Freezing rain: What do the airline pilots do?

In watching a freezing rain/snow storm move from the midwest up to the
northeast US today, I again wonder how the airlines deal with freezing
rain. Are many flights canceled during a freezing rain storm or is it
business as usual?

Does a deicing on the ground and anti-icing equipment on the aircraft
provide the protection needed to fly into or out of freezing rain
conditions for the airline aircraft?

--
Peter

I am not an expert on this, but I'll give this a question a stab...

"Peter R." writes:
In watching a freezing rain/snow storm move from the midwest up to the
northeast US today, I again wonder how the airlines deal with freezing
rain. Are many flights canceled during a freezing rain storm or is it
business as usual?

"It depends". Freezing rain can have several effects:

1. icing up runways and taxiways. It takes time for airports to
clean off the ice. This can mess with commercial flights.

2. coating parked or taxiing planes with ice. The ice needs to be
removed, which takes time. This can gum up schedules.

3. getting ice on planes as they fly. Most commercial jets fly
really fast, which has two effects: first, it means that the planes
will fly through the freezing levels quickly (and up higher where it
is too cold for ice accumulation), so they don't pick up much ice.
Also, the wings and control surfaces get heated by the passing air,
and are warm enough that ice doesn't tend to stick to the plane. So
in many circumstances the jet can just fly through the freezing
conditions and not worry about it.

Does a deicing on the ground and anti-icing equipment on the aircraft
provide the protection needed to fly into or out of freezing rain
conditions for the airline aircraft?

In many cases, yes (it depends on how severe the icing conditions
are). The presence of icing conditions would make the pilots be much
more careful about watching out for ice, but otherwise everything is
routine.

Now, many of the people in this group (including me) fly GA planes,
which usually fly lower and slower than commercial jets. For these
planes icing is a much more serious problem, and so we can't fly in
the same weather as commercial jets.

Think of it this way -- your car has windshield wipers. In light or
moderate rain, they let you drive in the weather without any problem.
But in an absolute downpour they may not be able to keep up, and so
you are better off pulling over and waiting for the rain to pass...

Chris

Christopher Brian Colohan wrote:

Think of it this way -- your car has windshield wipers. In light or
moderate rain, they let you drive in the weather without any problem.
But in an absolute downpour they may not be able to keep up, and so
you are better off pulling over and waiting for the rain to pass...

When I was recently sitting on an airliner waiting to take off, we were
told that we couldn't take off because at the time there were both
freezing rain and ice pellets. We were told that they could take off if
either went away, but not as long as both continued. They claimed it
was an FAA requirement.
--
Gene Seibel
Tales of Flight - http://pad39a.com/gene/tales.html
Because I fly, I envy no one.

Christopher Brian Colohan wrote:

first, it means that the planes
will fly through the freezing levels quickly (and up higher where it
is too cold for ice accumulation), so they don't pick up much ice.

Thanks, Chris. Regarding the above, that may be true for departing
aircraft, but what about aircraft on approach to a busy airport? It is
certainly probable that these aircraft may be vectored around at lower
altitudes for many minutes at slower speeds. I would imagine that if this
occurs in heavy freezing rain this could be a real problem, no?


--
Peter

Peter R. wrote:

Thanks, Chris. Regarding the above, that may be true for departing
aircraft, but what about aircraft on approach to a busy airport? It is
certainly probable that these aircraft may be vectored around at lower
altitudes for many minutes at slower speeds. I would imagine that if this
occurs in heavy freezing rain this could be a real problem, no?


ATC is very good about working with pilots to get out of severe ice
when/if it happens. AFAIK no anti-ice system on any aircraft will keep
up with severe icing so the only solution is get outta Dodge. This
situation happened to me once on a charter trip in the Pilatus. We were
being vectored for an ILS and were outside the marker being turned onto
final and I noticed the buildup on the wings. Seeing as that's a pretty
busy time we set the boots to cycle automatically, opened the inertial
separator (the engine intake is always heated) prop heat on, and flew
the approach at normal speed. Fortunately the accumulation wasn't
anything the ice systems couldn't handle.

"Peter R." wrote in message
...
Christopher Brian Colohan wrote:

first, it means that the planes
will fly through the freezing levels quickly (and up higher where it
is too cold for ice accumulation), so they don't pick up much ice.

Thanks, Chris. Regarding the above, that may be true for departing
aircraft, but what about aircraft on approach to a busy airport? It is
certainly probable that these aircraft may be vectored around at lower
altitudes for many minutes at slower speeds. I would imagine that if this
occurs in heavy freezing rain this could be a real problem, no?


Bleed air from the engines is used to warm things up enough to unstick the
ice on the heavy stuff. Lighter air craft use things like inflatable boots
on the leading edge of the wings and props to mechanically knock the ice
off. Or, Fluid systems are used that spread de-icing fluid onthe wings and
props during flight. Electric heat has been used for propellors.

See also
http://en.wikipedia.org/wiki/Ice_protection_system

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

"Peter R." writes:
Christopher Brian Colohan wrote:

first, it means that the planes
will fly through the freezing levels quickly (and up higher where it
is too cold for ice accumulation), so they don't pick up much ice.

Thanks, Chris. Regarding the above, that may be true for departing
aircraft, but what about aircraft on approach to a busy airport? It is
certainly probable that these aircraft may be vectored around at lower
altitudes for many minutes at slower speeds. I would imagine that if this
occurs in heavy freezing rain this could be a real problem, no?

(speaking from a complete lack of experience...) I also imagine that
this could be a problem, and I would guess that the solution is "don't
do that". If a plane is picking up ice, the solution is to leave the
icing conditions -- either climb or descend. I'm sure ATC would allow
a plane to do this if a request was made.

Chris

On the ground, freezing rain does to an airplane just what
it does to your car. The entire airplane is clobbered.
Doors won't open or close properly. Flaps, ailerons and
spoilers may be frozen in position.

Before take-off, airlines spray boiling hot water on the
airplane (180° or so) to remove the snow and ice, then they
switch to a heated mixture of water and anti-freeze to keep
any ice from accumulating on the airplane during the time it
takes to taxi and take-off. As rain/snow fall on the plane
and melt, the antifreeze solution become diluted and the
water will begin to freeze in hinges and such.

The FAA parts 121 and 135 do not allow take-off in certain
extreme icing conditions, but pilots have the authority to
NOT GO even when the regulation might allow.

In-flight, the aircraft anti-and de-icing systems will
handle typical icing encounters, but severe icing is defined
as ice that build TOO FAST for even the equipment to handle.

see
http://ecfr.gpoaccess.gov/cgi/t/text...1.21&idno= 14
and
http://ecfr.gpoaccess.gov/cgi/t/text...1.14&idno=1 4



"Christopher Brian Colohan" wrote in
message .. .
| "Peter R." writes:
| Christopher Brian Colohan wrote:
|
| first, it means that the planes
| will fly through the freezing levels quickly (and up
higher where it
| is too cold for ice accumulation), so they don't pick
up much ice.
|
| Thanks, Chris. Regarding the above, that may be true
for departing
| aircraft, but what about aircraft on approach to a busy
airport? It is
| certainly probable that these aircraft may be vectored
around at lower
| altitudes for many minutes at slower speeds. I would
imagine that if this
| occurs in heavy freezing rain this could be a real
problem, no?
|
| (speaking from a complete lack of experience...) I also
imagine that
| this could be a problem, and I would guess that the
solution is "don't
| do that". If a plane is picking up ice, the solution is
to leave the
| icing conditions -- either climb or descend. I'm sure ATC
would allow
| a plane to do this if a request was made.
|
| Chris

On the ground, de-icing is done by vehicles at the gate or by the aircraft
taxiing to an area set up for mulitple de-icing. Fluid is sprayed on the
aircraft which removes the ice and offers protection for a short while.
Crews have charts which evaluate the type of fluid used, the degree of icing
condition, etc,, and provide timing. The aircraft has to depart before that
time is up or de-ice again.

Most airline aircraft use pneumatic heat that is channeled to the leading
edges of wings, horizontal & vertical stabilizers, and other areas that are
vulnerable to icing. Other areas are electrically heated. While in icing
conditions engine and air foil anti-icing is turned on. Freezing rain can
only occur when a temperature inversion is present. That is, the air above
must be above freezing and rain coming from that altitude falls through
colder, freezing air. Normally this doesn't happen since temperatures are
normally colder at higher altitudes.

Icing can occur at any altitude as long as icing conditions exist but it is
rare at the cruising altitudes of commercial jets.

--
Darrell R. Schmidt
B-58 Hustler Web Site
http://members.cox.net/dschmidt1/
Cadet Class 55-I Web Site
http://pilotclass55india.org/
"Peter R." wrote in message
...
In watching a freezing rain/snow storm move from the midwest up to the
northeast US today, I again wonder how the airlines deal with freezing
rain. Are many flights canceled during a freezing rain storm or is it
business as usual?

Does a deicing on the ground and anti-icing equipment on the aircraft
provide the protection needed to fly into or out of freezing rain
conditions for the airline aircraft?

--
Peter

Jim Macklin wrote: brevity snip

Before take-off, airlines spray boiling hot water on the
airplane (180° or so) to remove the snow and ice, then they
switch to a heated mixture of water and anti-freeze to keep
any ice from accumulating on the airplane during the time it
takes to taxi and take-off. As rain/snow fall on the plane
and melt, the antifreeze solution become diluted and the
water will begin to freeze in hinges and such.

Light frost on the aircraft prompted our pilot in SLC to de-ice.
One plane ahead of us: total delay ~45 minutes.

http://i16.tinypic.com/4gr9p8n.jpg
http://i10.tinypic.com/2rcu9sh.jpg
-----

- gpsman