A B737-800 captain upon receiving a descent clearance pushed the alt intervene button which deleted ...

Attributes
ACN	1237104
Time
Date	201502
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Overshoot Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Narrative:

I was flying the leg to ZZZ. We were given the clearance to descend via the arrival and I set 10;000 feet in the altitude window. (Not sure what altitude we are at when given the clearance.) I selected the 'alt intervention' button to start the descent. The machine did not respond so I selected the 'alt intervention' button once again; not realizing/recognizing I was in alt hold and not VNAV. The effect of selecting alt intervention a second time was to delete the crossing restriction of FL240A (at or above fl 240) at fix zzzzz. The ultimate result was crossing fix zzzzz at approximately fl 230; 1;000 feet below the restriction.I've flown this arrival 100;000;000 times with no deviations; which; of course; counts for diddly squat if your not paying attention that one complacent moment!

Original NASA ASRS Text

Title: A B737-800 Captain upon receiving a descent clearance pushed the alt intervene button which deleted the first crossing restriction and caused the aircraft to cross that fix 1;000 feet low.

Narrative: I was flying the leg to ZZZ. We were given the clearance to descend via the Arrival and I set 10;000 feet in the altitude window. (Not sure what altitude we are at when given the clearance.) I selected the 'alt intervention' button to start the descent. The machine did not respond so I selected the 'alt intervention' button once again; not realizing/recognizing I was in Alt Hold and not VNAV. The effect of selecting alt intervention a second time was to delete the crossing restriction of FL240A (at or above FL 240) at Fix ZZZZZ. The ultimate result was crossing Fix ZZZZZ at approximately FL 230; 1;000 feet below the restriction.I've flown this arrival 100;000;000 times with no deviations; which; of course; counts for diddly squat if your not paying attention that one complacent moment!

Data retrieved from NASA's ASRS site 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.

A B737-800 captain upon receiving a descent clearance pushed the alt intervene button which deleted the first crossing restriction and caused the aircraft to cross that fix 1;000 feet low.