Ask The Pilot

[jb747]

So, we've pretty much established that it probably wasn't the nose gear that caused the issue.

Thrust asymmetry at low power settings is a real gotcha. Even the biggest aircraft will do a wonderfully quick turn, if one engine fails during the period of acceleration from about 80% up. There isn't enough rudder or nose gear authority to stop the swing. But, slamming all of the levers to idle stops everything, and the aircraft is (in the sim at least) normally stoppable within the confines of the runway.

In this event, they are well off the runway. Well beyond what I'd expect. Additionally, only one engine appears to be in reverse. There might be a bit more to this one.

 

[jb747]

The second was highly problematical although it looked real enough. Same initial problem, a jammed nose wheel but an entirely different solution - a Nissan pick up positioned itself in front of the landing aircraft, matched its speed and allowed the pilot to drop the nose wheel into the back of the truck. Is this for real?

It's an advertisement. Firstly there is no way on this earth that having a vehicle in that position is even a little bit acceptable. But, much more important, is the fact that no factory Nissan truck on this planet is that fast.

Question - how often is a nose wheel problem encountered whereby the wheel in unable to be steered even though it has lowered and locked properly? Is this something you prepare for in the SIM?

We have three ways of turning the aircraft on the ground. The tiller, which gives up to 70º of nose gear steering, but is only used a low speeds. The rudder pedal interconnect, which gives up to 7º of nose gear steering via the rudder pedals. The rudder itself, which starts to overpower the nose gear steering from about 60 knots. And differential braking. All of the methods overlap, and may be used at any time. So, the problematic nose gear you've proposed, would stop us from taxiing , but shouldn't present too much of a problem with regards to stopping on the runway. You just as likely wouldn't even notice.

Turned through a large amount and stuck (i.e. the A320 in the USA), the tyre would not be rotating, and would give virtually zero sideways force. So again (as as shown on the video) not an issue.

A wheel that was stuck at 10-20º would be much more of an issue, as the tyre would be turning, and would produce a substantial side loading. You'd most certainly know, but should have the ability to overpower it, especially with braking.

 

[Quickstatus]

There was a QF747 which accelerated down runway for takeoff with nosewheel stuck at 90 deg

Actually A380:
https://www.youtube.com/watch?v=dIxML27c_q8

 

[jb747]

Actually A380:
https://www.youtube.com/watch?v=dIxML27c_q8

Somewhere or other on the net, there's a picture of a 747 (an SP if I recall correctly) landing with the nose gear coughed off.

The video referenced above is a classic example of assymetric thrust increase pushing the nose, irrespective of the nose the steering position. In that instance, the right engine(s) have accelerated before the left, and bingo, left turn. The 747 wasn't particularly prone to the issue, as the EECs would control the thrust increase to match the slowest accelerating engine. The 380 doesn't behave this way, and will give you a nasty wake up call if you revert to flying Boeing.

 

[Quickstatus]

I have often experience engine spool up for takeoff just as the aircraft enters the runway while still taxiing. Is this just an incorrect perception and does engine power only increase for takeoff when everything is lined up?

 

[jb747]

I have often experience engine spool up for takeoff just as the aircraft enters the runway while still taxiing. Is this just an incorrect perception and does engine power only increase for takeoff when everything is lined up?

Domestic aircraft, which are both smaller, and more likely to be placed on a runway with an 'immediate' requirement, are where you'll often see the thrust being increased during the turn. It's mostly a relatively small amount though (towards the initial setting at which you wait for them to stabilise), and never to the take off position (until approximately aligned). Too much power, too soon, and you'll demonstrate that aircraft are horrid understeerers .... great aircraft, but lousy cars.

Oh, and the stable settings are in the area of 25-40%, not 60% as mentioned earlier.

Large aircraft may use asymmetric power to help them turn. An extra 10% on an outboard engine makes a lot of difference. But, it also makes asymmetric acceleration much more likely, so you need to be wary of it if used to line up.

 

[clazman]

Looking at flight radar I have noticed, CX take different routes when they fly JFK - HK.

It appears that sometimes they fly right and head out over Greenland, but the majority of the time fly out left through Ontario.

Is this just a illusion of a flat map?

Are you aware of any routes where pilots can take completely different routes for the same flight

 

[jb747]

Looking at flight radar I have noticed, CX take different routes when they fly JFK - HK.

It appears that sometimes they fly right and head out over Greenland, but the majority of the time fly out left through Ontario.

Is this just a illusion of a flat map?

Are you aware of any routes where pilots can take completely different routes for the same flight

Many routes are constrained by politics, and so are flown pretty well the same way every day. When we flew over Afghanistan, there were only about 5 available routings, and depending upon the colour of the moon, you could be on any of them.

Oceanic routes are generally much less constrained, and can vary dramatically on consecutive days. The main factor here will be the wind, and the desire of the flight planners to find the route with the minimum fuel burn. The routes we take between Melbourne and LA could be up to 2,000 miles apart.

Other than the weather, route choice could be affected by overflight costs or congestion. The final route chosen will try to address all of the competing factors.

 

[bryanjones]

What qualifications would a typical flight planner have? Seems quite a technical discipline.

 

[clazman]

What country's are no fly zones, would assume Syria and North Korea.....

 

[Flying Fox]

Currently there is a QF A380 stuck in DXB. Does QF have their own engineers & parts there or does EK do all the work for QF and then QF gets a bill?

Any idea why the QF bird has been grounded for so long?

 

[por930]

Currently there is a QF A380 stuck in DXB. Does QF have their own engineers & parts there or does EK do all the work for QF and then QF gets a bill?

Any idea why the QF bird has been grounded for so long?

From the PPRuNe forum, an engineer by the looks,"Wiring issues with the fuel sys from what I hear."

 

[Quickstatus]

What country's are no fly zones, would assume Syria and North Korea.....

Add Ukraine? . Israel for some?

 

[jb747]

What qualifications would a typical flight planner have? Seems quite a technical discipline.

From what I've heard (and this may not be correct) they have to do the CASA flight planning and navigation exams. Beyond that, I think they are trained and recruited internally. Our previous head of the department was an incredibly knowledgable and able planner, and all those who he trained are very good.

 

[jb747]

Currently there is a QF A380 stuck in DXB. Does QF have their own engineers & parts there or does EK do all the work for QF and then QF gets a bill?

All airlines use a mix of their own, contractors, and local airlines for work. All depends upon the need. Aircraft carry a supply of most used spares on board. More complex, but still commonly used, may be stockpiled at a few locations. Rarely used items will most likely need to come from the manufacturers. Nobody keeps spares of everything.

There is a loan (pool) system for some items, though I doubt that the 380 would be included (not common enough). I recall borrowing an EK AD/IRU a while back. It was on the condition that it came back on the next flight.

Any idea why the QF bird has been grounded for so long?

'cos it isn't fixed.

I don't know.

 

[bryanjones]

.... Aircraft carry a supply of most used spares on board. More complex, but still commonly used, may be stockpiled at a few locations. ...

Interesting...Wouldn't it make sense for the 380 just to have the most used spares at LHR, DXB, MEL, etc - or is the weight of these spares so small that it is just better to have it easily accessible within a few minutes for a quick turnaround?

 

[clazman]

Interesting...Wouldn't it make sense for the 380 just to have the most used spares at LHR, DXB, MEL, etc - or is the weight of these spares so small that it is just better to have it easily accessible within a few minutes for a quick turnaround?

On the Dubai airport show one of the engineers said that they carry certain spares on board, cant recall if it was A 777 or 380

 

[andmiz]

From what I've heard (and this may not be correct) they have to do the CASA flight planning and navigation exams. Beyond that, I think they are trained and recruited internally. Our previous head of the department was an incredibly knowledgable and able planner, and all those who he trained are very good.

You can't sit the relevant CASA exams without a commercial pilot licence. Like QF, ours are just internally trained...what seems like a 2 week course to let the computer do the work. Thinking 'outside the box' is left to the pilots in dispatch and the more cluey supervisors.

 

[Quickstatus]

On the Dubai airport show one of the engineers said that they carry certain spares on board, cant recall if it was A 777 or 380

Are the spares so expensive that it is cheaper for them to be carried on board (with a fuel and weight penalty) than stored on the grounds at certain airports?

 

[Quickstatus]

An aerodynamic question:

What is the practical difference between a stiff wing and a wing with less rigidity.

Seems like the B787 has a 'flexible" wing.