LANGLEY AIR FORCE BASE, Va. — Defense Secretary Gates launched the Air Force in a new direction yesterday by announcing an unusual choice as the service’s next uniformed chief and by declaring an immediate halt to personnel reductions that he said had put the Air Force under too much wartime strain.

Before flying here to explain his moves to airmen and their commanders, Mr. Gates recommended that President Bush nominate General Norton Schwartz, a 35-year veteran with a background in Air Force special operations, as the new Air Force chief of staff, replacing General Michael Moseley, who has been sacked.

In a sweeping shake up, Mr. Gates also formally sent former Air Force official Michael Donley’s name to the White House to be the next secretary of the beleaguered service. Mr. Bush quickly announced he would nominate Mr. Donley, and designated him as acting secretary until he is confirmed by the Senate.

Mr. Gates said Mr. Donley and General Schwartz were coming in at an important time in the history of the Air Force.

“General Schwartz’s unique set of experiences and accomplishments make him the right officer at this time to lead the Air Force,” Mr. Gates told an audience of several hundred servicemen and Air Force civilians.

Mr. Gates announced on Thursday that he was removing General Moseley from the chief’s job and Mr. Wynne as its top civilian to hold them accountable for failing to fully correct an erosion of nuclear-related performance standards, a concern linked to the cross-country flight last August of a B-52 carrying armed nuclear weapons.