Problems in a commercial flight

Correction: Actually, Mxsmanic knows a great deal, _despite_ not being a
pilot.

I cannot disagree with this.

The problem is that you do not know what you do not know, and lack of
practical experience has left your knowledge with a great number of
holes that you refuse to acknowledge.

It is a typically sophomoric attitude (hence my initial impression
that you were an adolescent).

This is particularly true with respect to large aircraft, since most
of the pilots here are familiar only with the tiny aircraft they fly, whereas
he has studied both small and large aircraft.

That is a GROSS generalization.

Yes, some pilot's only care about the planes that they fly... I would
say that is actually the exception rather than the rule, however.

The rest of us have just as much a passion for aviation as yourself
AND we fly. When we're not spending our spare time in a cockpit, we
spend it learning about aircraft and aircraft systems... Aircraft
design (A particular favorite topic of mine) and other aviation
related topics... and hell, even flying sims...

More to the point: If you see an error in anything I've said, feel free to
point it out.

Your explanation of the cause of the roll oscillations was utterly
wrong, and your desire to attribute ultimate aircraft stability to
autopilot design is also largly incorrect (Except in a few isolated
(almost always military) cases of relaxed stability aircraft.

He doesn't have to pretend.

This might be a low blow but...

Isn't that the fundamental definition of Simulation?

Nor is he so insecure that he must engage in personal attacks if someone else seems to know more.

I actually agree that the personal attacks against you have grown more
disruptive than your actual sophomoric nature.

One of the aggravations I have had, however - is you do not seem to
respond to anything BUT the personal attacks - I have seen MANY
knowledgeable, polite corrections and responses to your assertions go
un-heeded while you chose only to argue with those who attacked you.
It gives the impression that you seek the negative attention over
actual helpfulness.

I still wish you'd take some time to get your information from sources
OTHER than public forums however... So many of your questions could be
answered so much easier and faster via a quick Google search.

And It would also be nice if you added an occasional "my understanding
is" disclaimer to some of your more authoritative-toned posts...

Mxsmanic wrote in
:

C J Campbell writes:

Just so you know, Msxmanic does not know any more about flight than
you do. He is not a pilot.

Correction: Actually, Mxsmanic knows a great deal,

No, you don't




bertie

Soooo..

How come he (MX) was able to give a rather complete and correct
answer to the poster's question?

Care to give it a try?

Dave



On Tue, 13 Mar 2007 22:44:15 -0700, C J Campbell
wrote:

On 2007-03-13 17:43:50 -0700, megaMAX
said:

On Wed, 14 Mar 2007 01:18:33 +0100, Mxsmanic
wrote:

Most commercial flights are flown on autopilot for the vast majority of the
trip. Thus you would have seen autopilot corrections, not pilot corrections.

Just so you know, Msxmanic does not know any more about flight than you
do. He is not a pilot. He is just some nut who hangs out here and
pretends to know what he is talking about.

I was flying in an Air Jamaica jet many years ago and while cruising
noticed large reddish flames from the exhaust of the Rolls Royce engine.
How "normal" would that be?

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

On Mar 15, 11:59 am, Dave wrote:
Soooo..

How come he (MX) was able to give a rather complete and correct
answer to the poster's question?

Care to give it a try?

More than possible that the poster had a middle ear infection.
Not having instruments and the training to use them while back among
the self loading cargo how could any-one tell what the aircraft was
doing?

On Mar 14, 3:59 pm, Dave wrote:
Soooo..

How come he (MX) was able to give a rather complete and correct
answer to the poster's question?

Care to give it a try?

Dave

On Tue, 13 Mar 2007 22:44:15 -0700, C J Campbell

wrote:
On 2007-03-13 17:43:50 -0700, megaMAX
said:

On Wed, 14 Mar 2007 01:18:33 +0100, Mxsmanic
wrote:

Most commercial flights are flown on autopilot for the vast majority of the
trip. Thus you would have seen autopilot corrections, not pilot corrections.

Just so you know, Msxmanic does not know any more about flight than you
do. He is not a pilot. He is just some nut who hangs out here and
pretends to know what he is talking about.

MX's knowledge is very sophomoric, and heavily stilted towards biases
introduced by inaccuracies in his simulations.

As in this case.

Minor Harmonic oscillations in flights are a natural byproduct of the
dynamic stability of modern aircraft. The Autopilot has no part in
it.

When the oscillations are on the Longitudinal axis, they are called
phugoid oscillations, I'm not sure if there is a similar term for the
roll equivolents, but it is the same deal- Essentially what is
happening is a battle between the aircraft's substantial momentum, and
the aerodynamic forces which keep it pointed into the wind... Large
out-of-trim deflections (both roll and pitch) are damped quickly, but
there is a threshold at which the amplitude of the oscillations falls
below the aerodynamics ability to produce large enough forces to damp
the behavior...

The period and amplitude of these harmonic functions are directly
related to the configuration and chord of the aerodynamic surfaces vs.
The aircraft's distribution of mass. In general, thinner aerodynamic
surfaces create stronger off-center aerodynamic forces and hence
better damping, and lighter aircraft produce weaker momentum forces
and again, fewer oscillations. Granted, 'fewer' in this case is a
matter of perception... the oscillations you were seeing were really
very minor (less than a degree), its just that the solid horizon
combined with the long arm of the wing made them more obvious than the
same fraction of a degree roll oscillation would be in a smaller
aircraft.

No MX... it has nothing to do with the autopilot...

FWIW, I remember reading somewhere that the 747 prototype actually had
a problem on its first few flights - the engineers had designed the
aerodynamic surfaces to damp the phugoid (longitudinal) harmonics
based on a theoretical perfectly rigid aircraft, however, in reality,
it turned out that the fuselage had a natural bending resonance
frequency which matched the aerodynamic harmonic frequency, and they
amplified eachother to produce an in flight longitudinal harmonic that
was actually quite substantial... the result, IIRC, was a very sick
planeload of journalists on the aircraft's first publicity flight.

For more information, read up on both Phugoid oscillations and Roll
stability via using wing dihedral.

On 2007-03-14 15:59:45 -0700, Dave said:

Soooo..

How come he (MX) was able to give a rather complete and correct
answer to the poster's question?

Care to give it a try?

Dave

The fact that he is right once in awhile is no indication that he knows
what he is talking about. He is not a pilot. He is a flight-sim guy.
Even Mxs should be able to learn something. But what he says should in
no way be considered reliable.

--
Waddling Eagle
World Famous Flight Instructor

megaMAX wrote in
:

On Wed, 14 Mar 2007 01:18:33 +0100, Mxsmanic
wrote:

Most commercial flights are flown on autopilot for the vast majority
of the trip. Thus you would have seen autopilot corrections, not
pilot corrections.

Yes, this is really probable, since it was a very regular and periodic
correction, every few seconds.

Most likely there was nothing wrong, so there was nothing that needed
to be done. Constant small corrections are normal in flight. If
there are substantial winds aloft (and there usually are), the
corrections are likely to be mostly in one direction.

Ok, but what about landing? The landing runway wasn't in the same
direction of the rest of the flight, so the wind probably was blowing
in a different direction.

My sensation was that, at the moment of landing, the pilot was really
not able to have a good trim due to a decise clockwise roll, that he
was really not able to correct with the normal actions, despite of
various tentatives. The impression was like that the right engine was
not enough "powerful", or the airplane was heavier on the right side.
Of course, impressions of a not-expert people.

But since I had a large number of flights in my life and I know what
happens in case of lateral wind, also during landing, I repeat that my
sensation was not of lateral wind.

From your description, there is no reason to believe that the flight
was in any danger, and the corrections sound like nothing more than
what is normal for any flight.

Ok, thank you: I was really calm during the flight, only after landing
I was wondering about what has happened and I was curious about that.


you're an idiot


Bertie

megaMAX wrote:
Hello everybody,
I want to tell you what's happened during a Finnair flight from
Helsinki to Milan, I'm not an expert of flight.

During the entire flight, I noticed that the aircraft was continuosly
rolling to right, and the pilot was correcting every 10-20 seconds the
attitude. I noticed this, because I was looking to the right wing and
the wing was continuosly going down of few centimeters, and after few
seconds there was a slight correction.

During landing, the aircraft was definitively rolling clockwise, in
fact when we touched the ground, it was really yawing and sliding, and
the pilot had to take a decise correction in order to align the
aircraft to the track.

I'm really not an expert, but I was wondering:

- what could have been the problem? The right engine?
- the pilot behaved correctly, completing the flight until destination
and trying this landing? An intermediate step could have been better?
- we have been in some danger, during the flight or at the moment of
landing?
- this episodes are made pubblic in some register, or the companies
try to hide them as much as possible?

Thanks!
Max

That is normal. Most airplanes will "wander" just a little when on
autopilot.

Matt

On 2007-03-13 16:08:34 -0700, megaMAX
said:

Hello everybody,
I want to tell you what's happened during a Finnair flight from
Helsinki to Milan, I'm not an expert of flight.

During the entire flight, I noticed that the aircraft was continuosly
rolling to right, and the pilot was correcting every 10-20 seconds the
attitude. I noticed this, because I was looking to the right wing and
the wing was continuosly going down of few centimeters, and after few
seconds there was a slight correction.

Not unusual at all. It could just be normal cycling of the autopilot.


During landing, the aircraft was definitively rolling clockwise, in
fact when we touched the ground, it was really yawing and sliding, and
the pilot had to take a decise correction in order to align the
aircraft to the track.

This is also normal in a crosswind landing. The wind is blowing from
the direction that the wing is down. Since the pilot does not want to
land too much sideways, he will kick the plane around so it points
straight down the runway just before touchdown.


I'm really not an expert, but I was wondering:

- what could have been the problem? The right engine?
- the pilot behaved correctly, completing the flight until destination
and trying this landing? An intermediate step could have been better?
- we have been in some danger, during the flight or at the moment of
landing?
- this episodes are made pubblic in some register, or the companies
try to hide them as much as possible?

Minor problems with the airplane are recorded in the airplane's
logbooks. In the US, accidents are recorded in the NTSB database. Not
all countries maintain such a database, however.


Thanks!
Max


--
Waddling Eagle
World Famous Flight Instructor