B737-700 flight crew experiences loss of airspeed indication and erroneous altitude indication durin...

Attributes
ACN	1175007
Time
Date	201405
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Pitot-Static System
Person 1
Function	Pilot Flying First Officer
Experience	Flight Crew Last 90 Days 303
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 325 Flight Crew Type 12000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Speed All Types

Narrative:

While cruising at FL330; I noticed my altimeter climbing almost 300 feet and my airspeed rapidly falling off. I disconnected the autopilot to ensure no loss of aircraft control. During this period; I confirmed we had not lost any engines and cross checked the captain's instrument panel during my descent back to FL330. I noticed the captain's instruments still read at altitude and on speed so we elected to have the captain fly the aircraft while I ran checklists. We contacted ATC and they reported not seeing any deviation but we requested descent out of rvsm airspace as we had disconnected the autopilot and had conflicting readings on altitude and airspeed. In the descent to FL270; we ran several checklists; airspeed unreliable; probe heat; IAS and altitude disagree; and the eec checklist as the engines had also reverted to the altn mode. Upon reaching FL270; the instruments agreed and we finished the flight with no more problems.

Original NASA ASRS Text

Title: B737-700 flight crew experiences loss of airspeed indication and erroneous altitude indication during cruise a FL330. EEC had switched to soft alternate. The Captain's instruments are determined to be correct and descent out of RVSM is initiated.

Narrative: While cruising at FL330; I noticed my altimeter climbing almost 300 feet and my airspeed rapidly falling off. I disconnected the autopilot to ensure no loss of aircraft control. During this period; I confirmed we had not lost any engines and cross checked the Captain's instrument panel during my descent back to FL330. I noticed the Captain's instruments still read at altitude and on speed so we elected to have the Captain fly the aircraft while I ran checklists. We contacted ATC and they reported not seeing any deviation but we requested descent out of RVSM airspace as we had disconnected the autopilot and had conflicting readings on altitude and airspeed. In the descent to FL270; we ran several checklists; Airspeed Unreliable; Probe Heat; IAS and ALT Disagree; and the EEC Checklist as the engines had also reverted to the ALTN mode. Upon reaching FL270; the instruments agreed and we finished the flight with no more problems.

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.

B737-700 flight crew experiences loss of airspeed indication and erroneous altitude indication during cruise a FL330. Eec had switched to soft alternate. The captain's instruments are determined to be correct and descent out of rvsm is initiated.