Altitude bust. - NASA ASRS

Attributes
ACN	291811
Time
Date	199412
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : cll
State Reference	TX
Altitude	msl bound lower : 19000 msl bound upper : 20000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu
Operator	general aviation : personal
Make Model Name	M-20 K (231)
Operating Under FAR Part	Part 91
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute airway : zhu
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 25 flight time total : 3990 flight time type : 260
ASRS Report	291811
Person 2
Affiliation	Other
Function	observation : passenger
Qualification	other other : other
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I don't generally operate above 12000 ft due to the bother of using oxygen. However, this day the winds aloft were better at FL230. So, I filed a flight plan and asked for FL230, during the climb out from austin we used the oxygen saver cannulas until we reached about 18000 ft. My wife has multiple sclerosis and is handicapped, so I had to help her change from the cannula to the face mask. The aircraft was on autoplt but I was getting a fair amount of chatter from ATC and engine management is complex on a mooney 231. At that time, I was beginning to feel like I was getting overloaded and asked ATC to allow me to stop my climb at FL190. They granted my request and I leveled off at FL190 and put the autoplt on altitude hold. Now I began to struggle with the cheap plastic face mask. They were cold and stiff and did not seem to be sealing on our faces enough to inflate the bag attached to them. As I struggled with mine and my wife's I began to feel light- headed myself. I got back on my cannula and then noticed that I was about 400 ft off my altitude and the vertical speed showed a descent. Somehow the autoplt had dropped the altitude hold function. My immediate reaction was to stop the descent and climb back to altitude. However, I was confused, and should have read my altimeter better because I was in fact 400 ft high and should have descended. About a min later ATC called me and ask me confirm my altitude. I responded with FL190 and then realized that I was in fact right on FL200. I immediately descended to FL190 and stayed there for the rest of the flight. I blamed this incident to my human error but I feel that a big contributor is the fact that no one makes what I consider a really good face mask for the turbocharged aircraft to use above FL190. One is needed that seals well to the face, is not affected by the cold, and has a built-in microphone. Another factor is the design of the altimeter. It is easy to misread and everything looks so neatly lined up at FL200.

Original NASA ASRS Text

Title: ALT BUST.

Narrative: I DON'T GENERALLY OPERATE ABOVE 12000 FT DUE TO THE BOTHER OF USING OXYGEN. HOWEVER, THIS DAY THE WINDS ALOFT WERE BETTER AT FL230. SO, I FILED A FLT PLAN AND ASKED FOR FL230, DURING THE CLBOUT FROM AUSTIN WE USED THE OXYGEN SAVER CANNULAS UNTIL WE REACHED ABOUT 18000 FT. MY WIFE HAS MULTIPLE SCLEROSIS AND IS HANDICAPPED, SO I HAD TO HELP HER CHANGE FROM THE CANNULA TO THE FACE MASK. THE ACFT WAS ON AUTOPLT BUT I WAS GETTING A FAIR AMOUNT OF CHATTER FROM ATC AND ENG MGMNT IS COMPLEX ON A MOONEY 231. AT THAT TIME, I WAS BEGINNING TO FEEL LIKE I WAS GETTING OVERLOADED AND ASKED ATC TO ALLOW ME TO STOP MY CLB AT FL190. THEY GRANTED MY REQUEST AND I LEVELED OFF AT FL190 AND PUT THE AUTOPLT ON ALT HOLD. NOW I BEGAN TO STRUGGLE WITH THE CHEAP PLASTIC FACE MASK. THEY WERE COLD AND STIFF AND DID NOT SEEM TO BE SEALING ON OUR FACES ENOUGH TO INFLATE THE BAG ATTACHED TO THEM. AS I STRUGGLED WITH MINE AND MY WIFE'S I BEGAN TO FEEL LIGHT- HEADED MYSELF. I GOT BACK ON MY CANNULA AND THEN NOTICED THAT I WAS ABOUT 400 FT OFF MY ALT AND THE VERT SPD SHOWED A DSCNT. SOMEHOW THE AUTOPLT HAD DROPPED THE ALT HOLD FUNCTION. MY IMMEDIATE REACTION WAS TO STOP THE DSCNT AND CLB BACK TO ALT. HOWEVER, I WAS CONFUSED, AND SHOULD HAVE READ MY ALTIMETER BETTER BECAUSE I WAS IN FACT 400 FT HIGH AND SHOULD HAVE DSNDED. ABOUT A MIN LATER ATC CALLED ME AND ASK ME CONFIRM MY ALT. I RESPONDED WITH FL190 AND THEN REALIZED THAT I WAS IN FACT RIGHT ON FL200. I IMMEDIATELY DSNDED TO FL190 AND STAYED THERE FOR THE REST OF THE FLT. I BLAMED THIS INCIDENT TO MY HUMAN ERROR BUT I FEEL THAT A BIG CONTRIBUTOR IS THE FACT THAT NO ONE MAKES WHAT I CONSIDER A REALLY GOOD FACE MASK FOR THE TURBOCHARGED ACFT TO USE ABOVE FL190. ONE IS NEEDED THAT SEALS WELL TO THE FACE, IS NOT AFFECTED BY THE COLD, AND HAS A BUILT-IN MIKE. ANOTHER FACTOR IS THE DESIGN OF THE ALTIMETER. IT IS EASY TO MISREAD AND EVERYTHING LOOKS SO NEATLY LINED UP AT FL200.

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.