Interial Nav Systems

[Duck Dog]

I was reading some of the ICAO findings of the Korean Air 007
shootdown, and I was struck by the fact that an intertial navigation
system on the 747 was used for much of the overseas flight. Of
course, this was 1983 and GPS was probably not used in civilian
aircraft yet, so I really shouldn't be surprised. Does anyone know if
INS is still used on civilian airliners, particularly on overseas
flights?

[John Gaquin]

"Duck Dog" > wrote in message

> ...Does anyone know if
> INS is still used on civilian airliners, particularly on overseas
> flights?


Trans-oceanic or polar flights are about the only place you'd need one,
anyway. When I last flew (mid-90s) my employer, a non-sked freight hauler,
was looking into converting from INS to GPS. I'm guessing there aren't many
INSs left, at least on US registered craft.

JG

[Earl]

> > ...Does anyone know if
> > INS is still used on civilian airliners, particularly on overseas
> > flights?
>
>
> Trans-oceanic or polar flights are about the only place you'd need one,
> anyway. When I last flew (mid-90s) my employer, a non-sked freight
hauler,
> was looking into converting from INS to GPS. I'm guessing there aren't
many
> INSs left, at least on US registered craft.
>

I got a cockpit tour of a United 767-300ER in year 2000 that was used for
overseas international flights. Crew said they have 3 INS units on board.

[Robert Moore]

(Duck Dog) wrote

> I was reading some of the ICAO findings of the Korean Air 007
> shootdown, and I was struck by the fact that an intertial
> navigation system on the 747 was used for much of the overseas
> flight. Of course, this was 1983 and GPS was probably not used
> in civilian aircraft yet, so I really shouldn't be surprised.
> Does anyone know if INS is still used on civilian airliners,
> particularly on overseas flights?

What would you have used??? :-) When I first started flying,
we were still using the Nantucket CONSOLAN for oceanic flying.

During the B-707 and DC-8 days, INS was a very expensive method
of navigation. In addition to the initial cost, the routine
maintenance on the gyros was very costly. American Airlines
actually prohibited the use of the INS on domestic flight legs.
With the introduction of the B-747, the gyros were put to a dual
use, INS and AHRS (attitude heading reference system) and with
the introduction of the ring-laser gyro, maintenance cost have
gone way down.
Boeing's latest jetliners are still equipped with a ring-laser
gyro based IRS (inerial reference system). Since INS is a DR
(dead reckoning) system, some method must be provided to update
and correct the IRS position. Previously, this was accomplished
with VOR/DME and now, GPS has been added to the mix.
BTW, the full constellation of 24 GPS satellites was not achieved
until 1994.
Flight crew failure was the cause of the KA 007 incident, not a
problem with the INS.

Bob Moore
PanAm (retired)

[John Gaquin]

"Earl" > wrote in message news:1EOub.4834> >
>
> I got a cockpit tour of a United 767-300ER in year 2000 that was used for
> overseas international flights. Crew said they have 3 INS units on board.
>
>

Well, there ya go!

[BTIZ]

it would not have mattered.. the navigational way point was loaded wrong..
there was nothing wrong (ASAIK) with the inertial nav system, it was going
where the pilot programmed.

BT

"Duck Dog" > wrote in message
om...
> I was reading some of the ICAO findings of the Korean Air 007
> shootdown, and I was struck by the fact that an intertial navigation
> system on the 747 was used for much of the overseas flight. Of
> course, this was 1983 and GPS was probably not used in civilian
> aircraft yet, so I really shouldn't be surprised. Does anyone know if
> INS is still used on civilian airliners, particularly on overseas
> flights?

[Gerald Sylvester]

> I got a cockpit tour of a United 767-300ER in year 2000 that was used for
> overseas international flights. Crew said they have 3 INS units on board.

my friend just got bumped down off the 767 with UA. I remember him
saying it had 3 INS units. He used to fly the 777 and said, "we
weren't even told how many INS it has" apparently due to the systems
on the 777 having so many redundencies (this is from memory). I think
he also said that the 777 has 9 hydraulic systems. If 8 of them
fail, the remaining system can power the other 8.

Gerald

[Duck Dog]

Robert Moore > wrote in message >...
> (Duck Dog) wrote
>
> > I was reading some of the ICAO findings of the Korean Air 007
> > shootdown, and I was struck by the fact that an intertial
^^^^^^^^^
Well, no one caught my spelling error, so I guess I'll just flame
myself ;-)


> > navigation system on the 747 was used for much of the overseas
> > flight. Of course, this was 1983 and GPS was probably not used
> > in civilian aircraft yet, so I really shouldn't be surprised.
> > Does anyone know if INS is still used on civilian airliners,
> > particularly on overseas flights?
>
> What would you have used??? :-)

Rand McNally? ;-)

> When I first started flying,
> we were still using the Nantucket CONSOLAN for oceanic flying.
>
> During the B-707 and DC-8 days, INS was a very expensive method
> of navigation. In addition to the initial cost, the routine
> maintenance on the gyros was very costly. American Airlines
> actually prohibited the use of the INS on domestic flight legs.
> With the introduction of the B-747, the gyros were put to a dual
> use, INS and AHRS (attitude heading reference system) and with
> the introduction of the ring-laser gyro, maintenance cost have
> gone way down.
> Boeing's latest jetliners are still equipped with a ring-laser
> gyro based IRS (inerial reference system). Since INS is a DR
> (dead reckoning) system, some method must be provided to update
> and correct the IRS position. Previously, this was accomplished
> with VOR/DME and now, GPS has been added to the mix.

As an aside, my understanding of military aircraft, particularly
combat aircraft, is that they rely much more on INS than GPS. I'm
just guessing, but I'd bet that stems from the assumption that in
full-scale conflict the GPS constellation will be unavailable for
whatever reason, and that INS (which doesn't rely on external
navigation facilities) can continue to provide very accurate
positioning data.

> BTW, the full constellation of 24 GPS satellites was not achieved
> until 1994.

OK, but I remember that GPS was highly touted in the first Gulf War,
so it's been operational for at least a while longer than that.

> Flight crew failure was the cause of the KA 007 incident, not a
> problem with the INS.

I understand that. I was just struck by the references to INS. BTW,
do you know whether any INS systems are used in GA aircraft?

> Bob Moore
> PanAm (retired)

[Dean Wilkinson]

The 777 INS has two reference systems. They are the ADIRU and SAARU.
The ADIRU is the Air Data Inertial Reference Unit and the SAARU is the
Standby Airdata Attitude Reference Unit. The ADIRU utilized laser
ring gyros and accelerometers while the SAARU uses lower cost fiber
optic ring gyros and accelerometers.

The ADIRU is a fault-tolerant design, so there is internal redundancy
within the system itself. The SAARU acts as a safety backup for the
ADIRU in case something takes out the entire ADIRU defeating its
fault-tolerant design.

The FMS (Flight Management System) function within AIMS (Airplane
Information Management System) utilizes data from the ADIRU and SAARU
as well as from navigation radio sources including GPS, DME, VOR, and
NDB to update the intertial navigation solution to maintain an
accurate position fix.

Dean Wilkinson

Gerald Sylvester > wrote in message et>...
> > I got a cockpit tour of a United 767-300ER in year 2000 that was used for
> > overseas international flights. Crew said they have 3 INS units on board.
>
> my friend just got bumped down off the 767 with UA. I remember him
> saying it had 3 INS units. He used to fly the 777 and said, "we
> weren't even told how many INS it has" apparently due to the systems
> on the 777 having so many redundencies (this is from memory). I think
> he also said that the 777 has 9 hydraulic systems. If 8 of them
> fail, the remaining system can power the other 8.
>
> Gerald

[[email protected]]

On 20 Nov 2003 05:56:42 -0800, (Duck Dog) wrote:

snip

>I understand that. I was just struck by the references to INS. BTW,
>do you know whether any INS systems are used in GA aircraft?

snip

Not sure about the GA question.

I maintain a 1988 Hawker 800A that has one Laseref INS system. It also
has two independent GPS systems (added in the last 5 years).

Know of a couple local Gulfstreams (kinda getting out of the GA thing)
a III and a IV that have at least two independent INS systems. Am
thinking that the IV has three, but am not positive.

TC

[David CL Francis]

On Wed, 19 Nov 2003 at 14:21:04 in message
>, John Gaquin
> wrote:
>
>"Earl" > wrote in message news:1EOub.4834> >
>>
>> I got a cockpit tour of a United 767-300ER in year 2000 that was used for
>> overseas international flights. Crew said they have 3 INS units on board.
>>
>>
In 2001 I had a ride into Kennedy in a 747-400. I asked about GPS when
we were waiting on the ground (we could not get to our designated gate).
The Captain brought up the Position reference Page on the FMC and showed
me that the three lines for the INS and the FMC position line display,
now had a fourth, the GPS position added.
--
David CL Francis