How much is autopilot on commercial flights today?

First of all, sorry, mxs, for the late reply but I've been working...

"Mxsmanic" schrieb im Newsbeitrag
...
Michael Nouak writes:

Oh yeah: I didn't gain any flying experience either from keeping the
needles
centered. And I didn't get to read my newspaper.

So you're saying that even flying the aircraft yourself is essentially
just a matter of watching the needles? Is this because you must stay
exactly right on the flight path? I take it there is very little
margin for pilot discretion on commercial flights.

Let me start again with the short answer, which is, surprise: yes

And now a bit more long-windedness:

To be sure, commercial a/c will fly happily on full manual, i. e. with A/P,
F/D and A/T off. There is no problem flying visual patterns until your tanks
are dry if you're so inclined. You could navigate by pilotage if you wanted
to. You could take off from St. Louis and say to yourself: "If'n I jess
follow that thar rivah down south, b'gosh at some point I must be in
Nawlins." OK, so my twang is pretty bad (hey, I'm just a furrinah :-)), but
I think you get the point.

Unfortunately, that's not what airlining is about. In a commercial
environment, it is your job, as a pilot, to fly SIDs, STARs, and Airways
with best possible precision. The reasons for that precision requirement are
quite numerous. As far as SIDs and STARs are concerned, more often than not
the main reason is noise abatement. Obstacle avoidance is, of course,
another good one! On Airways, the reasons may be to make ATCs job of
providing separation easier; to stay clear of prohibited airspace; etc.

Obviously, best possible precision is achieved by the A/P, which happens to
be linked to the Flight Management System (FMS), which calculates the
required track. However, when flying manually, whether by choice or
malfunction, the next best level of precision is provided by the F/D, which
is also linked to the FMS. And that's what I meant by "keeping the needles
centered." It's my job to fly the required track as accurately as possible,
and I do that best by following the F/D. If the F/D fails, the next best
level of precision is provided by the Navigation Display, which shows, among
other things, the required track, an airplane symbol, the heading I'm flying
and the track I'm flying. With both A/P and F/D inop, I would then try to
manipulate the controls such that the airplane symbol is over the track line
and the indicated track flown coincides with the required track.

I think you can see that a lot of equipment needs to fail to lower the best
possible precision to the level of pilotage.

With all that said, it is possible to deviate from the required track if
necessary. Best example, especially at this time of the year, would be if
you saw a TS (either visually or on weather radar) lying across your track.

A short note about A/Ls:

Long years ago I came into CDG on a flight from LAX and noticed that
the landing was glassy smooth despite essentially zero visibility (in
fact, I didn't know we were on the ground until I saw buildings in the
distance rushing by outside the window). At the time I thought it was
just a very good pilot. Now I suppose that it was actually an
autolanding--the best pilot of all.

During an A/L, the A/P will put the a/c down in the Touch-Down Zone, come
what may. I've seen A/Ls that were smooth as glass, and others that ended
with a pretty solid thump. I'm glad to report that the smoothest landings
I've seen were performed by either myself or my human colleagues!

Crews will usually elect to perform an A/L well before the weather is such
that it is an absolute requirement. With a reported ceiling of 250' and fog
patches, it makes little sense to hand-fly the approach, only to see that at
200', big surprise!, you're in a fog patch and have to go around. It would
also be rather difficult to explain to management.

HTH!

--
Michael Nouak
remove "nospamfor" to reply:

Michael Nouak writes:

As far as SIDs and STARs are concerned, more often than not
the main reason is noise abatement.

I'm surprised that noise abatement is still an issue. Modern
high-bypass turbofans are very quiet compared to their turbojet
ancestors of a few decades ago.

I used to live directly beneath the approach path of a very large
airport and had aircraft flying over my house every few minutes on
most days, but I never even noticed any noise. However, some people
down the street in a retirement community constantly complained about
the noise. I'm not sure how they managed to hear it when I didn't.

--
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Mxsmanic wrote:
Michael Nouak writes:

As far as SIDs and STARs are concerned, more often than not
the main reason is noise abatement.

I'm surprised that noise abatement is still an issue. Modern
high-bypass turbofans are very quiet compared to their turbojet
ancestors of a few decades ago.

I work for a manufacturer of high-bypass turbofans and they're still
extremely loud. I also live next to one of the busiest airports in the
country. Believe me, there's not much difference between old and new.

Emily writes:

I work for a manufacturer of high-bypass turbofans and they're still
extremely loud.

Turbojets are ear-splitting even from the observation decks from which
I used to watch them. Turbofans are hard to hear more than a few
hundred metres away. They may sound very loud, but that's only
because it's hard to remember how low turbojets were. Military
aircraft can serve as a good reminder of how loud engines can get (for
an extreme example, the SR-71 is a good test, with its turbojets that
cruise in afterburner).

Believe me, there's not much difference between old and new.

How can you be so sure? There isn't much of the old around any more.

--
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("Emily" wrote)
I work for a manufacturer of high-bypass turbofans and they're still
extremely loud. I also live next to one of the busiest airports in the
country. Believe me, there's not much difference between old and new.


Not sure if Honda's "GE-Honda" HF118 Turbofan Engine qualifies as
'high-bipass'
....it is extremely quiet.

On flybys at OSH, the HondaJet sounded like a handheld hairdryer, left
running across the room - on medium.

"The HF118 produces 1,700 lbf of thrust, and meets ICAO Stage IV noise
requirements. The sole application as of 2006 is for the HA-420 HondaJet."

http://en.wikipedia.org/wiki/Turbofan
Learning about high-bypass turbofans.... g


Montblack

Montblack writes:

Not sure if Honda's "GE-Honda" HF118 Turbofan Engine qualifies as
'high-bipass'
...it is extremely quiet.

You can usually recognize high-bypass fans because they are quite fat
in front (because of the large fan), and often the nacelle has two
salient parts, a fat part in the front and a thinner part in the back.

They are quieter because the flow of air from the fan acts as a buffer
between the noisy flow from the exhaust and the surrounding air. They
are also more efficient than turbojets at high subsonic speeds. I
think there is at least one supersonic turbofan design, but I don't
know to what extent they are used for this in production aircraft.

--
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"Montblack" wrote

On flybys at OSH, the HondaJet sounded like a handheld hairdryer, left
running across the room - on medium.

"The HF118 produces 1,700 lbf of thrust, and meets ICAO Stage IV noise
requirements. The sole application as of 2006 is for the HA-420 HondaJet."

It is also very important as to how the engine is installed, and the
attention given to intake and exhaust profiles.

The C-17, for example, is about the quietest transport I have ever heard.
When you look at the intake, there is something unusual to it. All over on
the inside of the intake, there a hundreds if not thousands of small (1/8th
inch ?) holes, drilled in specific patterns. They are said to have a large
effect on absorbing the shrill noise coming from the compressor, and leaving
out the front of the engine. I would bet that there are some tricks to the
Honda ducting and installation, also.

It also occurs to me that the engine being above the wing would block some
of the noise from reaching the ground. Anyone know about that?
--
Jim in NC