This happened to Henri Riza during his first operational mission:

12 September 1944

Thirty seven aircraft from this command took off at 07.30 hrs for the target at Brux-on-Most, Czechoslovakia. The lead group, led by Col Hall, attacked the primary target, blind and unobserved and the high and low groups attacked targets of opportunity. There was some enemy fighter activity but not many were seen. There was considerable battle damage to our aircraft, caused by flak. One of our aircraft has not reported in, Lt McMullen, 533rd,  aboard 42-40007, but it is thought he landed in France with one crewman KIA and two cases of frostbite.

 Mickey operators flying on yesterday's mission flew across the Siegfried and Maginot Lines in the neighborhood of Patton’s Third Army. They reported that the radar picked up thousands of tanks on the American side and relatively few on the German side.

 15 September –

 The recent missing 553rd pilot and crew, Lt Donald  P.  McMullen, was flying with an entirely new crew on the mission to Czechoslovakia, which was designated more to draw enemy fighters than for any particular bombing mission.

 His ship, a B-17G called  HONEY, had been flying at 22,000 ft for some 2½ hrs. Oxygen checks were being made every 15 minutes. The radio operator’s microphone was not working and he had been relaying his oxygen checks to the waist gunner. The radioman answered his oxygen check before the I.P. and then turned around to throw out chaff. He failed to answer his oxygen check 15 minutes later.

The waist gunner, Sgt Meyers J. Barker, was asked to investigate and when he failed to report in, the ball turret man, Sgt Lydell A. Hayes, was ordered to investigate. When in another five minutes neither of these men reported, the engineer went back to investigate, and found all three men unconscious. The radioman Sgt Joseph J. Charkowski, was lying on the floor by the outlet into which he throws the chaff, his mask was off and the face end was disconnected from the oxygen outlet.

The engineer put his mask on Charkowski’s face, connected the hose and turned on the emergency oxygen supply, and the radioman made an immediate recovery and after a short rest period was able to resume his duties as a radio operator. He received a frostbite of the left side of face and cheek, moderate severity.

Waist gunner Hayes was lying at the entrance to the radio operator’s entrance and his mask was off his face and completely disconnected from the G-1 oxygen bottle which was lying beside him. He had taken off his right glove and his hand was frostbitten. The engineer placed his mask on Hayes’ face, connected him to the oxygen outlet and he made a full recovery and was placed in the radio room under protective covers. The engineer’s own bottle was running low about this time and he went back and got the tail gunner to help him and the bombardier came back later.

He found the ball turret gunner lying unconscious under the right waist gun, his mask was off his face and disconnected and full of frozen vomitus. It was disconnected from a full G-1 walk around bottle lying beside him.  A mask was placed on this man’s face, emergency oxygen given and artificial respiration which was continued for approximately 1½ hrs on the ship and later on the ground without signs of life returning.

The radio man did not remember what happened after he started to throw out chaff; the waist gunner did not remember what happened after he started forward with the walk around bottle.

The ship left the formation about 10 minutes after the discovery of the unconscious men and dove 1,700 ft per minute at 250 mph to 4,000 ft and then returned over the greater part of Germany, including the Siegfried Line, at this altitude without enemy interference. They landed at a fighter airfield inside of France where the medical officer, after giving artificial respiration to the ball turret gunner, pronounced him dead, and recommended that they take these man to another airfield near Paris, which was done.

The radio operator had a frostbite on the side of his face, moderate severe, and the waist gunner had frostbite, severe, of the right hand. It is estimated that the radioman was unconscious for more than 25 minutes, and the waist gunner for not more than ten, and no more than 15-20 minutes elapsed before oxygen and artificial respiration was given to the ball turret gunner. The latter had been drinking heavily the night before and had had not more than an hour’s sleep prior to the mission.

The cause of the three anoxic incidents was personnel failure. All masks and ship connections had been checked just a few days prior to the mission by the equipment officer. They were all equipped with the new M-45 modification with the quick-disconnect which makes it virtually impossible for the connections to come apart if inserted at all. The oxygen system of the plane was checked after it landed and this base and was found satisfactory. The engineer on this ship who had the same training as the other crewmen was questioned and appeared to have adequate training and possessed and adequate knowledge of oxygen equipment and its use.

Lt McMullen landed his ship at an airfield near Paris and reported that this fighter group was, as the English put it, “highly browned off”. It appeared that three of their loaded gas tanks were on the way to the field when some of General Patton’s men saw them. As a result, gas, gas tanks etc, disappeared and have not been seen since. But the present gas supplies are being flown in by several stripped down B-17s and B-24s.

Additional evidence of personnel failure in this group came to light with the capture of the personnel records of the German Stalag Luft where American prisoners are interrogated. From these records it was found that captured members of every one of the squadrons had given extensive information to the enemy regarding the formations, personnel and lectures, secret radio information and allied subjects. It is interesting the records revealed that flying personnel from practically every squadron in the ETO and one flyer from the aircraft carrier “Ranger” has divulged significant information to the Germans. There was no reason to believe that personnel had been receiving any pressure when this information was given out.