Thunderbirds and Altimeters

I've been back channeling for two days now with friends who are
ex-Thunderbirds and professional pilots in other professions. Most of us are
puzzled by the report although not at all puzzled by the results of
Stricklin's mistake!
There's something about this report some of us don't quite get, and it
concerns the zero set on the altimeters. The TB fly a zero set altimeter for
a show. It's not only basic for low altitude acro work, but it's specified
in the regulations for the Thunderbird mission and procedures. (the old
regulation anyway. haven't seen the revised one yet)
My guys however, were on the T38 team, and the TB regulation for practice
might have been changed since then. However, none of us believe that
Stricklin took off with the altimeter set for the elevation at Mountain
Home, which is 2996 feet ASL. That leaves only one scenario; that the
present Viper team must be using a MSL base at Nellis for practice because
of the mountains at Indian Springs. If this is true, then we still can't
figure out why Stricklin would reverse on the roof of his maneuver with a
target altitude of 1600 feet which is basically what happened. It just
doesn't make sense to us. If the team is using a MSL base at Nellis, and
Stricklin was using that base in his mind when he reversed; the elevation at
Nellis is 2000 feet. That would have put his reverse at 4500 feet for the
Viper instead of the 1600 plus he used. 1600 is way low for the Viper even
for a zero set altimeter reference It's very puzzling!!!
Also, there's been a lot of talk about not being able to zero altimeters at
some high elevation airports. This is puzzling also. The Kollsman range,
which is also the basic baro range in the Viper's CADC which drives the
Viper's altimeter in both ELECT and PNEU backup, is aprox 22.00 inches on
the low side and 32.00 inches on the high side. (I had to check this out
with some buddies of mine, as I'd forgotten the range in the Kollsman
myself!! :-)
This gives you, even figuring the 1 inch per thousand rule, an elevation
reset capability to a zero reset before takeoff of 10, 000 feet. This
basically allows a zero reset anywhere in the U.S. at least, allowing for a
standard atmosphere. I don't think I'm missing anything here, but I might
have.....getting older you know!! :-) I just can't remember a zero set being
any problem for me during my tenure as a demonstration pilot.
The Thunderbird's are locked up tighter than a drum right now, and answers
from the present team are not easy to get; so the bottom line so far for us
old timers trying to figure this out is that the team indeed does use a MSL
reference at Nellis because of the mountains, but resets to a zero altimeter
set before takeoff at the show site. If this is the case, it's
understandable to me how Chris Stricklin could have made the mistake he did.
I'll tell you up front. I can sympathize with Chris Stricklin, or anyone
else for that matter who has to work low altitude acro this way. If there's
one thing that will kill you doing low work it's non-standardization. If the
Birds have to use a MSL calculation for their roof target altitudes at
Nellis for a vertical plane maneuver because of the mountains, then revert
to a zero set when doing a show; that in my opinion is bad news! It's only a
matter of time when things like this catch up to you when doing low work in
high performance airplanes.
Chris Stricklin is a damn good pilot. He's also a damn lucky pilot!
What happened to Stricklin has happened to a lot of very good pilots who do
low work. If all this reporting is true, he was simply bitten by non
standardization! I understand the situation's being looked at closely by the
Air Force. That's one good thing anyway, although I don't see how they're
going to change anything unless they can take the mountains at Nellis out of
the Thunderbird equation.
Frankly, the whole damn thing is puzzling to us; us being myself and a few
ex-Thunderbirds. I know I'll probably pick up the straight scoop sooner or
later through my grapevine, but for right now, this report, and putting it
together for a clear picture of what happened to Stricklin is one large
puzzle in progress.
Dudley Henriques
International Fighter Pilots Fellowship
Commercial Pilot/ CFI Retired
For personal email, please replace
the z's with e's.
dhenriquesATzarthlinkDOTnzt

"Dudley Henriques" wrote...

The Kollsman range,
which is also the basic baro range in the Viper's CADC which drives the
Viper's altimeter in both ELECT and PNEU backup, is aprox 22.00 inches on
the low side and 32.00 inches on the high side.

This gives you, even figuring the 1 inch per thousand rule, an elevation
reset capability to a zero reset before takeoff of 10, 000 feet. This
basically allows a zero reset anywhere in the U.S. at least, allowing for a
standard atmosphere.

Not quite...

You have a 10,000' nominal range using that rule of thumb, but from the 29.92"
standard you only have 7,920' of 'low' correction available at sea level, and
2080' of 'high' correction. That gives you QFE capability up to an airport
elevation of 7,920'. Still, as you say, adequate for most US airports in most
conditions.

It also illustrates the complexity in attempting to fly IFR using QFE (0' runway
altitude) at high-altitude airports. If you use the wrong setting, misinterpret
a controller's QFE / QNH call, or use the wrong minimums on a chart, it can be
deadly. Those errors are all too easy to make, especially if you are not used
to using QFE at all.

"Dudley Henriques" wrote:

[snipped for brevity]

There's something about this report some of us don't quite get, and it
concerns the zero set on the altimeters. The TB fly a zero set altimeter for
a show. It's not only basic for low altitude acro work, but it's specified
in the regulations for the Thunderbird mission and procedures

What puzzles me isn't whether or not he zeroed the altimeter prior to
launch or was attempting to convert AGL elevations to MSL altitudes,
but rather why he failed to recognize via outside visual cues that he
was simply too low to the ground to even THINK about initiating a
Split-S maneuver.

Clearly, he knew that something was wrong early on since he reportedly
exerted "maximum back stick pressure and rolled slightly left to
ensure the aircraft would impact away from the crowd should he
have to eject." Despite his exceedingly close proximity to the ground
the fact that he managed to eject successfully is another indication
that he realized quite early on that he done screwed up!

If you look at the cockpit video it's obvious that his head is tilted
way back watching the horizon while he was inverted prior to initating
the Split-S. My primary question is why he didn't abort the Split-S
and simply continue the roll at the top of the maneuver and perform
an Immelmann instead of pressing on with the Split-S?

"Mike Marron" wrote in message
...
"Dudley Henriques" wrote:

[snipped for brevity]

There's something about this report some of us don't quite get, and it
concerns the zero set on the altimeters. The TB fly a zero set altimeter
for
a show. It's not only basic for low altitude acro work, but it's
specified
in the regulations for the Thunderbird mission and procedures

What puzzles me isn't whether or not he zeroed the altimeter prior to
launch or was attempting to convert AGL elevations to MSL altitudes,
but rather why he failed to recognize via outside visual cues that he
was simply too low to the ground to even THINK about initiating a
Split-S maneuver.

Clearly, he knew that something was wrong early on since he reportedly
exerted "maximum back stick pressure and rolled slightly left to
ensure the aircraft would impact away from the crowd should he
have to eject." Despite his exceedingly close proximity to the ground
the fact that he managed to eject successfully is another indication
that he realized quite early on that he done screwed up!

If you look at the cockpit video it's obvious that his head is tilted
way back watching the horizon while he was inverted prior to initating
the Split-S. My primary question is why he didn't abort the Split-S
and simply continue the roll at the top of the maneuver and perform
an Immelmann instead of pressing on with the Split-S?

This is our observation exactly! Pilots who survive low altitude demo work
are NOT one cue pilots, but respond to multiple cues, many peripheral. All
of us discussing this back channel are in complete agreement with your
observation about visual cues.
The g line required to put the Viper in reverse at 1600 was higher than that
which would have been normal. This should have been a physical cue. The
horizon is different at 1600 than at 2500. This is a visual cue.
The inverted ground area showing past the canopy bow edge is wider (more
detailed ground area meets the eye) at 1600 than at 2500. This is a
peripheral visual cue.
The inverted pull is escapable in roll until just before exact vertical. The
shortest way out using roll must allow for snatch factor and roll rate and
this occurs in an airplane with the Viper's roll capability in this maneuver
profile at just before 90 degrees nose down. From then on it's a straight
pull commit. The Viper can be flown into a pitch rate defeat on the limiter
and that's where he put it apparently. I make it a dead airplane from 90
degrees nose down in the pull and a dead pilot except for the seat
capability.
The altimeter reference however, remains a puzzle for us.
Dudley

"John R Weiss" wrote in message
news:eHbRb.152481$I06.1538887@attbi_s01...
"Dudley Henriques" wrote...

The Kollsman range,
which is also the basic baro range in the Viper's CADC which drives the
Viper's altimeter in both ELECT and PNEU backup, is aprox 22.00 inches
on
the low side and 32.00 inches on the high side.

This gives you, even figuring the 1 inch per thousand rule, an elevation
reset capability to a zero reset before takeoff of 10, 000 feet. This
basically allows a zero reset anywhere in the U.S. at least, allowing
for a
standard atmosphere.

Not quite...

You have a 10,000' nominal range using that rule of thumb, but from the
29.92"
standard you only have 7,920' of 'low' correction available at sea level,
and
2080' of 'high' correction. That gives you QFE capability up to an
airport
elevation of 7,920'. Still, as you say, adequate for most US airports in
most
conditions.

Yeah, that's right JW. There's a positive/negative factor in there above
that 29.92 that splits that 10K.

It also illustrates the complexity in attempting to fly IFR using QFE (0'
runway
altitude) at high-altitude airports. If you use the wrong setting,
misinterpret
a controller's QFE / QNH call, or use the wrong minimums on a chart, it
can be
deadly. Those errors are all too easy to make, especially if you are not
used
to using QFE at all.

This really points out why a zero setting should ONLY be used for aerobatic
work, and even then, only for LOCAL aerobatic work!!
Dudley

"Dudley Henriques" wrote in message
link.net...

"John R Weiss" wrote in message
news:eHbRb.152481$I06.1538887@attbi_s01...
"Dudley Henriques" wrote...

Yeah, that's right JW. There's a positive/negative factor in there above
that 29.92 that splits that 10K.

That should be above AND below 29.92!!! :-)
D

What I don't understand, is why he didn't realize he was too low when
he rolled over and looked down? Seems like if he's done this for awhile
he would get a sense of good and bad? But maybe being on the road
and all the different locations they fly makes this a poor judgment tool.

Watching the cockpit video, the ground sure looks close to me, as the
B-52's on the ramp are filling the window :-)

"Dudley Henriques" wrote

I've been back channeling for two days now with friends who are
ex-Thunderbirds and professional pilots in other professions.

"Mike Marron" wrote

My primary question is why he didn't abort the Split-S
and simply continue the roll at the top of the maneuver and perform
an Immelmann instead of pressing on with the Split-S?

He would have had to buy the first round at the club for missing the
maneuver, and everyone would have bought him a round if he somehow
pulled it out of his ***. Ah well, no one went to the club that day...

It looks like a simple mistake really. What it amounts to is that he
mentally used the reference altitude the team uses at Nellis which put him
800 feet low on the roof. This kind of lapse can happen; just not in the low
altitude aerobatic business! The physical and visual cues missed I have no
answer for. You either see them or you don't. You don't have time to
mentally calculate. Your mind, eyes, and body either pick up on these things
or they don't. Somehow, he missed the cues. They were there. I know they
were there because I've seen and felt them myself many times doing exactly
what he was doing. It's almost impossible to explain to people who haven't
actually flown low altitude demonstration work. Anyway, he made it. He won't
get a chance to try it again, but it looks like the AF has learned enough
from this to make a few corrections that might help the next guy down the
road!
Dudley Henriques
International Fighter Pilots Fellowship
Commercial Pilot/ CFI Retired
For personal email, please replace
the z's with e's.
dhenriquesATzarthlinkDOTnzt
"S. Sampson" wrote in message
news:dphRb.1296$Q_4.438@okepread03...
What I don't understand, is why he didn't realize he was too low when
he rolled over and looked down? Seems like if he's done this for awhile
he would get a sense of good and bad? But maybe being on the road
and all the different locations they fly makes this a poor judgment tool.

Watching the cockpit video, the ground sure looks close to me, as the
B-52's on the ramp are filling the window :-)

"Dudley Henriques" wrote

I've been back channeling for two days now with friends who are
ex-Thunderbirds and professional pilots in other professions.

Without pre-judging this pilot, what happens to a pilot who makes a mistake
and totals the aircraft? Out of the team? or out of the AF completely?

Nick