Alternate static on "big iron"?

[Marc Lattoni]

Last night on Discovery Channel there was a story of a Peruvian 757 that
went down because the two static ports had been taped over for cleaning and
not removed. As you might imagine, the airspeed indicator and altimeter gave
erroneous readings and fed the onboard computers erroneous data; after a
series of bizarre warning messages (zero airspeed and "over speed warning"
from the computer) the pilots attempted to correct for contradictory
information and multiple warnings and the plane crashed into the ocean

Do modern airliners not have an alternate static source as on my 172?

Marc

[Peter R.]

Marc Lattoni wrote:

> Last night on Discovery Channel there was a story of a Peruvian 757 that
> went down because the two static ports had been taped over for cleaning and
> not removed. As you might imagine, the airspeed indicator and altimeter gave
> erroneous readings and fed the onboard computers erroneous data; after a
> series of bizarre warning messages (zero airspeed and "over speed warning"
> from the computer) the pilots attempted to correct for contradictory
> information and multiple warnings and the plane crashed into the ocean

I do not know the answer to your question, but an important point about
this crash is that the aircraft was completely flyable and should never
have gone down.

What caused the aircraft to crash was the fact that both pilots were so
distracted attempting to troubleshoot the problem that neither paid any
attention to flying the aircraft. I couldn't tell from your synopsis if
you were aware that the availability of alternate air was most likely
irrelevant to the outcome of this unfortunate accident.

--
Peter

[Brad Z]

Why did they even take off? Isn't airspeed a required call-out and part of
the operating rules for all carriers?

"Marc Lattoni" > wrote in message
news:c3%hc.1386$2q2.192@edtnps84...
> Last night on Discovery Channel there was a story of a Peruvian 757 that
> went down because the two static ports had been taped over for cleaning
and
> not removed. As you might imagine, the airspeed indicator and altimeter
gave
> erroneous readings and fed the onboard computers erroneous data; after a
> series of bizarre warning messages (zero airspeed and "over speed warning"
> from the computer) the pilots attempted to correct for contradictory
> information and multiple warnings and the plane crashed into the ocean
>
> Do modern airliners not have an alternate static source as on my 172?
>
> Marc
>
>

[Capt.Doug]

>"Brad Z" wrote in message > Why did they even take off? Isn't airspeed a
>required call-out and part of the operating rules for all carriers?

The pitot tube was NOT taped over, only the static ports. The runway at
Puerta Plata is fairly level, not much slope. Would the airspeed operate
normally until the altitude changed, which would be after rotation?

D.

[Capt.Doug]

>"Marc Lattoni" wrote in message > Do modern airliners not have an
>alternate static source as on my 172?

The MD-80 does have an alternate static source for each side. It is a
checklist item. However, the crew was distracted at a busy time. Switching
to alternate static probably wouldn't come to mind very quickly.

D.

[Hilton]

Brad Z wrote:
> Why did they even take off? Isn't airspeed a required call-out and part
of
> the operating rules for all carriers?

ASI works just fine on takeoff is the static ports are blocked.

Hilton

[Brad Z]

Woops, I had pitot on my mind!

"Capt.Doug" > wrote in message
...
> >"Brad Z" wrote in message > Why did they even take off? Isn't airspeed a
> >required call-out and part of the operating rules for all carriers?
>
> The pitot tube was NOT taped over, only the static ports. The runway at
> Puerta Plata is fairly level, not much slope. Would the airspeed operate
> normally until the altitude changed, which would be after rotation?
>
> D.
>
>

[tom418]

On the B727, the Captain's or F/O's static sources are selectable from
Normal to "Alternate", which would provide the static instruments with
static air which is used for the Mach Airspeed Warning and Pressurization
systems

"Marc Lattoni" > wrote in message
news:c3%hc.1386$2q2.192@edtnps84...
> Last night on Discovery Channel there was a story of a Peruvian 757 that
> went down because the two static ports had been taped over for cleaning
and
> not removed. As you might imagine, the airspeed indicator and altimeter
gave
> erroneous readings and fed the onboard computers erroneous data; after a
> series of bizarre warning messages (zero airspeed and "over speed warning"
> from the computer) the pilots attempted to correct for contradictory
> information and multiple warnings and the plane crashed into the ocean
>
> Do modern airliners not have an alternate static source as on my 172?
>
> Marc
>
>

[Michelle P]

Marc,
The Canadair Regional Jet has a three static sources. They are
selectable from normal to alternate. This usually cross connects the
Captains to the F/O and vice versa. The third one is independent for the
Mach speed transducer and the Cabin Pressure Acquisition module.
It would be safe to assume that if one or more of the static port was
taped over for painting then all of them were taped over.
Our Turbo Props do not have a selectable static source. They do have
selectable Air Data computers though.
Michelle

Marc Lattoni wrote:

>Last night on Discovery Channel there was a story of a Peruvian 757 that
>went down because the two static ports had been taped over for cleaning and
>not removed. As you might imagine, the airspeed indicator and altimeter gave
>erroneous readings and fed the onboard computers erroneous data; after a
>series of bizarre warning messages (zero airspeed and "over speed warning"
>from the computer) the pilots attempted to correct for contradictory
>information and multiple warnings and the plane crashed into the ocean
>
>Do modern airliners not have an alternate static source as on my 172?
>
>Marc
>
>
>
>

--

Michelle P ATP-ASEL, CP-AMEL, and AMT-A&P

"Elisabeth" a Maule M-7-235B (no two are alike)

Volunteer Pilot, Angel Flight Mid-Atlantic

Volunteer Builder, Habitat for Humanity

[C J Campbell]

"Marc Lattoni" > wrote in message
news:c3%hc.1386$2q2.192@edtnps84...
>
> Do modern airliners not have an alternate static source as on my 172?
>

Modern airliners have multiple static ports, but they do not have one like
your 172. The alternate static port in your 172 uses cabin air. Airliners
are pressurized, so an alternate static port like on the 172 would be
worthless.

[Andrew Sarangan]

"Capt.Doug" > wrote in message >...
> >"Marc Lattoni" wrote in message > Do modern airliners not have an
> >alternate static source as on my 172?
>
> The MD-80 does have an alternate static source for each side. It is a
> checklist item. However, the crew was distracted at a busy time. Switching
> to alternate static probably wouldn't come to mind very quickly.
>
> D.

Where is the alternate static port vented? It can't be vented to the
cockpit in a pressurized aircraft, no?

[Peter Duniho]

"C J Campbell" > wrote in message
...
> Modern airliners have multiple static ports, but they do not have one like
> your 172. The alternate static port in your 172 uses cabin air. Airliners
> are pressurized, so an alternate static port like on the 172 would be
> worthless.

I wonder. After all, the time you'd really need the alternate static port,
you'd be low enough for the cabin to be left unpressurized. More than
likely, the pilots would notice the need for alternate static reference
before they climbed above an altitude where pressurization is required.

I can believe that pressurized transport category airplanes don't bother
with a cabin-vented alternate static port, as a matter of the designers not
bothering to provide that. But I don't see any reason why that wouldn't be
a feasible safety feature.

Just select the cabin-vented alternate static port, and allow the cabin to
climb to ambient pressure altitude.

Pete

[John Galban]

"Marc Lattoni" > wrote in message news:<c3%hc.1386$2q2.192@edtnps84>...

>
> Do modern airliners not have an alternate static source as on my 172?
>

They have alternate static, but it's not as simple as the one on
your 172. If yours is like most spamcan alternate static sources, it
opens the static system to the cabin air. Simple and almost
foolproof, but that sort of system wouldn't work on a pressurized
airplane. The artificially high cabin pressure would generate
erroneous readings. A pressurized airplane would have to have its
alternate static source open to the outside air (where it can be taped
over).

John Galban=====>N4BQ (PA28-180)

[David CL Francis]

On Fri, 23 Apr 2004 at 02:55:09 in message
<hA%hc.5284$0u6.1143009@attbi_s03>, Brad Z > wrote:

>Why did they even take off? Isn't airspeed a required call-out and part of
>the operating rules for all carriers?

Because the airspeed read almost normal until they started to climb I
believe.
--
David CL Francis

[Capt.Doug]

>"Andrew Sarangan" wrote in message > Where is the alternate static port
>vented? It can't be vented to the cockpit in a pressurized aircraft, no?

The alternate static port is inches away from the primary static port. Now
that you mention it, if one was taped over, the other would likely be taped
over also.
D.

[StellaStar]

> on Discovery Channel there was a story of a Peruvian 757 that
>went down because the two static ports had been taped over for cleaning

That and many other stories are recounted in a book (I got it as a gift) called
"The Black Box" and there appears to be a new edition out. Many of the stories
have transcripts of radio conversations, and there's background information on
the crews and circumstances as well as the information later gathered about the
incidents, many of which are unfortunately fatal crashes.

The events often seem to have been avoidable and in some cases you'll read it
shaking your head over the carelessness or lack of communication that clearly
led to poor decisions. I'd recommend it, though it's depressing reading and
you should never let your nonpilot friends read it!

http://www.amazon.com/exec/obidos/tg/detail/-/0688158927/103-3567979-74566
41?v=glance