White over white is alright?

"G.R. Patterson III" wrote in message ...


Peter Duniho wrote:

True enough. I have, for some time now, included as part of my new
passenger preflight briefing the warning that things will get VERY quiet
right near the end of the flight, as power is reduced for landing.

Yeah. I forgot to do that on a Young Eagles flight a couple weeks ago. The
kids got a little worried there at first.

Gee, you had more squemish kids. Mine had a blast even after the Navion
blew a cylinder and started shaking itself to death and the persuant emergency
landing. They were ready to go up again.

"Kiwi Jet Jock" wrote in message
...

Additionally, some might be interested in doing some experiments dumping
flap during a simulated engine failure on approach to work out at what
height the additional height loss (in dumping the flap) is (more than)
compensated by the increased gliding range.


Interesting. "Dumping", you mean retracting, right? The idea being to
reduce the drag & preserve energy to extend the glide distance?

I'd have thought that above 'best glide' speed, you'll always extend your
glide distance - without any associated additional height loss if you
pitch to maintain airspeed - by retracting flaps. After all, at constant
speed, you'll be cleaner and dissipating less energy -- energy which
can only come from the loss of your (2.m.g.h) potential energy as you
descend. (If this wasn't the case, the POH would tell you to add flaps
to configure for best glide).

Below best glide, things aren't as clear. It may be that the induced drag
with flaps out is less than that when clean. Well, for low setting flap
settings, anyway. In the worse case, you should only need to get back to
best glide, which means the additional height loss will be the potential
energy needed to increase your speed.

0.5 * m * (v'-v)**2 = 2*m*g*h
(v'+v)*(v'-v) = 4*g*h

so for v' (best glide) = 70knots = 120 ft/sec, v (approach speed) =
60 knots = 100 ft/sec, height loss works out at about 35 ft.

Now in my 182, I typically maintain 70 knots (which happens to be
my best glide speed) until short-ish final, so I know exactly what I'll
be doing if the engine conks out (assuming I've been obliged to take
the 'grand tour' behind someone, or I'm coming in on the final 1/2 mile
or so of an ILS). I slow to 60 when I'm pretty sure I'll make the
airport property, if not the runway itself, so exactly what the optimum
response to an engine failure might be in the low speed régime doesn't
concern me that much.

Of course, with a headwind, you'd normally trim for slightly more than
best glide speed to increase your range. But that's another topic.

On Mon, 07 Jul 2003 21:51:32 GMT, "Randy Wentzel"
wrote:

First, I would like to say thank you to this group and the folks over at
rec.aviation.student for being such a valuable, mature resource. It's hard
to find that within Usenet now-a-days.

OK, on to my question:

During my flight training, I was taught that it's best to come in high "so
that the runway is guaranteed throughout the pattern," even if the engine
were to fail. This is fine and dandy, but I always come in with the VASI
indicating "white over white" and with the tower noting my position to other
aircraft in the pattern as "the Cessna on a short, high final."


I feel completely comfortable with my approaches and *usually* flare before
the numbers. VASI approaches now seem too shallow for a visual approach.

OK...my take...

I see nothing wrong with coming in above the VASI glide slope...in the
day time and at a strip you know well.

Night time and unknown strips are another matter.
Gainsville Ga is a good example. Looking at the AFD you will find the
runways are plenty long so unless you are one of those who adds "a
little extra" there should be no danger of overshooting...BUT if you
come in after dark and without the VASI guidance for the one runway (I
forget which now) it will be an interesting experience. That one
runway is considerably higher in the center than at the ends. Using
the VASI gives you guidance right to the touchdown area.
Goodland KS is another, but just the opposite of Gainsville. Here the
middle of the runway is considerably lower than either end.

I'm assuming you normally use a short strip to usually flare before
the numbers.

"I think" flight instructors who teach "landing on the numbers" do a
great disservice to their students. It may not be their goal, but it
ingrains what can be a dangerous habit and one that is really annoying
at large airports. They can achieve the same results by picking a
spot, such as the touchdown zone and going for precision.

If it's a short strip, by all means use short field technique, but on
longer strips landing on the numbers removes a safety cushion. The
same one that "staying within gliding distance" provides. There are
techniques for getting rid of altitude, but none that will add more
distance when you have neither the speed nor altitude to trade.

I fly high performance and rarely fly the VASI during the day. I
rarely fly a stabilized approach during the day, but I fly both at
night. IF I have passengers who are unfamiliar with flying, I fly a
stabilized approach with nice gentle turns and do fly the VASI.

One other comment...The VASI may seem shallow (and it is compared to
most VFR finals), but it should bring you to the runway at the
touchdown zone where you should be touching down, not the numbers.

Don't land long on short strips and don'l land short on long strips.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)


What are your feelings on this?

Best,

Randy

On Tue, 8 Jul 2003 12:48:39 -0700, Peter Duniho
wrote:
A high approach is generally not a problem. Some fields, such as Boeing
Field in Seattle, require you to fly the glideslope. There they want you
to
stay on the VASIs in order avoid traffic conflicts with helicopters.

For my information where and how is this indicated?

Typically, the ATIS carries a phrase along the lines of "pilots are reminded
to fly the VASI" or something like that (while I used to fly there
frequently, it's been a couple of years so I don't recall the exact
wording). They don't actually explain WHY the request is being made, but it
is because of the helicopter traffic.


This is news to me. I've never been chewed out by a BFI controller
for making a steep approach. I always interpreted the phrase to mean
don't go below the VASI.


Morris