Offscale

The OFFSCALE message shows on the ND when an RA or TA is outside the current ND display area. The TFC switch on the EFIS control panel must be set to ON to show the OFFSCALE message. If an RA is outside the ND range, the OFFSCALE message shows in red. If a TA is outside the ND range, the OFFSCALE message shows in amber. If both a TA and RA are outside the ND range, the OFFSCALE message shows in red.

This message shows in these navigation display modes:

• Center (CTR) MAP* Expanded (EXP) MAP

• Expanded (EXP) VOR

• Expanded (EXP) APP.

Traffic

The red TRAFFIC message shows any time there is an RA. The amber TRAFFIC message shows any time there is a TA and no RA. The TRAFFIC message shows in all ND formats with the TFC switch on the EFIS control panel set to ON or OFF.

Ra and ta No-Bearing Traffic

The no-bearing RA and TA messages show on the ND when

TCAS loses the bearing of the RA or TA traffic. The bottom

directional antenna becomes an omnidirectional antenna when

the landing gear is down. When this happens, the bottom

antenna cannot find the bearing of the intruder traffic. The

bearing is NCD. Because of this, the no-bearing messages show on the ND.

If a TA becomes no-bearing traffic, an amber TA with the range, altitude, and vertical motion arrow shows on the ND. If an RA becomes no-bearing traffic, a red RA with the range, altitude, and vertical motion arrow shows on the ND. Only two nobearing traffics may show.

TCAS - ATTITUDE INDICATOR DISPLAY

General

These are the two types of TCAS vertical resolution advisories that can show on the attitude indicator (AI):

• TCAS RA - down advisory

• TCAS RA - up advisory.

These symbols only show for an RA when:

• The function selector on the ATC control panel is in the TA/

RA position

• The TCAS communicates with threat airplanes that give their altitude. Description

The red advisories show on the attitude display. They tell the flight crew to avoid some pitch movements.

The flight crew uses the advisories to avoid a possible collision with threat airplanes.

TCAS - AURAL MESSAGES

General

Aural advisory messages occur during these conditions:

• Traffic advisories (TA)

• Resolution advisories (RA)

• TCAS system tests.

Traffic Advisory Aural

When a traffic advisory occurs, the aural message TRAFFIC TRAFFIC comes on. This message tells the flight crew to monitor the display for intruder traffic.

Resolution Advisory

These are the two types of aural messages that can come on during a resolution advisory (RA):

• Preventive action RA

• Corrective action RA.

Preventive Action RA

This type of RA occurs when at the closest point of approach (CPA) the present vertical speed results in a safe altitude separation from the threat airplane. When this happens, the aural advisory is MONITOR VERTICAL SPEED - MONITOR VERTICAL SPEED. This message tells the flight crew to do these things:

• Maintain the flight path

Preventive Action RA

This type of RA occurs when at the closest point of approach (CPA) the present vertical speed results in a safe altitude separation from the threat airplane. When this happens, the aural advisory comes on.

These are the aural messages for the preventive action RA:

• MONITOR VERTICAL SPEED

• MAINTAIN VERTICAL SPEED, MAINTAIN

• MAINTAIN VERTICAL SPEED, CROSSSING MAINTAIN.

The preventive action RA messages tell the flight crew to do these things:

• Maintain the flight path

• Do not fly into the area of RA pitch symbol on the ADI

• Maintain the vertical speed rate.