Three area supervisors for Spanair face involuntary manslaughter charges in connection with the August 20, 2008 air crash at Barajas International Airport that killed 154 passengers, a judge ruled Wednesday.

Madrid investigating Judge Javier Pérez has subpoenaed José Antonio V., the on-duty chief of operations at the time; David T., maintenance supervisor; and Alejandro S., quality control supervisor. The three Spanair employees will have to appear before the judge later this month to give testimony. The airline's maintenance chief, Jesús T., who has already been targeted in the inquiry, will also have to testify before Pérez this month.

Pérez based his charges on two reports, including one that was produced by a French expert in air disasters. Canaries-bound Flight JK5022 crashed near the runway just after takeoff, killing 154 and injuring 18 after its flaps failed to open properly.

Experts blamed human error on the part of the mechanics for the disaster, after they disconnected a heater that is designed to prevent ice forming on a sensor during flight. This prevented the TOWS alarm system, which should have warned pilots of the fault, from activating.

Pilar Vera, president of the victims and survivors association, had pushed for the three defendants to be charged. "We did it in honor of those who are no longer with us and in the hope that it will never again occur," she said.

The experts' reports have also blamed Boeing and aviation authorities for contributing to the accident by not addressing the heat-sensor problem following two other previous accidents.

The MD-82 has a history of failures, including a crash in Detroit that killed 154 people in 1987 and another in Indonesia in 2005 that left 25 dead. "We have dark suspicions that this could happen again one day," said Vera.