Crj flight crew reports an inadvertent button push while attempting to select heading on the fcp res...

Attributes
ACN	1131086
Time
Date	201311
Local Time Of Day	1801-2400
Place
Locale Reference	TUS.Airport
State Reference	AZ
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	Regional Jet CL65 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Component
Aircraft Component	MCP
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT

Narrative:

We were proceeding directly to lipte intersection maintaining 6;000 feet to join the ILS 11L arrival. At 4 miles prior to lipte I (pilot flying) selected heading mode for the switch to green needles. I inadvertently hit the 1/2 button causing the ILS frequency to disappear in the comm one standby box. I was distracted by this [and] I tried to fix it. During this time the autopilot disconnected. I was fixated on frequency and did not recognize the autopilot disconnected. The pilot not flying asked what was wrong. I got the right frequency and looked up to see we were low for the approach and the GPWS 'too low terrain' alert went off. I applied max thrust and started to climb. ATC also said that they were getting a low altitude alert as well and suggested 6;000 ft per minute vectoring altitude in that sector. We climbed back through 6;000 ft; leveled off and continued to intercept the ILS 11L and continued inbound on the approach. The day was long with weather in the entire southwest. 5 legs; delayed almost every leg. What was a routine ILS was hampered by fatigue and an inadvertent hitting of the wrong button on the comm 1 followed by a fixation on the problem. Fatigue being the cause; a solution is to avoid and recognize it before it hampers safety.

Original NASA ASRS Text

Title: CRJ flight crew reports an inadvertent button push while attempting to select heading on the FCP resulting in autopilot disconnect and the loss of 700 FT. GPWS and ATC both announce the deviation and the Captain returns to 6;000 FT. Both pilots cited a long fatiguing day as contributing to the error.

Narrative: We were proceeding directly to LIPTE intersection maintaining 6;000 feet to join the ILS 11L arrival. At 4 miles prior to LIPTE I (pilot flying) selected HDG mode for the switch to green needles. I inadvertently hit the 1/2 button causing the ILS frequency to disappear in the Comm one standby box. I was distracted by this [and] I tried to fix it. During this time the autopilot disconnected. I was fixated on frequency and did not recognize the autopilot disconnected. The pilot not flying asked what was wrong. I got the right frequency and looked up to see we were low for the approach and the GPWS 'TOO LOW TERRAIN' alert went off. I applied max thrust and started to climb. ATC also said that they were getting a Low Altitude alert as well and suggested 6;000 FT per minute vectoring altitude in that sector. We climbed back through 6;000 FT; leveled off and continued to intercept the ILS 11L and continued inbound on the approach. The day was long with weather in the entire southwest. 5 legs; delayed almost every leg. What was a routine ILS was hampered by fatigue and an inadvertent hitting of the wrong button on the Comm 1 followed by a fixation on the problem. Fatigue being the cause; a solution is to avoid and recognize it before it hampers safety.

Data retrieved from NASA's ASRS site as of July 2013 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.