How long we can run after "brake pad worn sound" comes

[Dhaham]

Dear Experts

Suppose when we are in the middle of a long trip, if we heard the sound coming from brake pads (to indicate that brake pads are worn and have to be replaced), how many kilometers can we drive without damaging the brake disk? Specially when we are at outstations,  we may not be able to find a genuine brake pad set from near by shops. So, is it ok if we drive the car home under this condition?

[Nishan.dj]

Meaning of sound is touching 2 metal together. AFAIK, it should be replaced on the spot. Else you will have to paste the discs.

[tux]

AFIK brake disk is already damaged when you start noticing brake grinding noise.  

[tiv]

in Sri Lanka we call a 100km trip a long trip, of course it takes time, in the Middle East and the west some people do 1000km a day, of course at 100kmph or more, hence a brake pad replacement is not mandated to be done roadside or as an emergency, but needs attention 

Thus, 
About 1000km can be managed, the high pitched sound is made by a metal device , more or less a small strip, built to touch the disc when the pads are near replacement, if you ignore this though, eventually that bit will also wear out  and fall off.,and it will be pad top lining on disc and eventually caliper edge on disc, 

also some brands the pad has a noise making material sandwiched in to the the lower parts so that once u wear the good bit off, it gets noisy all over,

Some Euro makes’ pads have electrodes in the middle of the pad, once worn, the electrode is exposed and it grounds a bulb on the dash, primitive tech but useful.

Don’t expect any of the above If you use non oem pads, 

Edited October 10, 2019 by tiv

[Davy]

The squealing noise progressively gets worse in most cases. It's heard initially only when you step on the brakes and then if you drive like that continuously, it's heard all the time. 

So if your squealing is heard only when you step on the brakes, it's probably okay to complete your journey and carry out the repair later. Agree with @tiv on this. The metal shims that cause this "warning noise" doesn't easily cause the rotors to wear out just like that. Certainly not within a 100km.

Having said that, driving with worn out brakes is never a good idea. Get the brake pads replaced as soon as you possible. 

Edited October 14, 2019 by Davy