Twelve O'Clock High

In 1949, American attorney and former U.S. Army Air Forces officer Harvey Stovall (Dean Jagger) is vacationing in Great Britain when he spots a familiar Toby Jug in an antique shop window. He asks the proprietor where he bought the jug and he is told that it came from Archbury, which is the location of the former Royal Air Force Station Archbury and USAAF station where Stovall served with the 918th Bomb Group during World War II. Convinced that it is the same jug, he buys it and journeys by train and bicycle to the ex-RAF airfield at Archbury, now abandoned and used as pasture, but with the runways, taxiways, control tower and other buildings still standing. As Stovall relives memories of the place, the scene flashes back to 1942 and the main plot begins.Having recently arrived and been thrown into action, the 918th has gained the reputation of a "bad luck group" suffering from poor morale. One reason is the U.S. strategy of daylight precision bombing and the corresponding losses to German anti-aircraft fire and Luftwaffe fighter aircraft. In addition, their commander, Colonel Keith Davenport (Gary Merrill), has become too close to his men to instil adequate discipline. When he is ordered to fly a mission at low altitude to increase accuracy, Davenport rushes to headquarters and confronts his friend, Brigadier General Frank Savage (Gregory Peck), the Assistant Chief of Staff for Operations. His behavior prompts Savage to go to Major General Patrick Pritchard (Millard Mitchell), commanding general of VIII Bomber Command, and tell him that that he feels Davenport might crack under the strain. Pritchard eventually relieves Davenport of command and the 918th is given to Savage.In order to address discipline problems, Savage deals with everyone so harshly that the men begin to detest him. Upset by the contrast of Savage's stern leadership, all of the 918th's pilots apply for transfers. Savage asks the Group Adjutant, Major Stovall, to delay processing their applications to buy him some time since, as an attorney in civilian life, Stovall knows how to use "red tape. When the 918th resumes combat flying with greater success after hasty refresher training, the men begin to change their minds, especially after Savage leads them on a mission in which the 918th is the only group to bomb the target and have all of the aircraft return safely.The word gets around that Pritchard personally chewed Savage out for his claim of "radio malfunction" as an excuse to ignore the recall order. But rather than incurring any form of punishment for this disobedience, Savage persuades Pritchard to recommend the group for a Distinguished Unit Citation. When the Inspector General arrives to check out the unrest, Savage is packing ready to go, but the pilots withdraw their requests to transfer. Savage also softens his attitude towards the men as he becomes more closely involved with them and is warned about the consequences by Keith Davenport on one of his visits.As the air war advances deeper into Germany, missions become longer and riskier, with enemy resistance intensifying. Many of Savage's best men (including Bishop and Cobb) are shot down or killed. Pritchard tries to get Savage to return to a staff job at VIII Bomber Command, but Savage refuses because he feels that the 918th is incapable of performing without him. Reluctantly, Pritchard leaves him in command. However, before a particularly dangerous raid, Savage becomes disoriented and erratic; unable to haul himself up into his B-17, he has to be relieved. While waiting for the groups return, Savage becomes catatonic. Only as they fly back relatively unharmed after destroying the target, does he regain his composure and fall asleep.The story then returns to 1949 and Stovall, who leaves the Toby mug on the fireplace mantle of the abandoned airfield's officers' club and pedals away on his bicycle.

Question: What did Savage claim to have malfunctioned when ignoring the recall order?
Answer: Radio