IFA mode in stock Task for Challenger 1989 Campaign doesn't work?

[Polonsky]

The INS were initialized as IFA mode by default and stays in the QUAL: 0.5 OK state and won't continue to work as POS/AINS in the stock Campaign (Both the vanilla version and the supercarrier version). In order to make it work I have to turn back to NAV mode again upon each mission start otherwise the navigation and weapon designation will degrade at unacceptable rate as the flight progress advances. Is it a bug or what is the correct way to work with IFA.

Edited September 7 by Polonsky

[Akiazusa]

iirc,u switch to IFA only if there is gps available so the GPS can keep updating ur INS position,since ur mission is in 1989,so no gps in ur mission,u need to keep it in NAV after alignment. But if it initialized as IFA mode for hot/inflight start by default in non-gps era I think that's a bit odd.

Edited September 7 by Akiazusa