An air carrier pilot did not put on his oxygen mask when the other pilot left the cockpit.

Attributes
ACN	224953
Time
Date	199210
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : tph
State Reference	NV
Altitude	msl bound lower : 41000 msl bound upper : 41000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : atp pilot : private pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 10800 flight time type : 1000
ASRS Report	224953
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : far other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While in cruise, the first officer left cockpit to go to forward lavatory to use the facilities. Remained out of cockpit for approximately 2 mins. Captain failed to don eros oxygen mask during this time. Air traffic controller occupied the jump seat.

Original NASA ASRS Text

Title: AN ACR PLT DID NOT PUT ON HIS OXYGEN MASK WHEN THE OTHER PLT LEFT THE COCKPIT.

Narrative: WHILE IN CRUISE, THE FO LEFT COCKPIT TO GO TO FORWARD LAVATORY TO USE THE FACILITIES. REMAINED OUT OF COCKPIT FOR APPROX 2 MINS. CAPT FAILED TO DON EROS OXYGEN MASK DURING THIS TIME. AIR TFC CTLR OCCUPIED THE JUMP SEAT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.