Bush to consider shutting down GPS in extreme emergency

  • Thread starter Thread starter Fred
  • Start date Start date
Not really. They are in intermediate orbits, way below the
geostationary orbit.
Click to expand...

But they are also in "very high orbits" by any reasonable definition.
They are in a 12 hour orbit - one might call that "geosynchonous/2" at
around 12,000 miles. That's at least three earth radii above the
surface. A compass, ruler, pencil and a little drawing should be
enough convince you that this is high enough to cover most of a
hemisphere.

Ed
 
I would think that the only sensible solution when you're higher
or hotter is to load the plane only so much that you can still
climb on any one engine.
Click to expand...

In the US, you're required to do that if you fly it IFR. The requirement
is to be able to climb at 50 ft/min to 5,000ft or the MEA, whichever is
greater, with the critical engine inoperative. That can be a problem for
many light twins, and the payload has to be cut back considerably,
depending on the temperature, of course.

Note, this isn't a certification requirement, it's an operational
requirement, and only IFR.
 
I wouldn't.
If an engine quits right at takeoff in a light twin, shut down
the other one.
But if it quits anywhere else, it gives you a lot more time to
select a place to land, even if you cannot maintain altitude.
of some sort.

Stan, Alan,

thanks for the precise information.
Click to expand...

The only problem with this "precise information" is that it's
simply WRONG.

"Starting with the obvious, large aircraft certified under FAR
Part 25 have certain redundancies and required performance
capabilities that are not required for light aircraft certified
under Part 23 or the old CAR 3, as most of the fleet is. For
example, an engine failure on takeoff in a light piston twin
does not guarantee the pilot any climb performance--none. All it
offers is the opportunity to make a decision. In Part 25
aircraft, which includes some business jets, there is a required
level of performance that gives the pilot something to work
with."

Read it again: "[A]n engine failure on takeoff in a light piston
twin does not guarantee the pilot any climb performance--none."

http://www.aopa.org/asf/asfarticles/sp9710.html

Be careful of the information you get on usenet.
 
Mxsmanic said:
Alan Browne writes:




It's your true position with respect to the GPS datum, for all practical
purposes.
Click to expand...

"truth" in navigation means a point. There is almost no way that the average
position from GPS over a very, very long period will converge on that point.
The average will wander around near it.

"practical purposes" would put that average position within a quarter meter,
maybe less. But that is not a 'truth' position.
 
Mxsmanic said:
Alan Browne writes:




Common-view GPS time transfer, for example:

http://www.boulder.nist.gov/timefreq/time/commonviewgps.htm
Click to expand...

Of course. It uses GPS. So it could hardly be available before GPS now, could it?

Through communications and accurate clocks at each end of the communications
pipe, a converged time solution within microseconds (if not better) is quite
feasible. I belive SONET among other high speed nets relied on this to
microsecond level, and other networks to higher levels.

But all this is of course to avoid higher cost clocks at each end. With higher
accuracy atomic clocks, syncronized from a travelling master, accuracy and
syncronization could be attained at ever increasing accuracy. At a cost.
 
[email protected] (Iolaos) wrote in
thanks for the precise information.
Click to expand...

The only problem with this "precise information" is that it's
simply WRONG.

"Starting with the obvious, large aircraft certified under FAR
Part 25 have certain redundancies and required performance
capabilities that are not required for light aircraft certified
under Part 23 or the old CAR 3, as most of the fleet is. For
example, an engine failure on takeoff in a light piston twin
does not guarantee the pilot any climb performance--none. All it
offers is the opportunity to make a decision. In Part 25
aircraft, which includes some business jets, there is a required
level of performance that gives the pilot something to work
with."

Read it again: "[A]n engine failure on takeoff in a light piston
twin does not guarantee the pilot any climb performance--none."

http://www.aopa.org/asf/asfarticles/sp9710.html

Be careful of the information you get on usenet.
Click to expand...

Which is what I said. Part 23 requires that the aircraft demonstrate a
climb with the critical engine inoperative and the gear and flaps
retracted. It does not specify that it has to do that under all
conditions, nor with the gear down. The manufacturer can demonstrate it
with only a pilot aboard and a few minutes' fuel. It just has to have a
chart with the conditions under which it can and can't climb available.
Read my post a little closer.
 
Alan said:
Of course. It uses GPS. So it could hardly be available before
GPS now, could it?
Exactly.

Through communications and accurate clocks at each end of the communications
pipe, a converged time solution within microseconds (if not better) is quite
feasible.
Click to expand...

Microseconds aren't good enough today.
But all this is of course to avoid higher cost clocks at each end. With higher
accuracy atomic clocks, syncronized from a travelling master, accuracy and
syncronization could be attained at ever increasing accuracy. At a cost.
Click to expand...

That would not be cost-effective.
 
Alan said:
"truth" in navigation means a point. There is almost no way that the average
position from GPS over a very, very long period will converge on that point.
The average will wander around near it.
Click to expand...

That depends on a number of things. In any case, it could come very
close indeed, as close as any other form of surveying might place it.
"practical purposes" would put that average position within a quarter meter,
maybe less. But that is not a 'truth' position.
Click to expand...

I'd expect a few centimetres over time, depending on various things.
 
In the US, you're required to do that if you fly it IFR. The requirement
is to be able to climb at 50 ft/min to 5,000ft or the MEA, whichever is
greater, with the critical engine inoperative. That can be a problem for
many light twins, and the payload has to be cut back considerably,
depending on the temperature, of course.

Note, this isn't a certification requirement, it's an operational
requirement, and only IFR.
Click to expand...

Stan,

yes, that makes a lot of sense to me. I can only say that I
wouldn't like to fly VFR either, if I knew that I couldn't climb
on one engine.

This is very theoretical for me, as I have neither an IFR rating
nor a multi-engine rating.

Hans-Georg
 
On 20 Dec 2004 23:36:08 -0000,
If an engine quits right at takeoff in a light twin, shut down
the other one.
But if it quits anywhere else, it gives you a lot more time to
select a place to land, even if you cannot maintain altitude.
Click to expand...

Yes, I'm aware of that. But what I'm saying is that a twin that
cannot climb on one engine is much more risky than one that can.
"Starting with the obvious, large aircraft certified under FAR
Part 25 have certain redundancies and required performance
capabilities that are not required for light aircraft certified
under Part 23 or the old CAR 3, as most of the fleet is. For
example, an engine failure on takeoff in a light piston twin
does not guarantee the pilot any climb performance--none. All it
offers is the opportunity to make a decision. In Part 25
aircraft, which includes some business jets, there is a required
level of performance that gives the pilot something to work
with."

Read it again: "[A]n engine failure on takeoff in a light piston
twin does not guarantee the pilot any climb performance--none."

http://www.aopa.org/asf/asfarticles/sp9710.html
Click to expand...

But this depends only on its loading. You can load a light
piston twin such that it does climb on one engine. And that's
what I would do if I were in that situation.

Hans-Georg
 
Alan Browne said:
"truth" in navigation means a point. There is almost no way that the
average position from GPS over a very, very long period will converge
on that point. The average will wander around near it.
Click to expand...

Logically, of course, the average position can never be a single point.
If all readings showed the same point you wouldn't need to calculate
the average :-)

Juergen Nieveler
 
[email protected] (Iolaos) wrote in
thanks for the precise information.
Click to expand...

The only problem with this "precise information" is that it's
simply WRONG.

"Starting with the obvious, large aircraft certified under FAR
Part 25 have certain redundancies and required performance
capabilities that are not required for light aircraft certified
under Part 23 or the old CAR 3, as most of the fleet is. For
example, an engine failure on takeoff in a light piston twin
does not guarantee the pilot any climb performance--none. All it
offers is the opportunity to make a decision. In Part 25
aircraft, which includes some business jets, there is a required
level of performance that gives the pilot something to work
with."

Read it again: "[A]n engine failure on takeoff in a light piston
twin does not guarantee the pilot any climb performance-- none."

http://www.aopa.org/asf/asfarticles/sp9710.html

Be careful of the information you get on usenet.
Click to expand...

Which is what I said. Part 23 requires that the aircraft demonstrate a
climb with the critical engine inoperative and the gear and flaps
retracted.
Click to expand...

No, it does not.
It does not specify that it has to do that under all
conditions
Click to expand...

In fact, the airplane can be certified under Part 23 even if it
cannot climb SE under ANY conditions.

, nor with the gear down. The manufacturer can demonstrate it
with only a pilot aboard and a few minutes' fuel.
Click to expand...

It doesn't have to demonstrate a climb under those condition,
either.
 
On 20 Dec 2004 23:36:08 -0000,


Yes, I'm aware of that. But what I'm saying is that a twin that
cannot climb on one engine is much more risky than one that
Click to expand...
can.

True.
If that's your consideration, fly a Part 25 certified twin.
But be prepared to pay for it.
"Starting with the obvious, large aircraft certified under FAR
Part 25 have certain redundancies and required performance
capabilities that are not required for light aircraft certified
under Part 23 or the old CAR 3, as most of the fleet is. For
example, an engine failure on takeoff in a light piston twin
does not guarantee the pilot any climb performance--none. All it
offers is the opportunity to make a decision. In Part 25
aircraft, which includes some business jets, there is a required
level of performance that gives the pilot something to work
with."

Read it again: "[A]n engine failure on takeoff in a light piston
twin does not guarantee the pilot any climb performance-- none."

http://www.aopa.org/asf/asfarticles/sp9710.html
Click to expand...

But this depends only on its loading. You can load a light
piston twin such that it does climb on one engine.
Click to expand...

No, you cannot.
There is no requirement in part 23 that requires an aircraft
certified under that part to climb AT ALL on a single engine,
even if the airplane is completely empty.
 
On 22 Dec 2004 03:41:23 -0000,
In fact, the airplane can be certified under Part 23 even if it
cannot climb SE under ANY conditions.
Click to expand...

Problem with such a plane might be that nobody would buy it.

Do any twins exist that cannot climb on one engine at all? I'd
be surprised, except perhaps for some unusual special-purpose
planes.

My thought is that, when the designer of the aircraft reduces
its performance until it can no longer climb on one engine, the
utility value of the plane suddenly drops sharply at that point.
So, if I were designing such planes, I'd hate to do that.

Hans-Georg
 
[email protected] (Iolaos) wrote in
In fact, the airplane can be certified under Part 23 even if it
cannot climb SE under ANY conditions.
Click to expand...

So what do you make of this?
§ 23.67 Climb: One engine inoperative.

(a) For normal, utility, and acrobatic category reciprocating engine-
powered airplanes of 6,000 pounds or less maximum weight, the following
apply:

(1) Except for those airplanes that meet the requirements prescribed in §
23.562(d), each airplane with a VSO of more than 61 knots must be able to
maintain a steady climb gradient of at least 1.5 percent at a pressure
altitude of 5,000 feet with the—

(i) Critical engine inoperative and its propeller in the minimum drag
position;

(ii) Remaining engine(s) at not more than maximum continuous power;

(iii) Landing gear retracted;

(iv) Wing flaps retracted; and

(v) Climb speed not less than 1.2 VS1.

And it goes on with requirements for heavier aircraft......

http://tinyurl.com/4qygz, the cited paragraph at ecfr.gpoaccess.gov, the
Electronic Code of Federal Regulations.
 
[email protected] (Iolaos) wrote in


So what do you make of this?
§ 23.67 Climb: One engine inoperative.
Click to expand...

I should have repeated, as the AOPA article I quoted said, that
"For example, an engine failure on takeoff in a light piston
twin does not guarantee the pilot any climb performance--none."

What I meant is that you cannot reduce the load of many, if not
most, part 23 aircraft enough to guarantee ANY climb performance
*at takeoff*.

Sorry if I was unclear.

Part 25 aircraft are required to be able to make a successful
takeoff at gross takeoff weight if the engine fails at takeoff
safety speed (V1) while still on the ground and maintain a
certain climb gradient.

Part 23 aircraft are not.
 
Mxsmanic said:
David Lesher writes:




I'm not so sure. If Europeans trust each other so much, why aren't they
one country?
Click to expand...

This is not too relevant in this discussion and apparently the decision
was already made. Galileo will come and stay.

Ejo
 

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