Approach speeds for ILS

"Richard Kaplan" wrote
I would say an overrun cannot happen in a 172 on ILS into the wind or with
calm winds as long as the power is cut at decision height. If the airspeed
is high as discussed in this thread and the airplane is on the glideslope,
then the airplane should be within gliding distance of the runway at
decision height.

Yes, that's true. However, I consider an immediate power cut at
decision height to be poor procedure. The normal ILS is flown on a 3
degree glideslope. However, the power-off glide in anything
approaching landing configuration (meaning gear down if retractable
and at least some flaps) will be 7-10 degrees. So a power cut at DH
means a significant pitch change at low altitude. Since most of the
fleet has tractor props and conventional tails, the power cut will
also cause a significant out of trim condition - nose down. In good
vis and with a Skyhawk-class airplane, it's not a big problem. Try
that trick in your C-210 or my PA-30 in less than a mile vis, and
unless you've practiced it extensively and recently, the landing is
goint to be very, very ugly - possibly ugly enough for maintenance
bills. People have been known to drive the gear right through the
wings doing this.

Since my IFR students are either flying high performance singles or
twins or expect to move into them, I just can't see teaching the
procedure you seem to be advocating. I instead teach a gradual power
reduction with retrim, such that the pitch attitude never really
changes and the airspeed bleeds off gradually. Yes, it eats more
runway and on short runway may require a speed reduction on the ILS,
but it seems like a beter tradeoff. Personally, I slow to about
95-100 mph (not kts) on the ILS at about 300 ft, which seems like the
best compromise between retaining the option for a single engine
missed approach and allowing a landing with a tailwind on a short ILS
runway. In a single engine plane, I see no reason not to slow down
further out. I know that an ILS can be flown in a Bonanza at 90 mph
in turbulence - I've seen an instrument student do it.

As far as flying an ILS with a tailwind, I agree that could cause an
overrun. I would also suggest that landing out of an ILS in actual IMC
conditions with a tailwind is an exercise which should be attempted only by
an experienced, advanced IFR pilot and/or with an experienced CFII on-board.

Well, I like to give my student the necessary tools to handle it. Of
course since I don't instruct renters and don't deal with FBO's,
finishing in the minimum allowable 40 hours is not my highest priority
- nor theirs.

In particular, a pilot who is uncomfortable flying a high-airspeed ILS with
a headwind certainly should not attempt a tailwind ILS.

Now that I can agree with. A high speed ILS is certainly something I
consider important. It's just that a high speed ILS and a tailwind
landing on a short runway simply don't mix.

Michael