Concerns from a September 2010 UPS crash over appropriate use of oxygen masks by pilots have prompted the US National Transportation Safety Board (NTSB) to issue new recommendations over proper mask use.
The UPS Boeing 747-400 freighter crashed in Dubai after a fire broke out on the main deck shortly after departure.
During its assistance in the accident investigation NTSB determined that pilots have difficulty with the combination of oxygen and goggle sets used by the pilots on the aircraft involved in the crash. In addition to ensuring proper settings on the mask, pilots also must don goggles and open a vent selector on the mask to rid the goggles of smoke.
In tests following the crash at UPS and Boeing training facilities, some participating pilots had challenges in ensuring the mask was fitted properly and donning the mask-goggle set. Participants also told investigators it was difficult to change a selector position on the mask from a predetermined setting to an alternate condition to provide constant pressurised airflow for an emergency situation.
"When the oxygen mask/goggle set is donned, the locations of the normal/100% switch and the emergency selector on the regulator, in addition to the smoke vent selector on the mask, are not visible to the pilot, and, therefore, must be located and activated only by feel," said NTSB.
UPS in July of this year stated it planned to retrofit its Boeing aircraft fleet with full-face oxygen masks with integrated smoke goggles, ahead of NTSB issuing a recommendation to the FAA on 20 September to require all general, business, charter and scheduled operators to install the full face masks on their aircraft.
NTSB also expressed concern over pilots being properly trained on the mask/goggle combination until operators complete installation of the full-face oxygen masks.
In the UPS curriculum, said NTSB, pilots are introduced to the oxygen masks during the first simulator session but are only instructed on how to pre-flight the system. During a sixth session, pilots do have the opportunity to don the mask/goggle set, but "according to interviews with the simulator instructor who trained the UPS6 [accident flight] first officer, while students would don the oxygen masks it was considered 'rare' for a student to need to don the smoke goggles during the simulator session", NTSB explained.
The agency is recommending during initial and recurrent training that pilots practice hands-on use of the sets including selecting the emergency setting and venting of the smoke goggles.
NTSB also suggested FAA require aircraft-specific training on establishing and maintaining internal cockpit communications. Citing a previous incident in 2009 involving a United Airlines aircraft making an emergency landing in Iceland after encountering smoke in the cockpit, NTSB said the crewmembers donned their masks/goggle sets, but experienced challenges in establishing and maintaining communications.
"The entire process of donning goggles, the use of oxygen masks, pushing all the different buttons and toggles to communicate with all the people involved was very frustrating at times," said the United first officer involved in the incident. "Between the goggles scratching my glasses and the smoke film in front of them too, it was hard to see at times. Too many items have to come together for this setup to work."
NTSB's final two recommendations from the UPS and United investigations relate to leaving masks set at the 100% setting during long flights. Some pilots switch the system from 100% to normal to extend oxygen supply when one crew member leaves the cockpit for a break.
"The NTSB is concerned that, while no requirement exists to operate the mask at 100% in flight during normal conditions, the practice of setting a mask to normal, particularly during extended cruise with multiple crew member breaks, increases the risk that a mask will be restowed in the normal position and not set properly to use for a non-normal event," the agency stated.
Pilots participating in tests after the UPS accident stated switching the mask from normal to 100% during an emergency "was only possible with practice and focused concentration", said NTSB.