Unusual brake noise!

[Jerry: BLACK 85 GT h/b]

The other day as I drove into our apartment, I lost the brakes! Instead of the usual simple loss, I also heard a fairly loud 'WHOOSH' sound from under the dash!
The pedal went almost to the floor, but did allow me to slow down. I certainly can't drive on public roads, so the car's been up on stands while i try to locate the problem.
My son suggested the 'plunger' at the brak pedal may be the culprit. I had my wife apply the brakes while I listened under the hood. There was no sound from the power booster vac hose or the unit. Master cylinder has pleant of fluid, and no signs of leaking at any wheel cylinders!

I am now physically limited/disabled, so I can't get into too much of a project. Has anyone else had this problem? Any suggestions? Am I going to have to get a mechanic and pay $$$?

[KS 82 GT]

I think your master cylinder failed. The 'whoosh!' makes me think booster, but I would think that if the master cylinder after building a bit of pressure before failing that it might make that noise. If it's the master cylinder, the good news is that they're fairly inexpensive. It's not a difficult job and other than bleeding everything when you're done, can be handled entirely from under the hood. If you have a favorite mechanic, then they can handle it for a reasonable price, otherwise check around.