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.