[Jeeper1941]

What an awesome thread! So much information!

I'm a huge T7 fan, and have flown it at least 20 times, mostly the SYD-LAX route. Also going to do the Emirates AKL-DXB route in September, looking forward to that epic flight!

One more thing - every aviation (especially Boeing) fan needs to take the Boeing factory tour - it is just so amazing to see these things actually being built. What incredible machines.

[searchingheaven]

Originally Posted by honeybee

Also in order to be able to land successfully do you guys need to train for it? Are there any additional certifications to acquire before a pilot can fly to such airports, or is it part of the basic training?

Just out of sheer curiousity, what is most likely to fail during a landing? I am assuming take offs are relatively safer than landings with a lesser number of things likely to go wrong, whereas during landing, the chances of various things going wrong would be higher. So out of all components required to make a safe landing, what are the things more likely to fail - maybe in terms of previous statistics? And what is the most critical part that MUST work for a safe landing?

A lot of questions, my friend. But I will try to answer them.

Crosswind landings do not require any extra certification for pilots. But yes, we do train for it extensively. As far as part failure is concerned, we follow murphy's rule. Anything that can go wrong will go wrong. So the idea is to monitor the three basic parameters of flying - airspeed, altitude and attitude. If you maintain these three parameters, you will most likely be safe. There is no critical part I can name which must work. Although there exists a MEL(minimum equipment list) which must be satisfied before an aircraft takes off.

Originally Posted by souvik6

Excellent thread with tons of first hand info from professionals and enthusiasts! Do check it out as it is supposedly one of the most exciting and favorite maneuver of pilots.

Thanks for the compliments, Souvik.

Youtube makes crosswind landings look dramatic, but they're not really dangerous. First off, aircrafts have crosswind (component) limits that are a function of the geometry of the wind-runway angle and speed. They can actually handle a greater crosswind than that limit but the limit gives a safety margin for pilot proficiency level and just plain luck. If the wind exceeds the limit, you go-around. But if it's under the limit, the landings aren't unlike normal landings. Sure you have to de-crab or side-slip, but it looks harder than it usually is. Most pilots don't have issues dealing with it.

The B777's cross-wind limit is 38kts and the autoland limits are 25 kts. headwind, 25 kts. tailwind and 15 kts cross-wind.

Originally Posted by Jeroen

I assume you are referring to Asiana 214 at Los Angeles? In addition to the captain not having much hand flown lately, there was also confusion/misunderstanding on the flightdeck on what was to be expected from changing the vertical mode to FLCH SPD. (see our earlier discussion about vertical modes)


Jeroen

Originally Posted by coolboy007

The problem these days is that there is so much automation that pilots are forgetting to fly manually and how to handle the aircraft when the auto pilot trips off. There was an accident recently in US with a 777 doing an ILS approach, the glide slope at airport was inoperative providing vertical guidance and only localizer was working (lateral guidance), the crew was informed about it but the aircraft crashed. The commander later said that he had not hand flown an approach without vertical guidance for so long that it became impossible for him to do it.

Your first point is valid and I have highlighted the same issue in my previous posts. But OZ214 could've been avoided with proper training and knowledge. Our operator's unwritten rule is that you should know the FCTM by heart.

Now let's look at the chain of events that happened before the crash.

1. OZ214 was cleared for a visual approach. The missed approach altitude of 3000 ft was set in the MCP.
   
2. During the approach phase the aircraft descended below 3000 ft since the pilots had used V/S to descend.
   
3. When the pilots noticed that they were below the ideal altitude, the pressed FLCH. The aircraft naturally started to climb to the 3000 feet MA altitude they had dialed in.
   
4. So they disconnected the autopilot and the manually moved throttles to idle to reduce the thrust.
   
5. But the A/T was still armed. When the throttles were moved to idle, the A/T went into HOLD mode, in which it does not command speed.
   
6. By the time they realized this, they were too late.

So it is very clear that they didn't know the proper functionality of FLCH and the ATHR modes. Our operator is doing OZ214 as a case study and our instructors have drilled this in our heads - learn the manual.

Originally Posted by Jeeper1941

What an awesome thread! So much information!

Thanks for the compliments.

[Jeroen]

Originally Posted by honeybee

What are the airports or places where you see such high crosswinds? Mind you, these aren't small airplanes like the Cessna, but sometimes big jets too. Also in order to be able to land successfully do you guys need to train for it? Are there any additional certifications to acquire before a pilot can fly to such airports, or is it part of the basic training?

Just out of sheer curiousity, what is most likely to fail during a landing?

A lot of clarification already from the Pro's. Let me add my 2-cents worth from a Private Pilot (somebody who flies Cessna's and such) point of view

You can experience crosswinds just about anywhere in the world. Schiphol Amsterdam is the world lowest international airport (below sea level!) and you can find some spectacular Amsterdam Schiphol cross wind landing on YouTube as well.

But Schiphol has multiple runways and they can minimise crosswind by altering which runway to use. And they do. But there are plenty of (international) airports who might have only one or two runways. They would be built to line up with prevailing winds, but of course wind direction does change now and then.

As far as I know commercial jets are certified to land up to a certain crosswind component. So pilots will not go beyond that.

My little planes aren't. They have a so called demonstrated maximum cross wind component. Which means, I can, at least from a legal point of view, land with higher cross winds. Whether that is very smart is a different matter altogether.

The commercial jets can handle a lot more crosswind then the little planes.

Every pilots start by obtaining hir/her PPl (Private Pilot License) and dealing with crosswinds is a mandatory requirement. It part of your check ride prior to getting your pilot licence. My experience is you need to do it a lot and you need to keep doing it a lot to stay current (not from a legal point of view, but from a stick and rudder feel point of view).

My flight instructor was very vocal about cross wind technique. He always called it a proper end of any flight and a potential life safer if thing turn sour.

The more cross wind you can handle confidently the more airports are available to you in case of an emergency. Say I'm out there flying my little one engine plane and the engine starts to run rough. You just want to land as soon as possible. The more runways and their respective crosswind are available to you, the more option are open to you. I used to fly based out of Kansas City. In Kansas and Missouri prevailing winds are North- South direction. So there are hundreds and hundreds of airports with N-S runways. But on those days that the wind comes from a different direction you will have to deal with crosswind, no matter what. There might not be a runway for hundreds of miles with little or no crosswind.

The big commercial jets can all (?) land fully automatic with substantial crosswinds too!


If I had to make a call on what is the most likely thing to fail during a landing I would say, the pilot not going around when they should have. Every plane needs to be stable somewhere say 500-1000 feet of the threshold. Stable means you are in landing configuration (gear down, flaps down) you are lined up correctly, and you are descending appropriately in a steady manner. If not, you go around. If you don't feel entirely happy, you go around. If you experience a huge itch on your bum, you go around. Etc. going around is a safety manoevre. It ensures you dont get yourself into a tricky situation. You dont have to explain yourself to anybody, once you are estalished in the climb you tell the tower. They wont question you.

I know some commercial carriers require their pilots to report on go arounds and depending on what they do with that information it could be questionable. Nothing should prevent a pilot from going around. Anything that holds him/her back is a concern I would say.

Both commercial and private pilots have an unfortunate reputation of not going around when they should.

Having said that, to earlier comments, commercial aviation is of course, extremely safe. Even those horrible accidents we do see every year are near insignificant from a statistical point of view. Of course, utterly devastating for those who are on those flights, their friend and relatives.


Jeroen

[honeybee]

Based on historical evidence, which was the part or component that failed the maximum times during landing? Was my question.

[Jeroen]

Originally Posted by honeybee

Based on historical evidence, which was the part or component that failed the maximum times during landing? Was my question.

No idea, but in general parts failing to the extent that they cause a crash is very rare. Especially in commercial jets with multiple redundancies etc. It can be a contributing factor, of course.

Without any statistics, going just by my gut feeling reading incident reports as published on the aviation Herald i see tires bursting on various landings. But thats about it. There have been a few cases of problems with altimeters.

See http://avherald.com/h?list=&opt=0

Just note that the avherald doesn't reflect everything that is happening. So its more a random selection top of the ice berg, but still interesting to get a feeling for what happens every day

[Gansan]

Are the aircraft tyres filled with nitrogen, and up to what pressure?

[coolboy007]

Originally Posted by Gansan

Are the aircraft tyres filled with nitrogen, and up to what pressure?

Yes, they are filled with nitrogen as it is really required for aircraft tyres. I do not have the exact figures but for the A320, nose wheel tyre pressure is around 190 PSi and the main wheel pressure is around 210-215 Psi.

[searchingheaven]

An interesting article on the 777 in popular mechanics when it was first launched 22 years ago. Also shows the folding wingtip design. The design was to ensure that 777s fit in a a gate designed for the DC-10.

[searchingheaven]

The second half of the above article.

[Jeroen]

There are quite a few books about the 777.

I always like this series, from the flighdeck. It describes in detail a complete flight from Gatwick to Atlanta with a BA777. Lots of photographs, diagrams etc

http://www.amazon.com/Flightdeck-10-...oeing+777+book

I have several of these on several Boeings, 757, 747, (but not (yet) the 777.

There are also these sort of DVD's. More or less like the book, a flight from the beginning to the end.

https://www.itvv.com/Civil-Aviation-...xperience.html

I have studied similar DVDs endlessly on the 747-400 of familiarising myself with the aircraft operation before stepping into the full motion simulator

Jeroen

[honeybee]

So I searched on YouTube for the Birmingham airport and watched a clip with several planes trying to land in crosswinds.

A couple of questions: I see a couple of planes very close to landing, but still deciding to go around, one even had its main wheels on the tarmac before it lifts off again and goes around. What gives? I can understand a few feet above the ground it's all shaky, but once on terra firma or within inches of touching it, should one go around?

I read in one of the posts above that while landing in a crosswind situation the nose of the aircraft may be pointing somewhere else, but the undercarriage is aligned with the runway - How do you do that? The only analogy I have is of beat-up and chassis-damaged vehicles with their body/nose pointing a few degrees right or left compared to the wheels. How do you do that in a modern airplane?

Sorry, a third question - On touchdown, do you guys just kill the power/throttle, like go from 40% power to zero or something? Would that help in reducing the speed (and in turn the lift) and help keep the aircraft 'down' on the tarmac?

Part of the third question above, really - with flaps out during the landing approach, you get more lift at reduced speeds. Also at touchdown, there are 'brakes'? or some flaps which are raised 'above' the wings to brake the speed. At this point, would it help to retract the flaps back in to prevent generation of lift, which would lift the aircraft again in air? Or do you NOT do it just to allow you to go around even after a touchdown?

[Nempuguru]

Thank you so much searchingheaven, also Coolboy007, Jeroen for this wonderful thread and detailed information you have shared regarding Boeing 777 and other planes.

Little OT! If experts here could brief little on this topic. Mods please delete this post if it is irrelevant.

First MH370, now MS804! How could such a big jets with latest tracking system, sensor, gizmos disappear suddenly without much distress signals?

Is it really a worrying factor for aviation industry?

[Motard_Blr]

A few questions about cross wind landings:

During cross wind landings the aircraft is in nose up, approaching the runway at an angle (pitch up + yaw?). In such a situation:
1) Can the pilots actually see the runway and is it necessary to be able to see the runway?

2) How do you judge the distance of the main landing gear to the ground to know when to return the rudder to the centre?

3) With the main landing gear at an angle to the runway and the direction of motion and the fact they are not castors, aren't they subjected to huge forces when the tyres make contact with the ground? If so, would there a limitation on the number of cross wind landings before major parts need to be changed?

Thanks!

[searchingheaven]

Motard_blr and honeybee, please go through this first and then read my answers to your questions.

Methods of crosswind landings

There are two usual methods of accomplishing a crosswind approach and landing—the crab method and the side slip method.

Crab Method
The crab method is accomplished by establishing a heading (crab) in the direction of the wind with the wings level so that the aircraft’s track remains aligned with the centerline of the runway. This can be confusing but try to understand. The nose points in a different direction but the aircraft keeps itself aligned with the centerline. This crab angle is continued until just before touchdown, when the longitudinal axis of the aircraft must be aligned with the runway to avoid sideward contact of the wheels with the runway. The objective of this technique is to maintain wings level throughout the approach, flare, and touchdown.


The crab method has one other variation called crab touchdown. In this method, the aircraft can land on using crab only i.e. without the removal of crab angle. This is recommended on only slippery runways. Landing the airplane using crab only reduces drift toward the downwind side at touchdown and permits rapid operation of spoilers and autobrakes because all main gears touchdown simultaneously. This method puts excessive force and side load on the gear.

Side-Slip Method
This method ensures that the aircraft’s ground track and longitudinal axis are aligned with the runway centerline throughout the approach and landing. This method prevents excessive side loads on the landing gear. We align the aircraft’s heading with the centerline of the runway and then apply drift correction by lowering the upwind wing. This causes the plane to turn in that direction. Then we use the rudder for directional control. The drift is controlled with aileron, and the heading with rudder. The aircraft now side slips is such a way that both the heading and track are aligned with the centerline.

Side-Slip method

Originally Posted by Motard_Blr

1) Can the pilots actually see the runway and is it necessary to be able to see the runway?

2) How do you judge the distance of the main landing gear to the ground to know when to return the rudder to the centre?

3) With the main landing gear at an angle to the runway and the direction of motion and the fact they are not castors, aren't they subjected to huge forces when the tyres make contact with the ground? If so, would there a limitation on the number of cross wind landings before major parts need to be changed?

Thanks!

1. Having visual contact with the runway is a requirement. If we cannot see the runway at the DA(H) - Decision altitude or height, we have to go around.

2. As said earlier, rudder is not always returned to the center when the aircraft touches down. In fact, on the 777, the rudder is used for directional control till the speed goes down to 30 knots. Remember that the rudder also controls the nose-wheel steering upto some degree.

3. In the first paragraph of this post, I have stated that crab landings, the one in which crab is not removed even on touchdown are used only in slippery conditions. If there is a landing in which the aircraft touches down very hard or with excessive side loads on the gear, the gear is inspected thoroughly for any damage before the aircraft departs for the next leg.

Originally Posted by honeybee

A couple of questions: I see a couple of planes very close to landing, but still deciding to go around, one even had its main wheels on the tarmac before it lifts off again and goes around. What gives? I can understand a few feet above the ground it's all shaky, but once on terra firma or within inches of touching it, should one go around?

I read in one of the posts above that while landing in a crosswind situation the nose of the aircraft may be pointing somewhere else, but the undercarriage is aligned with the runway - How do you do that? The only analogy I have is of beat-up and chassis-damaged vehicles with their body/nose pointing a few degrees right or left compared to the wheels. How do you do that in a modern airplane?

Sorry, a third question - On touchdown, do you guys just kill the power/throttle, like go from 40% power to zero or something? Would that help in reducing the speed (and in turn the lift) and help keep the aircraft 'down' on the tarmac?

Part of the third question above, really - with flaps out during the landing approach, you get more lift at reduced speeds. Also at touchdown, there are 'brakes'? or some flaps which are raised 'above' the wings to brake the speed. At this point, would it help to retract the flaps back in to prevent generation of lift, which would lift the aircraft again in air? Or do you NOT do it just to allow you to go around even after a touchdown?

1. Yes, if you run out of rudder authority or don’t feel comfortable attempting the landing, you can and you should go around. During an automatic go-around initiated at 50 feet, approximately 30 feet of altitude is lost. If touchdown occurs after a go-around is initiated, the go-around continues.

2. Read the first paragraph about the crab landing.

3. The thrust levers are reduced to idle before touchdown. Then reverse thrust is applied upto a maximum speed of 60 knots, since it isn't effective below that speed. Then it is slowly reduced upto REV IDLE till we reach 30 knots taxi speed, at which point we shut the reverse thrust off.

4. Settling down the aircraft down on the runway is the job of the speedbrakes or the spoilers, what you're calling the "some flaps which are raised 'above' the wings". The speedbrakes spoil the lift from the wings, which places the airplane weight on the main landing gear, providing excellent brake effectiveness. Normally, these spoiler/speedbrakes are armed and as soon as a touchdown is sensed by the weight on wheel sensor, these are extended automatically. In case it does not extend automatically on touchdown, we have to do it manually.

Flaps are not retracted since they take a lot of time to retract and extend. By the time you retract them completely from full flaps to 0, you would've completed your landing roll. Also important is the go around requirement. It is much better to use the spoilers.

Originally Posted by Nempuguru

Little OT! If experts here could brief little on this topic. Mods please delete this post if it is irrelevant.

I will be answering these questions in the Egyptair 804 thread in Shifting Gears forum.

[Nempuguru]

Thank you. Some how I missed your MS804 thread.

http://www.team-bhp.com/forum/shifti...anean-sea.html

Originally Posted by searchingheaven

I will be answering these questions in the Egyptair 804 thread in Shifting Gears forum.