FUEL QTY LOW is a CAUTION (Amber) and thus a Aural waning with the Beeper.
Low Fuel
Low Fuel Operations In-flight
A low fuel condition exists when the EICAS message FUEL QTY LOW is displayed.
Approach and Landing
In a low fuel condition, the clean configuration should be maintained as long as possible during the descent and approach to conserve fuel. However, initiate configuration changes early enough to provide a smooth, slow deceleration to final approach speed to prevent fuel from running forward in the tanks.
The FUEL QTY LOW NNC specifically calls for a flaps 20 approach and landing rather than a normal landing configuration as in other models. Testing and analysis shows that elevator authority at flaps 30 approach speeds is not adequate to enable the crew to successfully flare the airplane for landing in the unlikely event both engines failed in the landing configuration.
Runway conditions permitting, heavy braking and high levels of reverse thrust should be avoided to prevent uncovering all fuel pumps and possible engine flameout during landing roll.
Go-Around
If a go-around is necessary, apply thrust slowly and smoothly and maintain the minimum nose-up body attitude required for a safe climb gradient. Avoid rapid acceleration of the airplane. If any wing tank fuel pump low pressure light illuminates, do not turn the fuel pump switches off.
FCOM/FCTM make no mention of FUEL QTY LOW triggers.
From B777 Fault Isolation Manual: 28-22-00-810-846.
The EICAS message FUEL QTY LOW will show when there is less than 4500 LB (2000 KG) of fuel the left or right main fuel tank.
NOTE: The EICAS message will dissapear when the fuel quantity in each main fuel tank has increased to 4700 LB (2200 KG)