(Presented by R. Hanson, United States)

This paper lists numerous questions raised relative to the mandating of TCAS in Caribbean airspace and Flight Standards responses to these questions.

1. INTRODUCTION

The use of TCAS or ACAS has long been a controversial issue. From its inception their have been those that have doubted its worth. When it was first introduced, pilots disliked it because of potential false resolution alerts. Today, however, most pilots wonder how they ever got along without it. Gradually the knowledge of the importance of TCAS has spread world wide and more and more emphasis has been placed on mandating its use. It's use is currently a high priority agenda item with several ICAO panels and was entered into ICAO Annex 6, Part 1 effective November 5^th, 1998. Incidents such as the recent near mid-air collision between two cargo carriers, a mid-air collision between a German military aircraft and a US C-141 in 1997 and incidents in the North Atlantic all point to the need for a universal acceptance of a TCAS equipage. TCAS often provides the only means of protection against inevitable blunder errors such as those that have occurred in the NAT.

Implementation of reduced separation requires that Flight Standards evaluate Communication, Navigation, and Surveillance criteria before approval of the reduction is granted. The surveillance capability guards against blunder errors and is usually accomplished by radar or ADS. In the absence of these surveillance tools, the only other means available to guard against blunder errors is TCAS.

There are, however, questions that arise relative to the mandating of TCAS and the purpose of this paper is to state those questions and to provide Flight Standards responses.

2. QUESTIONS AND ANSWERS

Q1: At what lateral separation reduction does Flight Standards require TCAS to be mandated?

A1: Separation was reduced in the Pacific Rim from 100 nm lateral separation to 50 nm lateral separation without TCAS being mandated. However, aircraft navigation performance and safety are monitored against a Target Level of Safety which places a limit on the number of large navigation errors that can be tolerated. Thirty lateral-thirty longitudinal (30/30) separation has the following proposed requirements: Communications - DCPC; Navigation - RNP-4, and Surveillance - ADS-A. These reductions both incorporate safeguards against blunder errors.

Q2: If TCAS is required for 10 nm route spacing with no radar surveillance in the Gulf of Mexico and/or Caribbean waters, is this policy consistent with domestic policy over the continental United States?

A2: No. ATC currently utilizes a policy that has separation revert to an oceanic separation standard when radar is lost. The T-Routes are a special situation in which Flight Standards has been asked to approve a reduction in separation from oceanic criteria down to 10 nm between centerlines under non-radar conditions. Although domestic standard have been applied to Class A offshore airspace, the operational environment has not changed and thus a safeguard is required to protect against blunder errors in areas in which lateral separation has been significantly reduced.

Q3: Can a controller clear an aircraft without TCAS (if Radar is inoperable) on unoccupied routes?

A3: Yes. It is controller discretion to use another form of separation. If a controller has a vacant route/altitude that he/she wants to use for a non-equipped aircraft, this is acceptable if the separation with other aircraft is consistent with ICAO criteria for international waters.

Q4: Will dead reckoning still be allowed in the Gulf of Mexico if a reduction in lateral separation is implemented?

A4: No, in fact, there are numerous regulations currently in place that state the navigation requirements for extended overwater operations. These Title 14 Code of Federal Regulations are:

All of these regulations require at least a single long range navigation system for extended overwater operations in the Gulf of Mexico.

Q5: Will Military aircraft without TCAS be allowed to operate on T-Routes and other routes in which lateral separation is reduced to 10 nm?

A5: Although there is a great deal of concern in Flight Standards relative to non-TCAS equipped aircraft, Flight Standards is prepared to discuss possible alternatives with the military. It is noteworthy that the first collision in the enroute environment in 35 years was between two non-TCAS equipped military aircraft.

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