Winds on approach

I flew yesterday and did some practice approaches, and the winds were
about 20 knots gusting to 26-28. I've flown almost all approaches so
far in a different 172 that had a 180hp conversion. Because of the
winds, I kept almost full cruising power on the descents to try and
maintain my normal 90 kts ground speed for timing and roughly 500fpm
for the ILS.

This plane did have an IFR GPS indicating ground speed, but the one
I've been using for all other approaches didn't, neither DME. The CFI
informed me I should have used known power settings. What are your
thoughts? I'm not sure how I would've known the right power setting,
unless I used what I normally do, and accept the lower ground speed,
then adjust my descent for the ILS to a much lower fpm descent?

On 03/29/07 12:59, kevmor wrote:
I flew yesterday and did some practice approaches, and the winds were
about 20 knots gusting to 26-28. I've flown almost all approaches so
far in a different 172 that had a 180hp conversion. Because of the
winds, I kept almost full cruising power on the descents to try and
maintain my normal 90 kts ground speed for timing and roughly 500fpm
for the ILS.

This plane did have an IFR GPS indicating ground speed, but the one
I've been using for all other approaches didn't, neither DME. The CFI
informed me I should have used known power settings. What are your
thoughts? I'm not sure how I would've known the right power setting,
unless I used what I normally do, and accept the lower ground speed,
then adjust my descent for the ILS to a much lower fpm descent?



I was taught that you should use the proper power settings during the
approach. I would not change these due to my expectation of ground
speed. However, with a higher than standard ground speed, you will
have to adjust your descent rate to maintain the proper glide path.

Here's a question for you to think about. If you have a tail wind which
results in a ground speed of 95 knots, do you need to use the category 'B'
approach minimums?


--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

On Mar 29, 3:59 pm, "kevmor" wrote:
I flew yesterday and did some practice approaches, and the winds were
about 20 knots gusting to 26-28. I've flown almost all approaches so
far in a different 172 that had a 180hp conversion. Because of the
winds, I kept almost full cruising power on the descents to try and
maintain my normal 90 kts ground speed for timing and roughly 500fpm
for the ILS.

Why does ground speed matter? Why does the 500fpm matter?

This plane did have an IFR GPS indicating ground speed, but the one
I've been using for all other approaches didn't, neither DME. The CFI
informed me I should have used known power settings.

I agree.

What are your
thoughts? I'm not sure how I would've known the right power setting,
unless I used what I normally do, and accept the lower ground speed,
then adjust my descent for the ILS to a much lower fpm descent?

What's wrong with a much lower descent rate? All that matters is that
you keep your needles centered. Did you have faster traffic behind
you and you increased speed as a courtesy? I presume you wanted to
maintain 90 kts so that you could time the approach, but aside from it
being an ILS where it doesn't matter, your GPS could tell you where to
go missed if your glide slope goes TU.

It's probably a good idea to know the power settings for some high speed
descent/approach. Like if you are asked to do maximum speed on approach
or something like that. As long as you can handle it and can get the
time right then no problem.

kevmor wrote:
I flew yesterday and did some practice approaches, and the winds were
about 20 knots gusting to 26-28. I've flown almost all approaches so
far in a different 172 that had a 180hp conversion. Because of the
winds, I kept almost full cruising power on the descents to try and
maintain my normal 90 kts ground speed for timing and roughly 500fpm
for the ILS.

This plane did have an IFR GPS indicating ground speed, but the one
I've been using for all other approaches didn't, neither DME. The CFI
informed me I should have used known power settings. What are your
thoughts? I'm not sure how I would've known the right power setting,
unless I used what I normally do, and accept the lower ground speed,
then adjust my descent for the ILS to a much lower fpm descent?

What are your
thoughts? I'm not sure how I would've known the right power setting,
unless I used what I normally do, and accept the lower ground speed,
then adjust my descent for the ILS to a much lower fpm descent?

Exactly. Airspeed is what's crucial for aircraft control. Ground speed
is just used for timing. Adjust the timing. If it's gusty, you might
want a slightly higher airspeed, just like for VFR landings in gusty winds.

Jose
--
Get high on gasoline: fly an airplane.
for Email, make the obvious change in the address.

You are timing your ILS approaches? Any reason for this? I can't find
anything in my 172P book that suggests 90 kts as an approach speed, even in
gusty winds. Seems fast to me.

Bob Gardner

"kevmor" wrote in message
ups.com...
I flew yesterday and did some practice approaches, and the winds were
about 20 knots gusting to 26-28. I've flown almost all approaches so
far in a different 172 that had a 180hp conversion. Because of the
winds, I kept almost full cruising power on the descents to try and
maintain my normal 90 kts ground speed for timing and roughly 500fpm
for the ILS.

This plane did have an IFR GPS indicating ground speed, but the one
I've been using for all other approaches didn't, neither DME. The CFI
informed me I should have used known power settings. What are your
thoughts? I'm not sure how I would've known the right power setting,
unless I used what I normally do, and accept the lower ground speed,
then adjust my descent for the ILS to a much lower fpm descent?

You are timing your ILS approaches? Any reason for this? I can't find
anything in my 172P book that suggests 90 kts as an approach speed, even in
gusty winds. Seems fast to me.

IF one times their ILS, and loses the glideslope, one can often convert
to a localizer approach easily. And approach plates give canned timings
for various speeds, 90 knots is probably the best of the bunch for a
172. Of course that's ground speed, not airspeed.

Jose
--
Get high on gasoline: fly an airplane.
for Email, make the obvious change in the address.

On 03/29/07 14:34, Bob Gardner wrote:
You are timing your ILS approaches? Any reason for this? I can't find
anything in my 172P book that suggests 90 kts as an approach speed, even in
gusty winds. Seems fast to me.

Well ... 90 knots was the speed I was taught to use when flying precision
and non-precision approaches (in the C-172 airplane in which I trained).


Bob Gardner

"kevmor" wrote in message
ups.com...
I flew yesterday and did some practice approaches, and the winds were
about 20 knots gusting to 26-28. I've flown almost all approaches so
far in a different 172 that had a 180hp conversion. Because of the
winds, I kept almost full cruising power on the descents to try and
maintain my normal 90 kts ground speed for timing and roughly 500fpm
for the ILS.

This plane did have an IFR GPS indicating ground speed, but the one
I've been using for all other approaches didn't, neither DME. The CFI
informed me I should have used known power settings. What are your
thoughts? I'm not sure how I would've known the right power setting,
unless I used what I normally do, and accept the lower ground speed,
then adjust my descent for the ILS to a much lower fpm descent?






--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

Conventional wisdom (as I see it) is to execute a miss if you lose the
glideslope, go around, prepare and brief the localizer approach, then do
it. Changing horses in midstream is not wise policy, especially in the
clouds and close to the ground. YMMV, but I'll never teach or advocate the
switch.

Bob Gardner


"Jose" wrote in message
...
You are timing your ILS approaches? Any reason for this? I can't find
anything in my 172P book that suggests 90 kts as an approach speed, even
in gusty winds. Seems fast to me.

IF one times their ILS, and loses the glideslope, one can often convert to
a localizer approach easily. And approach plates give canned timings for
various speeds, 90 knots is probably the best of the bunch for a 172. Of
course that's ground speed, not airspeed.

Jose
--
Get high on gasoline: fly an airplane.
for Email, make the obvious change in the address.

I think I should clarify a couple things from the original post, it
was a headwind on the approach, and I also did a VOR, LOC, and GPS.

If I used the normal power settings, then on the ILS I could just
reduce my descent rate. After reading what you guys said, this should
be fine unless I'm told to fly it faster. But either way, on the ILS
if the needles are centered, you're good.

On the others though, if I kept power at the normal settings with the
headwind, I would've descended to the MDA further out... to me this
seems like an added risk... For timing these, if I didn't have an IFR
GPS or DME (they're new to me), how should I figure the ground speed
for timing?

On Mar 29, 1:16 pm, Mark Hansen wrote:
I was taught that you should use the proper power settings during the
approach. I would not change these due to my expectation of ground
speed. However, with a higher than standard ground speed, you will
have to adjust your descent rate to maintain the proper glide path.

Here's a question for you to think about. If you have a tail wind which
results in a ground speed of 95 knots, do you need to use the category 'B'
approach minimums?