B777- alternate and reserve braking

[Frying Dutchman]

Hi gentlemen,

How would you handle a loss of hydraulic situation in a B777 that leads to loss of normal braking, would you request for a tow truck to standby by the runway? I know that it's a must request for one when you have loss of nose steering ability or when there is a Reserve brakes/steering eicas msg. So would anyone do the same when you have alternate brakes remaining?
Did a search but could not find much and Boeing manual does not mention much either. Thanks in advance.

FD

[flightleader]

From what I know, reserve braking is an auto function build inside alternate braking.When the demand for braking is high,a valve would automatically shut off the supply to the steering.Since the crew had no control over this system,he wouldn't know when the steering would be shut off.Thus, would you attempt to taxy if you're not too sure if the steering works? Well, after all the hastle of putting the baby safely on the ground,why risk driving it onto the grass?:}

[Frying Dutchman]

Yup I agree with you that it's better to call for the tow truck, will you do the same when you have alternate brake? I believe reserve brakes are the last of your braking ability left when the hydraulic ran out. I am confused by all these terms, sorry!
Thanks for the reply

[gas path]

Loss of normal brakes would be a loss of the right system hydraulics so could you not continue to taxi as the system will default to centre system where the (normally running) ACMP's will supply alternate brakes? Steering as you know comes from the centre so that's not a issue.
If you are down to Reserve brakes there is a loss of both right and centre hydraulics, a loss of centre system (reading 0.0 on EICAS) gives just over a gallon remaining as 0.0 is stack pipe level, and the isolation valves close at about 0.4.
The reserve brakes/steering EICAS message indicates that brakes or steering may not be available.... hence the need for a tow.