Flight crew reported difficulties with the FMS while conducting approaches into mry below published ...

Attributes
ACN	1549542
Time
Date	201806
Local Time Of Day	0001-0600
Place
Locale Reference	MRY.Airport
State Reference	CA
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	EMB ERJ 170/175 ER/LR
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

Narrative:

Flight to mry. We had a radar altimeter MEL which kept us from going lower. Weather was reported below our minimums. FMS on first approach to an ILS 10R at myr started acting up; showing 177 magenta speed when it should have shown what was in the box; at least 230. Additionally the FMS did not sequence into the approach and we went missed approach to alternate for more fuel. Plus approach was below minimums anyway and everyone ahead of us had gone missed. On our second attempt; runway changed enroute; but weather was better. We started the descent for the approach. As we got closer to the fix; the FMS wouldn't sequence and showed same speed error as before. The captain could not sequence the box or fix the situation. We were VMC; but if we continued into the approach we would have been IMC and low with an FMS acting up. We decided to go with the procedure turn instead of turning in; which coincided with the FMS doing the only thing correctly. I added power to climb back up because we also realized we were lower than the next fix.

Original NASA ASRS Text

Title: Flight crew reported difficulties with the FMS while conducting approaches into MRY below published minimums.

Narrative: Flight to MRY. We had a Radar Altimeter MEL which kept us from going lower. Weather was reported below our minimums. FMS on first approach to an ILS 10R at MYR started acting up; showing 177 magenta speed when it should have shown what was in the box; at least 230. Additionally the FMS did not sequence into the approach and we went missed approach to alternate for more fuel. Plus approach was below minimums anyway and everyone ahead of us had gone missed. On our second attempt; runway changed enroute; but weather was better. We started the descent for the approach. As we got closer to the fix; the FMS wouldn't sequence and showed same speed error as before. The Captain could not sequence the box or fix the situation. We were VMC; but if we continued into the approach we would have been IMC and low with an FMS acting up. We decided to go with the procedure turn instead of turning in; which coincided with the FMS doing the only thing correctly. I added power to climb back up because we also realized we were lower than the next fix.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Flight crew reported difficulties with the FMS while conducting approaches into mry below published minimums.