Scared of mid-airs

On Tue, 1 Aug 2006 07:18:09 -0600, "Jeff Crowell"
wrote in :

[...]
You have been claiming that the speed of the USAF flight
was "480 knots (550 mph) at impact" (your post, 7/14),
when actual recorded speed at impact was 356 KCAS
per the accident report.

[That would be Message-ID:
]


AIB Report mentions the 480 knot closure speed twice:

AIB Report:

"The closure rate of Cessna 829 and Ninja 1 based on
radar-measured conflict alert data just prior to the collision was
approximately 480 KTAS."

"Based on their closure rate of approximately 480 knots," ...

With regard to your 356 KCAS airspeed at the time of impact, that is
not given as Ninja 2's speed in the AIB nor NTSB reports. Here's the
only reference to that number I was able to find in either document:

AIB Report:

"Ninja 1’s displayed airspeed at the time of the midair was
356 KCAS" ...

You'll recall that Ninja 1 was not the aircraft that impacted the
Cessna. (I find the fact that the AIB report equates 'displayed
airspeed' with calibrated air speed a bit puzzling. Do F-16 airspeed
indicators actually display calibrated airspeed?)

So, lacking evidence to the contrary, I used the closing speed as the
speed at the time of impact. That may be incorrect, but lacking
better information, it seems reasonable to me, and not an exaggeration
nor hyperbole.

[...]

The USAF Accident Investigation Board's report:

"Ninja flight's mistake was in transitioning to the tactical
portion of their flight too early, unaware that they were in
controlled airspace."

That was President, Accident Investigation Board Robin E. Scott's
opinion. It is not fact.

Despite the fact that Parker failed to brief terminal airspace prior
to the flight as regulations require, I personally find it difficult,
if not impossible, to believe Parker was unaware, that the 60 mile
diameter Tampa Class B terminal airspace lay below him at the time he
chose to descend below 10,000' into it.

That's opinion, too, annit?

I suppose it is my reasoned opinion.

If you disagree, perhaps you could explain how Parker could have been
unaware of a chunk of terminal airspace 60 miles in diameter and
10,000' feet high on a clear day; I can't. He surely must have been
able to see the large international airport beneath him. Every pilot
knows there is controlled terminal airspace around such airports.
Additionally, Parker was attempting to contact ATC to obtain a
clearance to enter the Class B airspace immediately before he chose to
descend with out the required ATC clearance. Given those facts, how
could Parker possibly have been unaware of what he was doing? Lacking
an answer to that question, in light of the circumstances, logic and
reason demand, that I conclude, that Parker deliberately chose to
violate regulations prohibiting his descent into congested terminal
airspace without the required ATC clearance.


Per the F-16 Dash 1 he was allowed to be at 350 knots at
that altitude, and was traveling only slightly faster at the time
of the collision. What about that statement (from the
accident investigation) do you not understand?

Jeff, I understand that 450 knots within congested terminal airspace
is about one third faster than the 350 knot speed limit you state
above. One third is not 'slightly faster'. It is _significantly_
faster. (The 450 knot figure is quoted from the AIB report at the
beginning of this follow up article.) Perhaps you can provide the
reasoning you used in arriving at your conclusion.

Speed of the F-16 at impact was 356 KCAS.

Limiting the discussion to your 356 KCAS speed at the time of impact
figure disregards this fact:

Final NTSB Report MIA01FA028A:


http://www.ntsb.gov/NTSB/brief2.asp?...A028A &akey=1
"Speeds of up to 450 knots were noted during the descent."

Why would you overlook that 450 knot speed? Does the F-16 Dash 1 only
pertain to the speed at time of impact? :-)

Jeff Crowell wrote:
You have been claiming that the speed of the USAF flight
was "480 knots (550 mph) at impact" (your post, 7/14),
when actual recorded speed at impact was 356 KCAS
per the accident report.

Larry Dighera wrote:
[That would be Message-ID:
]

AIB Report mentions the 480 knot closure speed twice:
AIB Report:
"The closure rate of Cessna 829 and Ninja 1 based on
radar-measured conflict alert data just prior to the collision was
approximately 480 KTAS."

"Based on their closure rate of approximately 480 knots," ...

With regard to your 356 KCAS airspeed at the time of impact, that is
not given as Ninja 2's speed in the AIB nor NTSB reports. Here's the
only reference to that number I was able to find in either document:

AIB Report:

"Ninja 1's displayed airspeed at the time of the midair was
356 KCAS" ...

You'll recall that Ninja 1 was not the aircraft that impacted the
Cessna. (I find the fact that the AIB report equates 'displayed
airspeed' with calibrated air speed a bit puzzling. Do F-16 airspeed
indicators actually display calibrated airspeed?)

I certainly grant the difference between Ninjas 1 and 2.
Don't you think that if Ninja 2 was flying form on Ninja 1,
their speeds must have been pretty close? And, I say again,
blithely using closure speed as speed of the mishap aircraft is
purposely deceptive.

As for KCAS versus KIAS in displays, I have no time in
F-16s, so I can't answer that categorically. But since
KCAS corrects for system error, it is more accurate than
KIAS, so why not? It would not surprise me if what's
displayed on the HUD, for example, and therefore
recorded by the tapes, is KCAS, since data displayed
there has been massaged by the aircraft's air data
computer (or some analogous system)...


So, lacking evidence to the contrary, I used the closing speed as the
speed at the time of impact. That may be incorrect, but lacking
better information, it seems reasonable to me, and not an exaggeration
nor hyperbole.

It doesn't strike you as even a little bit inflammatory in light
of your usage of that number? What the hey, you're only
off by 25%. Close enough, huh?


Per the F-16 Dash 1 he was allowed to be at 350 knots at
that altitude, and was traveling only slightly faster at the time
of the collision. What about that statement (from the
accident investigation) do you not understand?

Jeff, I understand that 450 knots within congested terminal airspace
is about one third faster than the 350 knot speed limit you state
above. One third is not 'slightly faster'. It is _significantly_
faster. (The 450 knot figure is quoted from the AIB report at the
beginning of this follow up article.) Perhaps you can provide the
reasoning you used in arriving at your conclusion.

Speed of the F-16 at impact was 356 KCAS.

Limiting the discussion to your 356 KCAS speed at the time of impact
figure disregards this fact:

Final NTSB Report MIA01FA028A:

http://www.ntsb.gov/NTSB/brief2.asp?...A028A &akey=1
"Speeds of up to 450 knots were noted during the descent."

Why would you overlook that 450 knot speed? Does the F-16 Dash 1 only
pertain to the speed at time of impact? :-)

Somewhere during the entire flight, Ninja 2's speed might
easily have been supersonic; would that have had any influence
on the collision? (other than the cosmic scheduling of it all--
obviously, anything which might have occurred to either F-16
or Cessna to speed or delay their movements throughout their
respective flights that day would have prevented this tragedy).
Seen that way, if Ninja had gone even a little faster then this
would have been nothing more than a close miss.

I never debated that Ninja flight recorded a speed of 450
knots during the flight. I'm simply saying that the speed
that really matters is the speed immediately prior to the
collision. I have not seen any claim other than yours that
Ninja was knocking down 450 knots within that critical
interval. And you are clearly selecting your data to put
your argument in the best possible light.

Similarly, the fact that closure rate was 480 knots of
course has meaning in terms of how much time was
available to both pilots to see and avoid. But to imply or
suggest that this is in any way the same as saying
that Ninja was making almost 500 knots at impact is a
blatant lie.


Jeff

On Thu, 3 Aug 2006 06:54:23 -0600, "Jeff Crowell"
wrote:

As for KCAS versus KIAS in displays, I have no time in
F-16s, so I can't answer that categorically. But since
KCAS corrects for system error, it is more accurate than
KIAS, so why not? It would not surprise me if what's
displayed on the HUD, for example, and therefore
recorded by the tapes, is KCAS, since data displayed
there has been massaged by the aircraft's air data
computer (or some analogous system)...

Just a refresher for those who have been out of pilot training for a
long time:

ICE-T is the mnemonic for remembering the calculations involving going
from airspeed on the pitot-static gauge (Where's Tarver these days?)
to real, honest-to-God speed through the air.

Indicated airspeed is the uncorrected number of the pitot instrument.

Calibrated AS is corrected for "position error"--in the early days
pitot tubes often were placed conveniently for designers but that
resulted in either boundary layer distortions or plumbing errors along
the tubing to the diaphragm of the gauge. Modern aircraft (since the
'50s) minimize this error and for all practical considerations
Indicated is equal to Calibrated. As Jeff states, data processing
through the air data computer makes this computation.

Equivalent airspeed correct calibrated for "compressibility
error"--the fact that air is an elastic substance and at transonic
speeds creates molecule buildup at the pitot tube that distorts the
reading of the gauge. Typically Equivalent will be slightly lower than
Calibrated. At trans-sonic speeds the error spikes in a narrow regime
but then returns to small error less than Calibrated.

True airspeed is Equivalent airspeed corrected for air density.
Temperature and pressure reduce air density meaning fewer molecules
per cubic unit of atmosphere to register on the pneumatic instrument.
So, an indication is always lower than actual speed through the air.
Rule of thumb for standard day is 2% per thousand feet of altitude.
So, true airspeed is always higher than indicated and at high
altitudes is considerably higher.

This technical data should leave Larry calculating and seeking
further charts and documentation for weeks. When he returns I am sure
the speed of convergence will not be translated into TAS so that the
differentials are the maximum.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

On Thu, 3 Aug 2006 06:54:23 -0600, "Jeff Crowell"
wrote in :

[...]

Speed of the F-16 at impact was 356 KCAS.

Limiting the discussion to your 356 KCAS speed at the time of impact
figure disregards this fact:

Final NTSB Report MIA01FA028A:

http://www.ntsb.gov/NTSB/brief2.asp?...A028A &akey=1
"Speeds of up to 450 knots were noted during the descent."

Why would you overlook that 450 knot speed? Does the F-16 Dash 1 only
pertain to the speed at time of impact? :-)

Somewhere during the entire flight, Ninja 2's speed might
easily have been supersonic;

Perhaps. But any speed in excess of the minimum safe speed is a
violation of regulations below 10,000'.

would that have had any influence
on the collision? (other than the cosmic scheduling of it all--
obviously, anything which might have occurred to either F-16
or Cessna to speed or delay their movements throughout their
respective flights that day would have prevented this tragedy).
Seen that way, if Ninja had gone even a little faster then this
would have been nothing more than a close miss.

That analysis disregards the fact that there were other aircraft
present in the congested Class B and C terminal airspace that could
have been impacted just as easily by the Ninja flight.

I never debated that Ninja flight recorded a speed of 450
knots during the flight. I'm simply saying that the speed
that really matters is the speed immediately prior to the
collision.

That conclusion is debatable. If we're discussing time to deconflict,
we'd need to know at what point the Ninja flight achieved 450 knots.

I have not seen any claim other than yours that
Ninja was knocking down 450 knots within that critical
interval. And you are clearly selecting your data to put
your argument in the best possible light.

Perhaps. At any rate, I commend you for taking the time to analyze
all the data available. That has to be an enlightening experience.

And I'm reassured that by the limited discrepancies you have provided,
the vast majority of what I have said is correct.

Similarly, the fact that closure rate was 480 knots of
course has meaning in terms of how much time was
available to both pilots to see and avoid. But to imply or
suggest that this is in any way the same as saying
that Ninja was making almost 500 knots at impact is a
blatant lie.


That conclusion is dependent on malice of intent, which I feel is
unwarranted, and unsupported by the facts. We just choose to
interpret the facts differently.

Jeff Crowell wrote:
Speed of the F-16 at impact was 356 KCAS.

Larry Dighera wrote:
Limiting the discussion to your 356 KCAS speed at the time of impact
figure disregards this fact:
http://www.ntsb.gov/NTSB/brief2.asp?...A028A &akey=1
"Speeds of up to 450 knots were noted during the descent."

Why would you overlook that 450 knot speed? Does the F-16 Dash 1 only
pertain to the speed at time of impact? :-)

Jeff Crowell:
Somewhere during the entire flight, Ninja 2's speed might
easily have been supersonic;

Larry Dighera:
Perhaps. But any speed in excess of the minimum safe speed is a
violation of regulations below 10,000'.

Of course. But hardly a smoking gun.


would that have had any influence
on the collision? (other than the cosmic scheduling of it all--
obviously, anything which might have occurred to either F-16
or Cessna to speed or delay their movements throughout their
respective flights that day would have prevented this tragedy).
Seen that way, if Ninja had gone even a little faster then this
would have been nothing more than a close miss.

That analysis disregards the fact that there were other aircraft
present in the congested Class B and C terminal airspace that could
have been impacted just as easily by the Ninja flight.

But they were not, were they?


I never debated that Ninja flight recorded a speed of 450
knots during the flight. I'm simply saying that the speed
that really matters is the speed immediately prior to the
collision.

That conclusion is debatable. If we're discussing time to deconflict,
we'd need to know at what point the Ninja flight achieved 450 knots.

For starters, if the accident investigation report does not
specifically say that the 450 knot speed phases of the
flight were not a proximate cause of the mishap, we can
be sure it was not.


I have not seen any claim other than yours that
Ninja was knocking down 450 knots within that critical
interval. And you are clearly selecting your data to put
your argument in the best possible light.

Perhaps. At any rate, I commend you for taking the time to analyze
all the data available. That has to be an enlightening experience.

Excuse me? Care to say what you mean here?


And I'm reassured that by the limited discrepancies you have provided,
the vast majority of what I have said is correct.

That would be just one more example of you making a
conclusion that is not supported by facts. I have been
attempting to limit our discussion to a limited set of data
so that it is easier to keep up.


Similarly, the fact that closure rate was 480 knots of
course has meaning in terms of how much time was
available to both pilots to see and avoid. But to imply or
suggest that this is in any way the same as saying
that Ninja was making almost 500 knots at impact is a
blatant lie.

That conclusion is dependent on malice of intent, which I feel is
unwarranted, and unsupported by the facts. We just choose to
interpret the facts differently.

"Malice of intent"?

You are convinced, in the face of data to the contrary
(and with no data in support), that the mishap pilot got
up with the specific intention of killing a civil air pilot
that day.

You cast away entire chunks of data from the mishap
investigation report just because they do not fit with
your preconceived notion.


Jeff