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Home > Flying on the Boeing 777 > How does a pilot execute an auto landing during bad weather in a Boeing 777?
How does a pilot execute an auto landing during bad weather in a Boeing 777?
Flying - Flying on the Boeing 777
Tuesday, 11 December 2007 20:49

Hi Capt Lim,

You have a great website with lots of information on the Boeing 777. Keep it up!

I wanted to know whether a Boeing 777 could land on autopilot? If so, how does the pilot auto land the airplane?

Thanks a lot,

Best Regards,

Arjun,
Durban, South Africa

Hi Arjun,

I have received a lot of emails, especially from those who fly the Microsoft Flight Simulator 2002, requesting to know, how a Boeing 777 performs an auto landing. Most of them were under the impression that it looks uncomplicated because of computers guiding it all the way to a safe landing. For the benefit of the many inquisitive visitors, I will now run through the whole procedures briefly.

Sure, a Boeing 777 is capable of landing very safely on autopilot even in zero visibility but it is not currently authorized. Why? The cost of maintaining the ground equipment is prohibitive and so the authorities reduced the criteria from zero visibility to 100 meters as the absolute minimum to land at the present time. These lower criteria also reduce the maintenance costs as imposed by the aviation authorities. This would have opened many Airports that would otherwise be shut down.

The Instrument Landing System (ILS) provides a very accurate and safe guidance for an airplane to land on a runway in any weather conditions. It positions the airplane very precisely to land safely in the most adverse situations where a pilot would have great difficulty doing so. Bearing in mind that, about 75 percent of accidents are due to human errors and the landing phase is one of the most critical parts of a flight, air crashes have been reduced considerably when the ILS was introduced. An ILS can be flown manually or by coupling it to an autopilot, or to put it simply, let the computers fly the plane! Humans can never beat a machine and so, if a pilot wishes to manually fly the ILS to hone his flying skills, he is restricted to fly to a minimum of 200 feet above ground level and a visibility of 550 meters. Beyond that, he must seek the help of the machine! In other words, the airplane must be auto landed with the help of computers.

What happens when the computers fail at the critical moment? So, you still need human beings to save the day! Pilots are the back ups to machines. Hence, aircrew must undergo a thorough course in order to perform this task.

An auto landing process is achieved by an autopilot together with a flight director system. As the name suggests, the flight director directs where the plane go when the pilot or autopilot intend it to. To fly an ILS, the flight director would guide the airplane to land on a correct profile and towards the centerline of the runway by means of ground signals. In order to land safely, the airplane requires external feedbacks from the aerodrome.

Now we have a good Boeing 777 with auto landing capability, a qualified and competent pilot and the third link must now be excellent aerodrome facilities. Indeed, the maintenance of the aerodrome must be very high and comply with ICAO standards. What happens when the airplane is locked onto the signals on final landing in fog and there was a power failure on the ground? ICAO requires the back-up power with switchover time be not more than one second for all the critical electrical lightings.

Prior to an auto landing procedure, the Captain would give his copilot a very thorough briefing from how many minutes he has left before he commences a diversion to the procedures on what action to take if a pilot suffers a heart attack prior to landing. So every emergency is covered and nothing is left unprepared.

Assuming the Boeing 777 has now captured or locked onto the ILS at 2500 feet, the copilot would call out various stipulated heights to remind each other of the progress of the approach. The callouts would be at 2000, 1500, 1000, 500, 200 or (alert height) and decision height of 20 feet. The Captain must respond to all height checks and there are pre-planned actions, for instance when some responses are not forthcoming. If the Captain does not respond to a callout of the height-checks from 500 to 200 feet, the copilot would assume that his Captain has lost consciousness due to a heart attack or any incapacitation, then take over control and abort the landing. Why is it so? He is too close to the ground to find out! Ask questions later when he has safely aborted the landing! He is fully competent to do so because the copilot is checked every six month on this drill.

The auto landing procedure is executed automatically but the Captain still have to intervene to reduce speeds as the flaps are selected from 0, 1, 5, 20 and then to 30. At any time an emergency crops up, each pilot knows what to do because they have been covered during the briefing. Below 200 feet above ground level, the computers would ignore non-critical emergencies because pilots should not be disturbed at this very crucial phase of the landing.

At 50 feet, the autopilot flares the airplane, a term to describe how it would raise the nose slightly to prepare for a soft landing. The computer would call out aurally the heights every 10 feet and then at around 25 feet, the throttles are closed. At this point, the airplane should sit onto the runway gently and roll along the centerline until it comes to a complete stop by the auto brakes with the pilot aiding it further with reverse thrusts. You are now safely landed! If the Captain is unable to see the taxiway because the visibility has further reduced, he may request a ‘Follow Me’ vehicle to guide the pilot to its parking bay.

Have a safe and pleasant auto-landed flight soon

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difference between ILS heading and Course
Hi capt.Lim,
I dont know if someone has already asked this question(I tried to find it but i couldn't), that what is the difference between ILS heading and course. Secondly I want to ask you that, someone told me that in B777, when ILS auto landing is done the weather forecast is also entered in the computer which helps it during cross wind landings. Is it possible in FS?
Sami , 19 Sep, 2010
how important is runway lighting to land a plane in night
Sir,
Please can i know how important is runway lighting to land a plane in night
james , 06 Nov, 2011

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