(b)
Two minutes before reaching waypoint 1, the ALERT light will illuminate. One-half minute before reaching waypoint 1, the FROM-TO display will automatically advance from 0-1 to 1-2, the ALERT light will extinguish, and the system will navigate to waypoint 2 along the 1-to-2 track leg. The system will continue to automatically navigate to consecutive waypoints.
(9) Manual Operation
(a) When it is desired to make a manual track change, the AUTO/MAN/RMT switch is placed to MAN. The INS will continue to navigate with respect to whatever track was established on the FROM-TO indicator. Two minutes before arrival at the TO waypoint, the ALERT lamp will illuminate indicating that the pilot should set up the track change. Next the TK CHG pushbutton is depressed, which causes the FROM-TO display to extinguish and the TK CHG INSERT pushbutton to illuminate. The next track leg is then selected from the keyboard by pushing first the FROM waypoint number, then the TO waypoint number. The new numbers will show immediately on the FROM-TO indicator; however, navigation is still with respect to the old track leg. To initiate steering with respect to the new track leg, the INSERT pushbutton is depressed. This can be done anytime before or after crossing the old TO waypoint, which normally would be the new FROM waypoint. However, 0.5 minute before reaching the old TO waypoint, the ALERT lamp will begin to blink, indicating that this is the time where steering with respect to the new track leg would have occurred in the automatic mode. The ALERT light is inhibited at ground speeds (GS) of less than 250 knots.
EFFECTIVITY AIRPLANES WITH LTN-72 INS
CONFIG 01 A Page 46 Aug 25/87
34-41-00
WHEN STATUS 02 STARTS, MSU READY NAV ANNUNCIATOR COMES ON IF MODE SELECTOR SWITCH IS SET TO ALIGN. WHEN STATUS 02 STARTS, INU AUTOMATICALLY GOES INTO NAV MODE IF SWITCH IS SET TO NAV (READY NAV ANNUNCIATOR DOES NOT COME ON) AND 14 MIN. 5 SEC HAVE ELAPSED SINCE END OF
ALIGNMENT TIME IN MIN
STATUS BECOMES 01 WHEN INU ENTERS NAVIGATE MODE EITHER AUTOMATICALLY OR WHEN MSU MODE SELECTOR SWITCH IS SET FROM ALIGN TO NAV AFTER READY NAV ANNUNCIATOR COMES ON
INS Alignment Sequence
Figure 18
EFFECTIVITY
CONFIG 2
AIRPLANES WITH LTN-72INS
799 Page 47
34-41-00
Aug 25/86
(b)
Steering to any waypoint with respect to aircraft present position can be initiated at any time. The procedure is identical to manually changing track except that the 0 is selected as the FROM waypoint as in the case of the initial track leg. First the TK CHG pushbutton is depressed; then 0 is selected from the keyboard as the FROM waypoint; then the TO waypoint number is selected; and finally the INSERT pushbutton is depressed to initiate steering to the new TO waypoint. The present position at the time the INSERT pushbutton is depressed becomes the coordinates of the 0 waypoint.
(c)
If an error is made in selecting the FROM-TO waypoint numbers, it can be cleared in the same manner as when loading waypoint data. If the error is made before the INSERT pushbutton is depressed, depress the CLEAR pushbutton and reload the waypoint numbers. If the error is noticed after the INSERT pushbutton was depressed, depress the TK CHG pushbutton and reload the waypoint numbers.
(d)
Should the operator decide not to make a waypoint change after having depressed the TK CHG pushbutton, simply depress it a second time and it will extinguish. The previous track leg will reappear on the FROM-TO indicator.
(e)
To reinitiate automatic track selection the AUTO/MAN/RMT switch is placed at AUTO, and the system will revert to automatic operation. At the next automatic track change the system will select the next highest waypoint number.
(10)
Desired Track Hold
(a)
The pilot can initiate an INS track hold mode of operation, allowing him to fly from his present position off-track on autopilot, on a track referenced to true north rather than on a track between waypoints.
(b)
To insert a desired track angle, place the display selector switch in the DSR TK/STS position and select MAN on the AUTO/MAN/RMT switch. Next 0 is selected from the keyboard causing the INSERT pushbutton to illuminate, then the desired track angle is selected from the keyboard. The number will appear on the left display. Navigation with respect to the new desired track will occur when the INSERT pushbutton is depressed. The FROM/TO display will indicate 9-9.
(c)
To return to a waypoint-to-waypoint mode of operation, manually initiate a normal track leg change from present position.
(11)
Waypoint Bypassing
(a) The pilot can bypass waypoints in one of two ways; by initiating either a track leg change at waypoint or a track leg change from present position.
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