Approach speeds for ILS

"Snowbird" wrote in message
om...

the last 3rd of a 6,500 ft runway. Dunno what the tailwind was --
nothing too startling (10-12 kts?)


That is a very significant tailwind for landing; it would not surprise me if
a 10 knot tailwind doubled your landing roll vs. a 10 knot headwind or if
the total landing distance increased between 50% and 100%.


--
Richard Kaplan, CFII

www.flyimc.com

"Richard Kaplan" wrote in message ws.com...
"Snowbird" wrote in message
om...
the last 3rd of a 6,500 ft runway. Dunno what the tailwind was --
nothing too startling (10-12 kts?)

That is a very significant tailwind for landing; it would not surprise me if
a 10 knot tailwind doubled your landing roll vs. a 10 knot headwind or if
the total landing distance increased between 50% and 100%.

Hi Richard,

As far as I could tell, it didn't do a thing to my landing roll.
What it affected, drastically, was the distance it took my plane
to slow to landing speed and consent to stop flying.

I'm very glad I had a CFI who had me try this. Experience is
worth 1000 words. After doing so, I can easily see how an overrun
accident (or loss of control if someone tried to force the plane to
land) could occur on a long, ILS-served runway.

One size definately does not fit all situations for ILS procedures.
I don't think it's a great idea to fly ILS routinely at 60 kts --
as someone pointed out, the margin over stall is much lower and
the configuration changes needed for correction much larger than
at 90 kts. OTOH, a practice of never retarding the throttle
until over the threshold (as I believe Rick Durden suggested)
would IMHO definately be a bad idea on a shorter runway (say
5000-6000 ft) w/ a tailwind.

And my advice to instrument students is: make sure you actually
land out of a good number of ILS in a number of different
circumstances,
preferably ILS in IMC or at night. For that matter, make sure you
land out of a variety of approaches.

Cheers,
Sydney

(Snowbird) wrote:
As far as I could tell, it didn't do a thing to my landing roll.

You may not have noticed the increase, but physics is physics. Most
spam cans touch down at about 50 kts, which means a 10 kt tailwind
increases your touchdown ground speed by 20%. Basic physics says that
will increase your ground roll by 44% for the same amount of braking
effort.

Everybody should try some downwind landings, if only to see just how bad
an idea they are. The problem is how. I don't like doing them at
uncontrolled fields, because you're going against traffic. The best way
is to find a towered airport at a time when there's nobody else around
and ask for the downwind runway.

In article ,
(Snowbird) wrote:
I don't know about a Skyhawk, but FWIW, our former home airport
used to have only 1 ILS, to Rwy 8 which meant if low wx combined with
wind, one might be landing with a tailwind (prevailing winds from
west in these parts). As a training exercise, one time I kept my
speed up to 90 kts over the threshold. I didn't run off the runway,
but I was durn close to my "go around!" point before my plane
decided to quit flying and settle down. I definately landed on
the last 3rd of a 6,500 ft runway. Dunno what the tailwind was --
nothing too startling (10-12 kts?)

As you discovered, a 10-12 knot tailwind is indeed pretty startling.
Most people don't realize just how much effect a relatively small
tailwind has.

I happen to have a Beech S35 POH handy here. For some mumble
combination of weight, temperature, and altitude, the distance over a 50
foot obstacle goes up from 900 to 1400 feet with a 10 kt tailwind. The
graph doesn't go beyond a 10 kt tailwind; I can only assume Beech
figured nobody would want to try a landing with any more :-)

By eye, it looks like the tailwind guide line goes up at about 2-3 times
the slope of the headwind guide line (there's nothing about the shape or
slope of those curves which is model specific).

For linear (de-)acceleration, the distance used goes up by the square of
the ground speed. You normally cross the threshold at maybe 70 kts in a
typical spam can. Crank that up to 90 at the end of an ILS, and you're
using 65% more runway. Add a 10 kt tailwind, and you're using 105% more.

The chart doesn't say anything about how much to increase the distance
by on a wet runway. Or because (as others have pointed out), it's night
and your visual cues suck so your landing isn't as good as it could be.

On Wed, 21 Jan 2004 21:56:10 -0500, Roy Smith wrote:

The
graph doesn't go beyond a 10 kt tailwind; I can only assume Beech
figured nobody would want to try a landing with any more :-)

I believe that at air carrier airports (and, from personal experience, at
BOS) ATC may continue using a runway with up to a ten knot tailwind.

My first tailwind landing ever was done out of an ILS at BOS with about a
ten knot quartering tailwind. But they have long runways (and I needed to
be at the far end anyway to get to the GA ramp).


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Snowbird wrote:

Unfortunately, since many training ILS are done to a missed
approach, landing from an ILS isn't something at which some
instrument pilots get a lot of practice.

That's why I do all my training approaches to a TGL. Which of course, means I
don't get a lot of practice at missed approaches. I guess I ought to mix it up a
little.

Dave
Remove SHIRT to reply directly.

Any thoughts as to why Approach Plates do not list the time for an
approach speed of 75 KIAS?

In a previous article, said:
Any thoughts as to why Approach Plates do not list the time for an
approach speed of 75 KIAS?

Because it's hard to land when you've got a Dash 8 embedded in your
backside?

--
Paul Tomblin http://xcski.com/blogs/pt/
.... industry giant Microsoft Corporation... a company that has become
successful without resorting to software testing...
-- Unknown, rec.humor.funny

On Tue, 20 Jan 2004 18:20:43 -0800, "C J Campbell"
wrote:

I have no problem with flying the ILS at 90 or 100 knots if the ceiling is
well above minimums, but it seems to me that if the ceiling is 200 feet
overcast you ought to be flying the approach slowly enough that you can land
at that speed. You don't need to configure for a short field landing, but
you are not going to slow from 90 knots to 60 in a Skyhawk in only 200 feet
of altitude, especially if you can't risk ballooning back up into the soup.

I would respectfully disagree, although I haven't flown a Skyhawk in years.
However, my Mooney is also an a/c known for being "slippery" with a Vso of
49 kts, a bit faster than the Skyhawk. However, for an approach to
minimums, especially at an airport with "heavy iron", I would view my
limiting speed to be the gear down speed of 105 Kts. (And if I had a newer
Mooney, it would be even faster).

I think an instrument rated pilot should have had the necessary training so
that he can fly the approach at the higher speeds desireable to blend in
with faster traffic -- and not have to worry about "balloning back up into
the soup". Also, most ILS's are into runways of at least 4,000' lengths,
so you don't need to be at 1.2 Vso coming over the threshold (although it
is nice to touch down in the touchdown zone).

Don't forget, at a DA of 200' you will still be about 1/2 mile from the
runway. Given that it's a 4,000' or longer runway, you should be able to
touchdown in the first 1/2 and not run off the far end.

In my Mooney, I have no particular problem with, after reaching a DA of
200' and making the decision to land, lowering the additional two notches
of flaps and slowing speed by the runway threshold (60-65 KIAS -- the
slower speed if there is an operational advantage).

I will say, however, that with a DA of 100', I do not drop the last two
notches of flaps, and I will use about 4,000' of runway if I am using a 105
kt approach speed. But at airports where that may occur, that distance is
usually less than 60% of the total runway length -- again, plenty of room.

So I think that instrument rated pilots who, after all, are legal to fly
into any airport, should have the training and experience to deal with the
faster approach speeds. It really is not that difficult once one starts to
practice.

My most difficult approach, in terms of speed control, came with a request
from PWM approach to "maintain present speed until the (outer) marker". At
the time, my speed was 125 Kts; I was under the hood; and there was an FAA
examiner in the right seat. My gear down speed is 105 kts, flaps 109 kts,
and this approach was being done to a 100' DA with a landing planned. So
it was a matter of coming down, slowing down, and reconfiguring on the way
down. (And yes, I discussed with the examiner the fact that I had not done
something like this before; that I wanted to see how it would work out; and
that if it were the first time doing this procedure in real IMC, my
response would have been "unable").

So I think these instrument pilots should be trained and practiced in
faster approaches.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Ron's thoughts are very realistic and deal with real world scenearios.
All of my instrument students get the experience of flying 140 KT ILS
speeds in my skyhawk at the later points of their training. Of
course, I don't advocate that kind of speed for everyday use, but it
is absolutely no problem getting it stopped on a 5000' runway. There
are only a few ILS's on shorter runways.


On Tue, 20 Jan 2004 23:53:59 -0500, Ron Rosenfeld
wrote:

On Tue, 20 Jan 2004 18:20:43 -0800, "C J Campbell"
wrote:

I have no problem with flying the ILS at 90 or 100 knots if the ceiling is
well above minimums, but it seems to me that if the ceiling is 200 feet
overcast you ought to be flying the approach slowly enough that you can land
at that speed. You don't need to configure for a short field landing, but
you are not going to slow from 90 knots to 60 in a Skyhawk in only 200 feet
of altitude, especially if you can't risk ballooning back up into the soup.

I would respectfully disagree, although I haven't flown a Skyhawk in years.
However, my Mooney is also an a/c known for being "slippery" with a Vso of
49 kts, a bit faster than the Skyhawk. However, for an approach to
minimums, especially at an airport with "heavy iron", I would view my
limiting speed to be the gear down speed of 105 Kts. (And if I had a newer
Mooney, it would be even faster).

I think an instrument rated pilot should have had the necessary training so
that he can fly the approach at the higher speeds desireable to blend in
with faster traffic -- and not have to worry about "balloning back up into
the soup". Also, most ILS's are into runways of at least 4,000' lengths,
so you don't need to be at 1.2 Vso coming over the threshold (although it
is nice to touch down in the touchdown zone).

Don't forget, at a DA of 200' you will still be about 1/2 mile from the
runway. Given that it's a 4,000' or longer runway, you should be able to
touchdown in the first 1/2 and not run off the far end.

In my Mooney, I have no particular problem with, after reaching a DA of
200' and making the decision to land, lowering the additional two notches
of flaps and slowing speed by the runway threshold (60-65 KIAS -- the
slower speed if there is an operational advantage).

I will say, however, that with a DA of 100', I do not drop the last two
notches of flaps, and I will use about 4,000' of runway if I am using a 105
kt approach speed. But at airports where that may occur, that distance is
usually less than 60% of the total runway length -- again, plenty of room.

So I think that instrument rated pilots who, after all, are legal to fly
into any airport, should have the training and experience to deal with the
faster approach speeds. It really is not that difficult once one starts to
practice.

My most difficult approach, in terms of speed control, came with a request
from PWM approach to "maintain present speed until the (outer) marker". At
the time, my speed was 125 Kts; I was under the hood; and there was an FAA
examiner in the right seat. My gear down speed is 105 kts, flaps 109 kts,
and this approach was being done to a 100' DA with a landing planned. So
it was a matter of coming down, slowing down, and reconfiguring on the way
down. (And yes, I discussed with the examiner the fact that I had not done
something like this before; that I wanted to see how it would work out; and
that if it were the first time doing this procedure in real IMC, my
response would have been "unable").

So I think these instrument pilots should be trained and practiced in
faster approaches.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)