Ask The Pilot

[por930]

JB, Now we are starting to see the likes of the 787 doing long distance trips, eg, Melbourne-Lax, I have often thought the heavier aircraft such as the 747 and A380) handled turbulence better(less abrupt movements) in similar conditions. I recall traveling to Japan on QF21(747) and a 2 days later back via Jetstar on the A330. Both trips had a fair bit of turbulence close to Japan. The 747 seemed to plough through pretty well, whereas the lighter A330 seemed to bounce and jolt a lot more. I realise the conditions could have been quite different.

How do you think the A380 would compare with the 787 at the same altitude, same conditions on the Melbourne-Lax trip? As another extreme, you in your A380, and me in my Cessna 182 at 10,000 would have quite a different ride in similar conditions?

 

[jb747]

Re: Ask the pilot

Does the max landing weight differ by airport/runway length? Or is it the max weight that the aircraft can safely handle? Or are there limits for both?

Basically there are always two limits.

The maximum structural landing weight, is the weight at which the aircraft can be landed with a given rate of descent at touchdown without any damage. In an emergency aircraft can be landed at heavier weights, but you will break something if the touchdown isn't smooth....which is why auto land is preferred in any overweight landing.

The second limit is the performance limit. This varies with runway length and conditions. It can also be affected by any go around gradient requirements.

A third, but less common limit, can exist where runways or taxiways, have designated weight limits.

 

[jb747]

JB, Now we are starting to see the likes of the 787 doing long distance trips, eg, Melbourne-Lax, I have often thought the heavier aircraft such as the 747 and A380) handled turbulence better(less abrupt movements) in similar conditions. I recall traveling to Japan on QF21(747) and a 2 days later back via Jetstar on the A330. Both trips had a fair bit of turbulence close to Japan. The 747 seemed to plough through pretty well, whereas the lighter A330 seemed to bounce and jolt a lot more. I realise the conditions could have been quite different.

The wing loading of an aircraft is the weight that a given area of the wing has to carry. As a starter, the higher the wing loading, the less an aircraft is affected by turbulence. So, a fighter, with a tiny wing, and high loading, could well have an inherently better ride than an airliner. Beyond that though, some structures a more rigid than others, and the less rigid the structure is, the more it tends to act as a shock absorber. Flight controls that actively try to protect the structure (i.e. most of the FBW airliners) may tend to make the motions worse...they care about the metal bits, not the passengers. So there are always competing factors that will affect the ride.

How do you think the A380 would compare with the 787 at the same altitude, same conditions on the Melbourne-Lax trip? As another extreme, you in your A380, and me in my Cessna 182 at 10,000 would have quite a different ride in similar conditions?

I'd expect the 380 to have the better ride, as it's a much bigger and more flexible structure...but I've never set foot in a 787, so I could well be wrong.

 

[Quickstatus]

Now that the SFO Asiana crash NTSB report has been released and probable cause partly/mostly due to flight crew mismanagement, what will become of the careers of the flight crew.

Humans will always make mistakes, so should pilots really be one bad mistake from the end of one's career

 

[jb747]

Now that the SFO Asiana crash NTSB report has been released and probable cause partly/mostly due to flight crew mismanagement, what will become of the careers of the flight crew.

Humans will always make mistakes, so should pilots really be one bad mistake from the end of one's career

It's very dependent upon the culture of both the airline and the country. It's pretty standard for airlines to get rid of the crew who made the error, as for many, that will be seen as fixing the problem. Most won't admit that there are often endemic issues. And I've never heard of any airline admitting to management problems.

 

[flychrisfly]

Each runway will have a max landing weight which depends on current ambient conditions (temp, barometric pressure), wind, slope, aircraft serviceability (changes if things like anti skid are not working), anti icing on or off, and can be limited a number of ways by, for example, missed approach climb gradient or runway length.

How does slope affect landings overall? Obviously if landing 'down hill' it'll take longer to stop with all other things bneing equal, and I assume will lower the max landing weight, but what happens if the runway (like Shannon, from memory) is more of an S on it's side. Landed there once on the downhill slope before bottoming out in a "valley" and heading up the "hill" on the other side before cresting that hill to head down its far side. What would the slope be in this case? And what would the slope be if landing on the reciprocal runway?

 

[jb747]

How does slope affect landings overall? Obviously if landing 'down hill' it'll take longer to stop with all other things bneing equal, and I assume will lower the max landing weight, but what happens if the runway (like Shannon, from memory) is more of an S on it's side. Landed there once on the downhill slope before bottoming out in a "valley" and heading up the "hill" on the other side before cresting that hill to head down its far side. What would the slope be in this case? And what would the slope be if landing on the reciprocal runway?

Plenty of runways like that. Melbourne 34 is pretty easy to consider, as it's basically uphill to the north (and by about 100', so quite a considerable amount). Darwin has a good hump on it, as does Manchester.

Basically though, the ups and downs aren't really of interest, the performance is based upon the overall rise or fall, over its full length.

Taking off, you accelerate faster downhill, and landing it's harder to stop. So, it's good to take off down hill, and land the other way, but the wind is normally the deciding factor.

Landing downhill, people tend to float...and uphill, well the runway just comes up and meets you.

 

[flychrisfly]

Plenty of runways like that. Melbourne 34 is pretty easy to consider, as it's basically uphill to the north (and by about 100', so quite a considerable amount).

100 feet? According to my (probably badly remembered) high school trigonometry that leads to an average slope of about 4.9 degrees over the 3657 metre runway?! That sounds like a lot!

 

[Boris spatsky]

100 feet? According to my (probably badly remembered) high school trigonometry that leads to an average slope of about 4.9 degrees over the 3657 metre runway?! That sounds like a lot!

You were close but no cigar It's a 0.9% gradient (or 0.49 degrees) so JB is right. The rise is close to 100 feet.

 

[mjt57]

You were close but no cigar It's a 0.9% gradient (or 0.49 degrees) so JB is right. The rise is close to 100 feet.

When you look out over the runways from the observation areas at MEL it looks pretty flat. But then so does my block, but it's a 60mm drop between the road gutter and the back of the house and that's only 20 metres. So it can be rather deceiving, I s'pose.

 

[harvyk]

Hopefully this isn't venturing too far into the security realm, so I understand if you don't want to answer there JB / Boris...

Just reading the following -> Selfies From the Flight Deck Land Pilot in Hot Water | Story and it got me thinking, what are the rules for photos in the flight deck?

My AFF avatar photo was taken from the flight deck, but that was 4 years ago (plus the pilot was cropped out prior to the photo going anywhere public), and as far as I knew flight deck visits where still allowed. Is this just a case of an over zealous airline / regulatory system, or have the rules changed for coughpit photos full stop?

 

[jb747]

Hopefully this isn't venturing too far into the security realm, so I understand if you don't want to answer there JB / Boris...

Just reading the following -> Selfies From the Flight Deck Land Pilot in Hot Water | Story and it got me thinking, what are the rules for photos in the flight deck?

My AFF avatar photo was taken from the flight deck, but that was 4 years ago (plus the pilot was cropped out prior to the photo going anywhere public), and as far as I knew flight deck visits where still allowed. Is this just a case of an over zealous airline / regulatory system, or have the rules changed for coughpit photos full stop?

As you're sitting in an operating seat, I assume the aircraft was on the ground. Such visits are still fine...as are the pictures. How else would I get my picture taken with Miranda Kerr?

I can't see any security issues (other than invented ones). All that anyone could possibly want to know about the coughpits is readily available from the manufacturers.

 

[Quickstatus]

As you're sitting in an operating seat, I assume the aircraft was on the ground. Such visits are still fine...as are the pictures. How else would I get my picture taken with Miranda Kerr?
.

Ah well that means I'll never get a look in with that competition

 

[harvyk]

As you're sitting in an operating seat, I assume the aircraft was on the ground. Such visits are still fine...as are the pictures. How else would I get my picture taken with Miranda Kerr?

I can't see any security issues (other than invented ones). All that anyone could possibly want to know about the coughpits is readily available from the manufacturers.

Thanks JB, pretty much what I was expecting.

Yes, in the photo the aircraft was on the ground, I was probably up there for a good 10 to 15 minutes talking with the pilots. The most memorable part was when the pilot turned around and said they needed to finish up, I thought it was my cue to leave, instead the pilot then asked me to turning some of the dials and put the shades up. As a plane geek it pretty much made my day (despite none of the switches I touched having any real consequences).

 

[mjt57]

JB, a question about turbine bearing vibrations.

Do you monitor them? Can the vibes be trended and are there any forced shutdowns (not pilot initiated) for vibes which go too high?

 

[jb747]

JB, a question about turbine bearing vibrations.

Do you monitor them? Can the vibes be trended and are there any forced shutdowns (not pilot initiated) for vibes which go too high?

All three spools are monitored and displayed on the secondary engine displays. They can force a shutdown, though it will be pilot initiated.

 

[PointyEnd]

G'day all.
I know that most airlines don't like pregnant women from flying near 'birthing' time but I was wondering how place of birth and citizenship are determined? Also, is it something that is covered in training? From what I can glean, carriers have different methods of classifying the above details. Have any of our pilots experienced/ heard of a mid-air birth?
Apologies if it has been covered before.
Cheers!

 

[jb747]

I know that most airlines don't like pregnant women from flying near 'birthing' time but I was wondering how place of birth and citizenship are determined? Also, is it something that is covered in training? From what I can glean, carriers have different methods of classifying the above details. Have any of our pilots experienced/ heard of a mid-air birth?

Well, they certainly happen, but thankfully I've never had any involvement in one.

Flying late in pregnancy is bad on a number of levels. From my perspective, it can force an unnecessary diversion...and perhaps to a place where you don't want your child born. It exposes the mother and the child to a birth in conditions in which needed medical attention may not be available, so from that point of view, I see it as irresponsible.

Citizenship won't be conferred by birth on an aircraft...that is decided by the laws of the country, not by a carrier. You'd have ask a lawyer that one.

 

[MEL_Traveller]

Citizenship won't be conferred by birth on an aircraft...that is decided by the laws of the country, not by a carrier. You'd have ask a lawyer that one.

In almost all cases citizenship will be conferred through the parents, and determined by the respective citizenship laws of the country(ies) in which the parents hold citizenship or otherwise reside.

Citizenship could theoretically be conferred in some circumstances by birth on an aircraft, if the person was otherwise stateless. But I can't think of any examples that would make that situation anything but extraordinarily rare.

 

[Quickstatus]

VH-OJS late out of JFK will arrive at 1110 into SYD.

apparently a starter motor had to be replaced. Part came from BA plane according to a friend on the flight.

What are these starter motors for? And are parts swopping a common practice?