Melbourne FL airport -- approach

I don't have an aviation background but was just curious. It seemed
that during the approach into Melbourne, FL we were relatively quite
low to the ground/water (as compared to other airports). Do planes
fly low into Melbourne?

Airline or large or turbojet aircraft that are required to
fly at an altitude that is 1500 feet above the runway,
unless a lower altitude is required. Furthermore, if the
runway has an ILS or VASI system, the pilot is required to
use the glide slope.

If you were in a general aviation, non-turbojet aircraft
smaller than 12,500 pounds, the pilot is required only to
fly at a safe altitude. Over water obstacle clearance is
not a big problem and simply avoiding boats by 500 feet is
all that is required.


--
James H. Macklin
ATP,CFI,A&P

"Tim923" wrote in message
...
|I don't have an aviation background but was just curious.
It seemed
| that during the approach into Melbourne, FL we were
relatively quite
| low to the ground/water (as compared to other airports).
Do planes
| fly low into Melbourne?

"Tim923" wrote in message
...
I don't have an aviation background but was just curious. It seemed
that during the approach into Melbourne, FL we were relatively quite
low to the ground/water (as compared to other airports). Do planes
fly low into Melbourne?

How did you measure you height above the water? How did you measure your
distance from the runway threshold?

Assuming you used reliable means to make those two measurements, you can
easily calculate the flight path angle remaining to the runway and compare
it to the usual glideslope used (typically 3 degrees, but it does vary a
little from one airport to another).

Until you have a documented discrepancy, it seems to me it's a bit premature
to ask whether planes typically fly low into Melbourne.

For what it's worth, the ILS glideslope at Melbourne is 2.8 degrees. At a
distance of 1 nautical mile from the runway threshold, this translates into
a height above the ground that is 21 feet lower than what one would find
using the standard 3 degree glideslope. A passenger inside an airliner
would not be able to notice this small a difference.

Of course, the ILS glideslope is relevant only when it's actually being used
for landing guidance, which is not true in every landing situation anyway.

The airplane in which you were riding may or may not have been lower than
normal. But "normal" at KMLB isn't significantly different from "normal" at
any other commercial airport.

Pete

It was a Delta commerical flight. Looking out the window, it appeared
that we were so close to the ocean we were going to hit it before we
circled around to land on the runway.

So, I was curious whether it was just error in perception, or if we
really were close to the ground/water. Melbourne is near the ocean,
and there are hardly any tall buildings in the area. The approach was
a loop or circle over the ocean and bay to the runway.

Just curious.

"Tim923" wrote in message
...
[...]
So, I was curious whether it was just error in perception, or if we
really were close to the ground/water. Melbourne is near the ocean,
and there are hardly any tall buildings in the area. The approach was
a loop or circle over the ocean and bay to the runway.

Especially if you were not on final approach, then I assure you any
perception that you "were so close to the ocean [you] were going to hit it"
was incorrect. As Jim points out, minimum altitudes prior to commencement
of the final approach are on the order of a thousand feet above the ground
or more. For example, at KMLB depending on the particular approach being
used, minimum altitudes are 1600, 1700, or 2000 feet for landings to the
west (runways 27L and 27R).

I suspect that a combination of very clear weather and particular water
conditions (higher, wide-spaced waves) may have led you to believe you were
much closer to the ground than you actually were.

I cannot rule out 100% that the airplane in which you were riding nearly
crashed, but that's only because I wasn't there and have no access to any
specific records regarding the flight. Even without that information, the
likelihood that the situation was as you perceived it to be is exceedingly
small (to the point of irrelevance).

Pete

Thanks for responses.

It was a very clear day. I just had trouble judging the distance and
speed over the ocean as a non-pilot/aviation-layman. I'm sure we were
at a safe height and I've learned not to trust those perceptions and
didn't worry.

It surprised me how slow planes appear to land and takeoff from a
distance. It looks like about 15-30mph, just barely moving along, but
I know it's much faster.

"Tim923" wrote in message
...
[...]
It surprised me how slow planes appear to land and takeoff from a
distance. It looks like about 15-30mph, just barely moving along, but
I know it's much faster.

Yup. Something that might be helpful to know is that your brain perceives
the speed of a moving object as relative to the size of the object. At a
given speed, a smaller object traverses a distance equal to its length more
quickly than a larger object does. So, at a given speed, your brain will
perceive the smaller object as being faster than the larger object.
Conversely, larger objects appear to be going more slowly.

In spite of knowing of this illusion, one of my favorite things is to watch
especially large airplanes (747 and larger) on final approach. I just love
watching how they seem to just hang in the air in such an improbable way.

Pete

Over clear water that does not have a strong wave pattern
and or solid objects on the surface [boats] or near the
shore line, all pilots have trouble judging altitude.
Seaplane pilots are taught to do a "glassy water" landing
when the surface is ripple free by setting up a landing
attitude and speed over the shore or near boats and then
doing a slow let down under power rather than trying to do a
"normal" landing and flare.

From a porthole window on an airliner, over the ocean,
judging altitude would be very difficult.

Instrument approach procedures for a circling approach
establish minimum circling altitudes so many feet above
known obstacles within an area. The faster the airplane,
the higher the approach category [A,B,C,D and E] and the
larger the turn radius. But if there are no obstacles
within the quadrant in which the airplane is circling to
land, the altitude can be quite low. Many airlines will not
do a circling approach at night, some won't do them at all.


--
James H. Macklin
ATP,CFI,A&P

"Tim923" wrote in message
...
| Thanks for responses.
|
| It was a very clear day. I just had trouble judging the
distance and
| speed over the ocean as a non-pilot/aviation-layman. I'm
sure we were
| at a safe height and I've learned not to trust those
perceptions and
| didn't worry.
|
| It surprised me how slow planes appear to land and takeoff
from a
| distance. It looks like about 15-30mph, just barely
moving along, but
| I know it's much faster.

Tim, this is an excellent observation!

Every pilot is trained on how to deal with a number of common optical
illusions. Flying over water is one of them - it's often quite
difficult to tell how high you are over it, and you are often "tricked"
into thinking that you're lower.

Floatplane pilots account for this effect by keeping the aircraft in a
landing attitude (nose-up) from their approach until they reach the
surface (search for "glassy water" and you'll see). Land-based
airplane pilots use the same technique when performing an emergency
landing in the water.

Your plane wasn't landing in the water, but you caught one of the
optical illusions!

During our training as skydivers we are instructed to release our
canopy from the harness only after entering the water if we are
making a water landing precisely because of this optical illusion.
(rather than cutting away and dropping into the water. We would
release the canopy to avoid becoming entangled in the suspension
lines.) The ocean pretty much looks the same from 10 ft. as it does from
much higher. I suppose it's got something to do with "fractals" and
such.

"Brien K. Meehan" wrote in message
oups.com...
Tim, this is an excellent observation!

Every pilot is trained on how to deal with a number of common optical
illusions. Flying over water is one of them - it's often quite
difficult to tell how high you are over it, and you are often "tricked"
into thinking that you're lower.

Floatplane pilots account for this effect by keeping the aircraft in a
landing attitude (nose-up) from their approach until they reach the
surface (search for "glassy water" and you'll see). Land-based
airplane pilots use the same technique when performing an emergency
landing in the water.

Your plane wasn't landing in the water, but you caught one of the
optical illusions!