FAA Aircraft Dispatcher (ADX)Navigation and ATCMedium
ATC is conducting simultaneous independent ILS approaches to two parallel runways in IMC. What minimum runway centerline separation is generally required for this type of operation, along with monitoring of a No Transgression Zone (NTZ)?
- A5,000 feet
- B2,500 feet
- C3,000 feet
- D4,300 feet
Show answer & explanationAnswer & explanation
Correct answer: D. 4,300 feet
Simultaneous independent ILS approaches to parallel runways generally require at least 4,300 feet of runway centerline separation, with a designated No Transgression Zone (NTZ) monitored by radar to ensure separation is maintained if an aircraft deviates from its final approach course.
Why the other options are wrong
- A. 5,000 feet exceeds the typical requirement, though wider spacing may allow reduced monitoring.
- B. 2,500 feet is too narrow for independent operations without additional precision monitoring systems.
- C. 3,000 feet does not meet the standard independent approach spacing requirement.
Simultaneous Independent Parallel ILS Approaches
A procedure allowing independent radar-monitored ILS approaches to closely spaced parallel runways, requiring at least 4,300 ft centerline separation and use of an NTZ.
- Minimum 4,300 ft runway centerline spacing (standard case)
- No Transgression Zone (NTZ) monitored by radar between final approach courses
- Requires precision runway monitor for closer spacing in some cases
Memory trick: '4,300 feet — the safety gap between two jets landing side by side.'