how to fly an ils approach
- The approach procedure may be flown using HDG SEL or LNAV for lateral tracking and VNAV, LVL CHG, or V/S for altitude changes. VNAV is the preferred descent mode when the FMS flight plan is programmed for the intended arrival. When VNAV is not available, use LVL CHG for altitude changes greater than 1,000 feet. For smaller altitude changes, V/S permits a more appropriate descent rate.
- When maneuvering to intercept the localizer, decelerate and extend flaps to 5. Attempt to be at flaps 5 and flaps 5 maneuver speed before localizer capture.
- APP mode should not be selected until:
- the ILS or GLS is tuned and identified
- the airplane is on an inbound intercept heading
- both localizer and glide slope pointers appear on the attitude display inthe proper position
- clearance for the approach has been received.
Note: The APP mode should be selected,both autopilots engaged in CMD, and the airplane stabilized on the localizer and glide path before descending below 800 feet RA.
At localizer capture, select the heading to match the inbound course. For normal localizer intercept angles, very little overshoot occurs. Bank angles up to 30° may be commanded during the capture maneuver. For large intercept angles some overshoot can be expected.
Use the map display to maintain awareness of distance to go to the final approach fix. When the glide slope pointer begins to move (glide slope alive), extend the landing gear, select flaps 15, and decrease the speed to flaps 15 speed.
At glide slope capture, observe the flight mode annunciations for correct modes. At this time, select landing flaps and VREF + 5 knots or VREF plus wind additive if landing manually, and do the Landing checklist. When using the autothrottle to touchdown, no additional wind additive is required to the final approach speed.
When established on the glide slope, set the missed approach altitude in the altitude window of the MCP. Extension of landing flaps at speeds in excess of flaps 15 speed may cause flap load relief activation and large thrust changes.
Check for correct crossing altitude and begin timing, if required, when crossing the final approach fix (FAF or OM).
If a false glide slope capture is suspected, perform a missed approach if visual conditions cannot be maintained.
INTERCEPTING THE GLIDE SLOPE FROM ABOVE
The following technique will help the crew intercept the G/S safely and establish stabilized approach criteria by 1,000 feet AFE
- select APP on the MCP and verify that the G/S is armed
- establish final landing configuration and set the MCP altitude no lower than 1,000 feet AFE
- select the V/S mode and set -1000 to -1500 fpm to achieve G/S capture and be stabilized for the approach by 1,000 feet AFE. Use of the VSD (as installed) or the green altitude range arc may assist in establishing the correct rate of descent.