It was the worst of three black-outs during a week of mounting chaos that has caused spiralling delays in all flights, and cancellations in the peak pre-Christmas season. As the weekend approached, the situation worsened. Mr Salgado announced that the nearby military airbase at Torrejon would be commandeered for civilian planes.
The base, destined for Nato use when Spain becomes a full member next year, is expected to start taking the overspill within a fortnight. Passengers will have to check in at Barajas then be bussed along 8km of choked motorway. Torrejon's runway is at right angles to that of Barajas, so flight paths will intersect.
Tuesday's black-out was caused by a fire after a workman drove an excavator's drill through a 14,000-volt high- tension cable. Back-up generators and other emergency measures failed to operate. On Thursday an Iberia plane overran the runway and stuck in the mud, causing panic when an exit door stuck.
Madrid's only airport is 65 years old, has two congested runways, and work on the third is five years overdue. Regional authorities are slowly waking up to the need for a second airport.
The state airline, Iberia, fiercely opposes a second airport, insisting a single connecting point is vital for its international network. Anyone who uses Barajas regularly can testify to Iberia's clout. Flights from far cheaper private carriers are routinely bumped from their slots by Iberia.
Mr Arias Salgado blames the previous government for the chaos, saying the Socialists delayed a report on the environmental consequences of expansion for two years. Josep Borrell, the former Socialist Public Works Minister, criticised Mr Arias Salgado for his "irresponsibility and manifest inability to confront the problems of air traffic".