If the precision runway monitor/final monitor aid system is brought into play only in severe instrument flight rules conditions, the controller who is assigned as system operator has three entities with whom coordination is essential. The first is the pilot of an aircraft who commits a blunder on final approach and intrudes into the buffer zone between parallel runways. It seems likely that such a blunder will be symptomatic of other serious problems, so the controller might be well advised to minimize the time spent in coordinating efforts with this pilot. A second point of coordination is the pilot of the aircraft immediately adjacent to and affected by the blunder event. The effort made in reaching this person is crucial to the outcome of the episode. The third collaborator should be the arrival controller, who has responsibility for safe separation starting at the boundary of the terminal area up to the point of turn onto final approach. Ideally, a procedural arrangement would take place between the two controllers, so that aircraft would be metered onto the final approach in balanced numbers between the left and the right runways. Also important is the metering into the precision runway monitor/final monitor aid system such that sequence intervals are maintainable during the final approach.

To a somewhat lesser extent, coordination will also be needed with the tower controllers, who are responsible for separation and expeditious flow from runway to arrival gates. In effect, the precision runway monitor/final monitor aid system preempts some of the functions of the tower controller. Some review of the clearability of taxiways under instrument flight rules conditions should be done when the flow of landing airplanes is upgraded by the use of the precision runway monitor/final monitor aid. That is, the question arises as to whether surface control might not be overwhelmed in adverse weather conditions if the arrival rate is sustained at the higher level made possible by the precision runway monitor/final monitor aid.

Airborne Parallel Approach Monitoring

The organizational issues associated with the precision runway monitor are closely linked to an alternative plan for monitoring closely spaced parallel approaches via displays in the cockpit. This system, called airborne information for lateral spacing, has been under development at the National Aeronautics and Space Administration for the past few years and has a similar philosophy to that of the precision runway monitor. On the primary traffic display, the pilot will view his own approach and that of the parallel traffic. In the event of a deviation, or the prediction of penetration of the no-transgression zone, a graded series of alerts are presented in coordinated fashion between the two participating aircraft (the "intruder" and the "evader"). These involve first alerting the intruder, then

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