Jefferson City pilots took plane to maximum altitude

Wolfgang Kemper wrote in news:d8mpdd$ent$1
@home.itg.ti.com:

John Galban wrote:

Bucky wrote:

For example, the top speed of a car could be 120 mph, but it would be
dangerous to drive it at that speed because a sudden movement in the
steering wheel could cause the car to flip over.


This can happen at 75 mph or at 50 mph. What's so magic about 120
mph? If you're point is that driving a car is dangerous, I agree. If
you're trying to make some analogous connection to flying a plane at
it's service ceiling, you missed the boat (car, plane...).

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

Little notice from a German "Autobahn" driver:
I had a Alfa Romeo where I felt very comfortable even with 150 mph
and I had a Jaguar where 120mph was nice but at 150mph I had the
impression to became instable.
I pushed a Chevy Blazer to 100 mph and was afraid to kill myself.
Everything is relative , some dudes manage to flip over at 30mph , I
have seen this last December here in Dallas, and with the right car and
environment even 200 mph are safe.

Sorry way OT.

I agree. It all depends on the vehicle, the driver, and probably
more importantly, the road conditions.

I have a Harley Sportster ('86 883) and I've pushed it over the
century mark. On a good clean road it's rock solid. Then again,
I've been nearly dumped by a railroad crossing in bad shape at
only 30mph. Damn near jolted the handle bars out of my hands.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism

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Sed quis custodiet ipsos Custodes?

"Bucky" wrote in message
oups.com...
I'm not blaming the pilots. I just want to find out if flying a plane
at its maxmimum operating altitude is standard practice, or if it's
considered dangerous.

It's not considered dangerous.

For example, the top speed of a car could be 120 mph, but it would be
dangerous to drive it at that speed because a sudden movement in the
steering wheel could cause the car to flip over.

A sudden movement in the steering wheel could cause the car to flip over at
60 mph, depending on the nature of the movement (which would be true at 120
mph as well). Likewise, an airplane can be crashed from practically any
altitude or airspeed.

Even with your reference, it's not clear what is meant by "maximum
altitude", but assuming that marketing document is referring to the
certified ceiling of the aircraft (as described on the type certificate),
the aircraft should be expected to fly safely all the way up to, and
including, that altitude. This would include expecting the engine design to
tolerate operation at that altitude, without stoppage.

I can see no justification for expecting the pilots to limit themselves to a
lower altitude. The CVR may indicate a less-than-professional approach to
their flying (one normally selects a cruise altitude for reasons other than
entertainment, for example ), but there's no indication that they did
anything wrong operationally.

Of course the article says nothing about whether they stopped at 41,000'.
It sure sounds as though they got to FL410, and then just cruised at that
altitude. But if they had tried to climb higher, that might have presented
a problem. Until there's evidence they did so, however, the "head of the
Air Travelers Association" has no basis for his comments. All
experimentation had presumably been done previously, during the
certification of the airplane. All the pilots were doing is operating the
airplane within the limits determined during certification.

It will be interesting to see what the ultimate determination of the engine
failures is. It could be one of at least three causes, including:

* Pilots exceeded certified ceiling (ie they didn't stop climbing at
41,000')

* Poor maintenance resulted in engines that no longer performed to
certified standards

* Erroneous or (even worse) fraudulent data used during certification
resulting in an aircraft that had never actually been tested at the designed
and certified ceiling of 41,000'

It may turn out to be something else entirely.

Perhaps when the final NTSB report is released, information along those
lines will be provided. Until then, I think it's premature for anyone to be
criticizing any party, the pilots or otherwise, for any liability in the
accident. It could even turn out that, in the end, it was all just an
accident.

Pete

Maximum altitude is usually based on pressure differential...the difference
between ambient pressure outside the aircraft vs cabin pressure...the
engines don't come into the equation. I have had a Lear 23 up to FL43, which
is/was its maximum altitude. The Lear's manual contained a restart envelope,
just in case one or both engines failed...it involved gliding down to at
least 12000 feet before a restart was attempted (the atmosphere must contain
enough oxygen to support combustion).

Bob Gardner

"Bucky" wrote in message
oups.com...
http://news.yahoo.com/s/ap/plane_crash_investigation

I think this was reported a month ago as well, but there was another
round of news releases today stating that the pilots took their
Bombardier CJR200 to its maximum altitude of 41,000 ft. Afterwards,
both engines failed and they crashed before reaching an airport.

Of course, the pilots should not have experimented around, but is it
dangerous to take a plane to its max altitude? When the engineers
specify a maximum altitude, doesn't it still have to be safe at that
altitude?

Bob Gardner wrote:
Maximum altitude is usually based on pressure differential...the difference
between ambient pressure outside the aircraft vs cabin pressure...the
engines don't come into the equation.

So you're saying that the engines could operate at an even higher
altitude. It's just that the cabin pressure could not be maintained?

No. A pressurized airplane is like a balloon....more pressure inside than
out. If the pressure differential overcomes all of the safety features meant
to avoid such a disaster, there would be a blowout at the weakest
point...maybe a window, maybe a door seal, who knows? OTOH, if "cabin
pressure could not be maintained" means an explosive decompression to you,
then your statement would be correct.

What it would take to keep the fire burning in the engines is something else
again...there has to be a point at which combustion fails. Obviously, the
two fun-seekers lost their engines. Neither you nor I know why. I can't
understand the restart problem, though.

An aspect of max altitude that has not been mentioned here is the "coffin
corner" where Mach buffet and stall speed come together. Nothing to do with
engine failure, but a consideration when flying high.

Bob Gardner

"Bucky" wrote in message
oups.com...
Bob Gardner wrote:
Maximum altitude is usually based on pressure differential...the
difference
between ambient pressure outside the aircraft vs cabin pressure...the
engines don't come into the equation.

So you're saying that the engines could operate at an even higher
altitude. It's just that the cabin pressure could not be maintained?

"Bob Gardner" wrote
An aspect of max altitude that has not been mentioned here is the
"coffin corner" where Mach buffet and stall speed come together.
Nothing to do with engine failure, but a consideration when flying
high.

True..and "coffin corner" is weight dependant.
The 41,000' limit for the B-707 was determined by
the time required to execute an emergency descent
to 14,000'.

Bob Moore

"Bucky" wrote in message
oups.com...
So you're saying that the engines could operate at an even higher
altitude. It's just that the cabin pressure could not be maintained?

It really just depends on the aircraft. Every airplane has a variety of
limits with respect to their operation. For many of those limits, there are
actually a variety of potential limiting factors resulting in those limits,
with usually only one being the *actual* limiting factor.

For a pressurized aircraft, the certified ceiling could be due to the
pressurization system or due to some engine limitations, or due to something
else entirely (like stall speed, for example, where "stall" refers to an
aerodynamic limitation having nothing to do with the engines). You'd have
to consult the aircraft designer to learn which it was.

Pete

I have been in one on my old employers CRJ-200s at 41000 feet and I can
tell you they fly fine. We we repositioning and want to get home. I
un-fortunately was riding in the jump seat and not the left seat. :-(
Michelle

Bucky wrote:

http://news.yahoo.com/s/ap/plane_crash_investigation

I think this was reported a month ago as well, but there was another
round of news releases today stating that the pilots took their
Bombardier CJR200 to its maximum altitude of 41,000 ft. Afterwards,
both engines failed and they crashed before reaching an airport.

Of course, the pilots should not have experimented around, but is it
dangerous to take a plane to its max altitude? When the engineers
specify a maximum altitude, doesn't it still have to be safe at that
altitude?

"Bucky" wrote in message
oups.com...
http://news.yahoo.com/s/ap/plane_crash_investigation

I think this was reported a month ago as well, but there was another
round of news releases today stating that the pilots took their
Bombardier CJR200 to its maximum altitude of 41,000 ft. Afterwards,
both engines failed and they crashed before reaching an airport.

Of course, the pilots should not have experimented around, but is it
dangerous to take a plane to its max altitude? When the engineers
specify a maximum altitude, doesn't it still have to be safe at that
altitude?

When an aircraft's operating limitats are established, the idea is that you
should be able to safely operate the aircraft within those limitations.
Exceed the limitats beyond a certain safety factor, and bad things may
happen.

The question I have not seen answered is whether 41,000' is outside the
normal operating limits for the aircraft, particularly for its engines. If
so, these guys were playing test pilot, if not, there was nothing wrong,
foolish, dangerous, careless, or irresponsible with taking the aircraft to
that altitude.

KB

"Kyle Boatright" wrote in message
...

"Bucky" wrote in message
oups.com...
http://news.yahoo.com/s/ap/plane_crash_investigation

I think this was reported a month ago as well, but there was another
round of news releases today stating that the pilots took their
Bombardier CJR200 to its maximum altitude of 41,000 ft. Afterwards,
both engines failed and they crashed before reaching an airport.

Of course, the pilots should not have experimented around, but is it
dangerous to take a plane to its max altitude? When the engineers
specify a maximum altitude, doesn't it still have to be safe at that
altitude?

When an aircraft's operating limitats are established, the idea is that
you should be able to safely operate the aircraft within those
limitations. Exceed the limitats beyond a certain safety factor, and bad
things may happen.

The question I have not seen answered is whether 41,000' is outside the
normal operating limits for the aircraft, particularly for its engines.
If so, these guys were playing test pilot, if not, there was nothing
wrong, foolish, dangerous, careless, or irresponsible with taking the
aircraft to that altitude.

KB

My apologies. I made a too-quick correction and changed limitations to
limitats, instead of limits...