INS reverts to status 90 mid flight, HSI out as well

[Bence Csordas]

Hi, i had like 3 good flight, but now i cant finish a flight, because one or all of the INS freeze on position, and when i check status its back on 90, ALERT flashing, and i cant do anything onwards. Any suggestion what can be wrong, or how can I help myself on this? Also it seems, HSI is out as well, because when i try to finish the flight with radio navigation it doesnt change.. Rotates, but apart from that, radio navigation doesnt work either, and it not rotate to the radio beacon just to 180-360. Not even show the ILS course deviation,  however at least the plane captures it.

[Delta064]

My INS1 STS has just dropped to 90 in flight. POS is frozen and I've lost all other functions (e.g. TK/GS, DIS/TIME), Tx CHG no lomnger works however, the autopilot does still seem to be following the route correctly. INS3 (FO's?) is still working fine but it's my understand the AP only works from INS1 (CAPT's). I've just loaded in the 2nd batch of WPTs 1-9 so I'll see if it continues to guide correctly...

Correction - INS mode on the AP had dropped out. Tried reengaging at its returning the A/C to the frozen leg, so I can no longer use INS for navigation, less than a quarter of the way into a transatlantic crossing...

I appreciate simulating non-normals, but you usually get to choose! 😉

Edited 5 hours ago by Delta064

[MD82]

I believe the INS's bug out as soon as ANY type of electrical switching occurs. Which I don't believe should be the case. They have a battery I believe for exactly this purpose. To keep its status during transient power changes.