Air Corps. The Baker Board included all five military members of the earlier Drum Board, four of them senior Army ground force officers who tightly controlled the agenda and scope of the board's investigation to prevent it from becoming a platform for advocating an independent air arm. Of the 12 members, only three were Air Corps advocates. Not surprisingly, the Baker Board endorsed the earlier findings of the Drum Board, supporting the status quo that the Air Corps was an auxiliary force of the Army and opposing the Air Corps becoming a separate service equal to the Army and Navy. It rejected the threat of air attack as a major threat to the national defense or the need of a large air force to defend against it. It opposed any expansion of the Air Corps until the needs of the Army as a whole had been addressed. It did however reiterate the Drum Board's recommendation for the immediate activation of the GHQ Air Force, placing under it all air combat units within the continental United States. This provided another, limited step toward an autonomous air force, but also kept authority divided by maintaining control of supply, doctrine, training and recruitment under the Chief of the Air Corps, and airfields in the control of corps area commanders. Within the Air Corps, instrument training was upgraded, radio communications were greatly improved into a nationwide system that included navigation aids, and budget appropriations were increased. The Air Corps acquired the first six Link Trainer flight simulators of a fleet that would ultimately number more than 10,000. The operation also demonstrated the complete obsolescence of open-cockpit aircraft in military operations, leading to increased development of modern types in the second half of the decade, most of which served successfully in World War II. Among the fallout of the scandal was the retirement under fire of Foulois as Chief of the Air Corps. He had been called to testify before the Rogers subcommittee on aviation of the House Committee of Military Affairs during the scandal. Chairman William N. Rogers of New Hampshire was suspicious of Foulois for negotiating aircraft contracts instead of assigning them to the lowest bidder, and during his testimony the Chief of Air Corps had been flamboyant and careless with hyperbole. In the wake of the mail fiasco, Rogers charged him with several violations of law and ethics, including making misleading statements