IRS drift - Details please ?
Joined: Apr 2010
Posts: 7,056
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From: London
As Underfire and Asquared point out there are a number of errors or rather inaccuracies that lead to "drift"
You'd imagine that some of them would/should cancel each other out but it never seems to work that way - they always tend to be additative....................
You'd imagine that some of them would/should cancel each other out but it never seems to work that way - they always tend to be additative....................
Joined: Jan 2011
Posts: 780
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From: Seattle
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Joined: Apr 2009
Posts: 3,336
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From: On the Beach
As Underfire and Asquared point out there are a number of errors or rather inaccuracies that lead to "drift"
You'd imagine that some of them would/should cancel each other out but it never seems to work that way - they always tend to be additative....................
You'd imagine that some of them would/should cancel each other out but it never seems to work that way - they always tend to be additative....................
The modern stuff keeps the IRS accurate by continuing tweaking the position with the GPS inputs. If all airframes that are RNP AR qualified had these types of IRU/IRS, the containment assumptions for RNP missed approaches could be significantly less than those used in today's criteria. The RNP missed approach assumes loss of GPS and IRU/IRS drift rates of the older units.
Joined: Jun 2001
Aviation Qualifications: ATPL
Posts: 1,187
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From: OZ
Pepperseed, INS DME updating was available provided you had a valid signal from the DME.
EEngr That was the reason for the carouseling, to randomise errors by turning the INU platform at, as I recall it, 4 RPM. It was pretty good with residual errors rarely anywhere even close to the 3+3T limit.
EEngr That was the reason for the carouseling, to randomise errors by turning the INU platform at, as I recall it, 4 RPM. It was pretty good with residual errors rarely anywhere even close to the 3+3T limit.
