How long does an IRS take to align?
This is really addressed specifically at operators of the Boeing 737-400, but I can't imagine that the B747, 757/767, or 777 are very different. Airbus might be.
There is a JAA exam question which asks how long the B737-400 IRS takes to align. I take this to mean from the moment you select ALIGN or NAV.
The candidate is asked to choose from between 9 minutes and 12 minutes.
Now, my view is that it will depend on the latitude because, the higher the latitude, the less Earth Rate there is to detect. However, I would expect that, at ther same latitude, the time taken to align for a particular system would be very consistent day to day.
My question, to all you Boeing operators, is - At temperate latitudes, is it nearer 9 or 12 minutes? I can't find any references.
Any help from the sharp end gratefully received.