Mr. Robin also said that 40 cellphones had been found at the crash site. “These phones are in a very, very damaged condition, which will make exploiting them very hard,” he said.

The discovery of the second black box, the flight data recorder, should enable the authorities to determine more precisely what actions Mr. Lubitz took to put the plane into its fatal descent and to prevent the captain from re-entering the cockpit.

Prosecutors in Düsseldorf declined to release any information on the exact search terms found on Mr. Lubitz’s iPad. They said such details must remain confidential until all the evidence had been evaluated. They also said they were working with the local and state police to evaluate the documents and electronic devices found in Mr. Lubitz’s apartment. The police spent several hours searching his home last Thursday, removing two moving boxes and large plastic bags full of possible evidence.

Among the items found was the iPad, which prosecutors said contained “personal correspondence and search terms that lead to the conclusion that the device was used by the co-pilot” in the days before the crash.

“Everything that helps to understand better what happened is something we welcome,” Gernot Waha, a spokesman in Frankfurt for Lufthansa, the parent company of Germanwings, said in response to the information provided by the Düsseldorf prosecutors and the discovery of the flight data recorder. He said he could not comment further.

The flight data recorder tracks hundreds of performance statistics from the plane, including its position, speed, altitude and direction. Officials said the recorder would be transported to the offices of France’s accidents investigation bureau near Paris.

Image French rescue workers at the scene of the Germanwings Airbus A320 crash on Tuesday. Credit... Yves Malenfer/French Interior Ministry

An official involved in the investigation said that the recorder’s protective case did not appear to have been significantly damaged, raising hopes that the data contained on its flash memory card would be successfully retrieved and synchronized with the voice recorder recovered soon after the crash. The official, who requested anonymity because the inquiry was continuing, confirmed that the flight data recorder had been found intact.

Last week, searchers found a severely damaged device that they initially believed was the flight data recorder’s external case, leading them to conclude — and President François Hollande to announce — that the recorder’s memory card had been dislodged by the force of the crash. However, the official said that device had subsequently been determined to be an antenna.

Investigators are likely to spend the next several weeks conducting a detailed analysis of the two black box recordings in order to assemble a fuller picture of what happened in the flight’s final moments.

A team of German aviation experts and industry representatives plans to examine whether to introduce changes to cockpit door controls and to the medical assessment of pilots because of the crash, Germany’s transportation minister said Thursday. Investigators believe that Mr. Lubitz prevented the captain from returning to the cockpit by activating security mechanisms, introduced after the attacks of Sept. 11, 2001, that are designed to prevent outsiders from entering and seizing the controls.

A thorough exploration of what changes, if any, could be made to cockpit doors will be one of the first tasks taken up by the German experts, said Alexander Dobrindt, Germany’s transportation minister. He noted, however, that any changes would require consultation with European and international agencies.

Last week, airlines in Germany and elsewhere in Europe rushed to introduce a requirement that two crew members be present in the cockpit at all times, a rule that American carriers have had in place for many years.

Germany is also debating whether to systematically require passengers on flights within Europe to show a piece of personal identification in addition to their ticket before boarding planes. The authorities initially struggled to determine exactly who had been aboard the flight when they ran checks on whether any of the passengers had links to terrorism.