aircraft to fly at a vertical speed in accordance with the modified second vertical speed setting;
• and
• 2) relay a command to the AP/AFCS system to initiate an automatic, corrective flight maneuver if a current vertical speed of the aircraft is within a predetermined amount of the maximum vertical speed or exceeds the maximum vertical speed, or is predicted to enter the vertical speed limit at some future time based on a prediction algorithm.