NATS position plotting???

[Seagul1]

Was wondering if anyone could highlight their procedures about position plotting on the NATS routes.Since the IRS position is used to plot the position (without GPS that is) if the IRS has drifted how would you know that you are of track until you are inrange of a ground based nav aid since the coordinates shown by the IRS would be the same as the CFP? This would be the IRS that is being used for the navigation.

[kijangnim]

Greetings
Are you FMC equipped?

[Seagul1]

Can you please explain in both cases...i.e. with and without FMC many thanks

[Sunshine Express]

2 or three IRS, so you should be aware if one has wandered off.

Each one also gives a probability of accuracy.

GPS....sorted

[FullWings]

I always thought it was phrased in a rather silly way. As the OP points out, the only position information you have comes from an IRS or FMC, which is also navigating the aircraft; what's the point of plotting this?

Practically, it might help to pick up a gross error from an incorrect waypoint entry if the plotted position is off your intended track. Otherwise, you have no way of knowing that you are/are not where the aeroplane *thinks* you are...