VNAV Target Altitude Capture is analogous to Selected Altitude Capture Mode and is armed automatically after the VNAV Key is pressed on the AFCS Mode Controller or the VNAV Button it touched in the AFCS Control window on the PFW, if the VNAV Target Altitude is to be intercepted before the Selected Altitude. The annunciation ‘ALTV’ indicates the VNAV Target Altitude is to be captured.

As the aircraft nears the VNAV Target Altitude, AFCS automatically transitions to VNAV Target Altitude Capture Mode with Altitude Hold Mode armed. This automatic transition is indicated by the green ‘ALTV’ annunciation flashing for up to 10 seconds and the appearance of the white ‘ALT’ annunciation.

At 50 feet from the VNAV Target Altitude, the AFCS automatically transitions from VNAV Target Altitude Capture to Altitude Hold Mode and selects the VNAV target altitude as the new Autopilot Altitude Reference. As Altitude Hold Mode becomes active, the white ‘ALT’ annunciation moves to the active vertical mode field and flashes green for 10 seconds to indicate the automatic transition.

A VNAV Target Altitude can be specified in several different ways, which result in different system behavior depending on whether the airplane is climbing or descending (as shown in the following table).

Table 57: VNAV Target Altitude Behavior

VNAV Target Altitude Type	VNAV Target Altitude Indication	Climb Behavior	Descent Behavior
At		Arms ALTV	Arms ALTV
At-or-Below		Arms ALTV	Does not arm ALTV1, 2
At-or-Above		Does not arm ALTV1	Arms ALTV
Between		Arms ALTV using the upper altitude	Arms ALTV using the lower altitude
1 Even if ALTV Mode is not armed, the ‘UNABLE VNAV ALTITUDE’ system message will be shown if the airplane’s vertical speed is not sufficient to meet the targeted altitude before crossing the waypoint.
2 Normally, AT-or-BELOW altitudes are not used to define a BOD. However, if an AT-or-BELOW altitude is used in this way, it will be treated as an AT altitude (arming ALTV Mode). Intermediate AT-or-BELOW altitudes in the descent do not arm ALTV.