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A320 IRS Drift Over Time

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A320 IRS Drift Over Time

Old 27th Apr 2023, 11:48
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A320 IRS Drift Over Time

I am planning on doing an 'Around the world' flight in a Study level A319 Simulator. (which does simulate IRS drift)

I was planning on keeping the IRS's on after each landing to save on time and effort to align them each time, but I am worried about drift adding over time.
I assume most LCC's today probably don't realign the IRS's after each flight, till they secure the plane after the last flight of the day.

Practically, would it be a concern?
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Old 27th Apr 2023, 15:26
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If itís genuinely modelling the IRS as fitted to the aircraft then just do a fast align.
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Old 28th Apr 2023, 00:05
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You'll also have plenty of time to do a full alignment if it simulates the actual fuel uplift rate.

Policies at airlines will vary, but it's unlikely a narrowbody will go a whole day on just one alignment.
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Old 28th Apr 2023, 00:14
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Originally Posted by Zar_1
I am planning on doing an 'Around the world' flight in a Study level A319 Simulator. (which does simulate IRS drift)

I was planning on keeping the IRS's on after each landing to save on time and effort to align them each time, but I am worried about drift adding over time.
I assume most LCC's today probably don't realign the IRS's after each flight, till they secure the plane after the last flight of the day.

Practically, would it be a concern?
IRS alignment time is in the order of minutes.
Refuelling and preflight will take longer. Youíre not saving any time by skipping it.
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Old 28th Apr 2023, 13:43
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Ok guys, thanks a lot for the replies... certainly very grateful for your time

Any other considerations/tips for this particular adventure?
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Old 28th Apr 2023, 18:01
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If we fly through an area known to be subject ti GPS interference (Cyprus, Eastern Turkey, etc) then it's common sense to perform a full alignment.

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Old 29th Apr 2023, 14:45
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Originally Posted by Zar_1
I am planning on doing an 'Around the world' flight in a Study level A319 Simulator. (which does simulate IRS drift)

I was planning on keeping the IRS's on after each landing to save on time and effort to align them each time, but I am worried about drift adding over time.
I assume most LCC's today probably don't realign the IRS's after each flight, till they secure the plane after the last flight of the day.

Practically, would it be a concern?
Hi,

from a procedural point of view you would perform a complete IRS alignment if it was:

- First flight of the day or
- Crew change or
- Departure airport located between 2į North and South or
- GPS not available and poor NAVAID coverage enroute or
- GPS not available and flight time greater than 3 hours.

Other than that you would perform a fast alignment if the difference between the IRS position and FMGC position is at or above 5 NM.

Bottom line if You want some proper level of realism just do a full alignment every time you fire up your Sim.
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