EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Weather / Turbulence
Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
While we were handling a radar failed indication; the FMS message 'COMPARE FUEL QUANTITY' appears on the FMS. The First Officer and I agreed that it was probably erroneous but it could be a fuel leak. We ran the QRH for fuel leak. The QRH says: (NOTE: An unexpected difference between the total fuel quantity indicated on EICAS and the total fuel quantity indicated on the FMS Fuel Management page may indicate a fuel leak condition.) We declared an emergency and Landed at the nearest suitable airport. After crash and rescue confirmed that we did not have a fuel leak; we taxied to the gate and wrote up the discrepancies.
Since there were thunderstorms along our route of flight; the captain and I decided to advise ATC of the failure and asked if they could vector us around the thunderstorms since our radar display was not accurate. A few minutes later ATC gave us new routing to bring us around the back side of the weather. We were then told by ATC to expect holding as no aircraft were landing due to thunderstorms. After running the QRH procedure for the situation; we broke out of the clouds and were able to remain VMC and visually avoid the convective activity. We were told by ATC that planes were now landing and to disregard holding.
The flight crew of an ERJ-170 responded appropriately to a 'Compare Fuel Quantity' ECAM message; declared an emergency and landed at the nearest suitable airport. A concurrent failed weather radar; and the presence of convective weather; turned out to be surmountable complicating factors.