stilton
All modern jet transports still use INS, it's output is used for more than just navigation, e.g. Attitude indicator, vertical speed input and others.
GPS (and other sources) merely update and refine the INS position.
I am sure Concorde would have done the same.
Actually not technically correct mate. The generation(s) of aircraft after Concorde does not use INS as such at all. They either use an Inertial REFERENCE System (IRS) or an Air Data and Inertial Reference System (ADIRS). In both cases inertial data, such as attitude, present position, heading (both true and SYNTHESISED magnetic) acceleration data etc. are
output to various user systems. (eg. FMS, EFIS, Autopilot etc.). Wind data, being a function of True Air Speed (TAS) and Ground Speed (G/S)requires in the IRS case TAS data to be input into the IRS from an Air Data Compter, whereas in the ADIRS case we can have muliple ADCs/IRUs effectively crammed into one box, and so wind is kept 'in house'. In either case the autopilot steering signals (LNAV/VNAV) come from the FMS and NOT the IRS. (If you like you could say that an INS knows where it is and where it wants to go, where an IRS just knows where it is and hasn't a CLUEwhere it's going to. In all cases GPS data is fed into the FMS itself, as 'just another input'.
Although Concorde HAD no GPS, (The most difficult part was always finding a part of the upper fuselage where chunks could be cut out for locating antennae) it was coming! EGPWS was being mandated, which required a simplex GPS antenna mount, and GPS updating for the INS was being seriously looked at. In the first case, the EGPWS requires accurate present position to check agaings it's terrain database for known obstacles and the latter case was because the Concorde INS navigational accuracy fell outside of future (now actually) long range navigational accuracy requirements.
Sorry for such a long winded blurb, but I've been away for a while and am gradually looking back over our wonderful thread to see if there is anything I can contribute to/prattle on about.