Wednesday, April 7, 2010


Sometimes, the weather at the destination airports not always good. During winter the visibility can be as low as 100 meters only in fog, especially in the early morning. At this visibility the runway will not be visible until the plane is just a few feet over the runway. As an airliner, we can't just divert to more suitable airport for landing as that actions will cost the company a lot of money. The modern aeroplanes are now equipped with automatic landing capability whereby the pilots do not have to see the runway for landing even though the visibility is at zero !! It is fully automatic, the pilots job is just to monitor the flight path, the systems working normally and to take over manually in the case of any abnormalities occurred. Take over mean not necessary to land the plane, it could be to bring the plane up again and land somewhere else which has a better weather for safe landing visually.

In order to carry out the approach, the flight computer must be programmed to follow the standard published procedure as per the chart below. This eg is for the arrival into Geneva Airport, following the BANKO TWO ROMEO arrival for runway 23. Once programmed, the autopilot will fly the plane according to the route in the chart, starting from BANKO (which is just a few miles from Mont Blanc ) following the track and the vertical path accurately.

Then the plane will intercept the final approach path, which is 3 deg descend angle towards the runway 23 as per the Instrument Landing System (ILS) chart below, following the exact track and vertical path. On the lower side of the chart, the vertical profile is shown, which the distance and the height the plane should be.

The pilot should be scanning the Primary Flight Display (PFD) , letting the plane fly by itself, just standby to take over in case any malfunction occurs. CAT3 DUAL mean the airplane will land by itself and the pilot will take over when safely on the ground .
ps : This PFD picture is just a sample as it does not show the approach for ILS runway 23.

Normally the pilot will take over to stop the plane or to taxi to the parking bay if the taxiway is visible. Minimum visibility to taxi the plane is 30 meters. Airport chart must be read before coming to land so that the pilot will be familiar with the layout and the parking bay, to avoid getting lost on ground.