False GPWS warning causes medium large transport to climb from 6000 ft to 7300 ft in IMC.

Attributes
ACN	248289
Time
Date	199308
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dca
State Reference	DC
Altitude	msl bound lower : 6000 msl bound upper : 7300
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dca
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 6000 flight time type : 1500
ASRS Report	248289
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

At 6000 ft on assigned heading 180 degrees, GPWS sounded with 'terrain, terrain, climb, climb.' went maximum power and took off altitude and pitched to about 20 degrees (250 KTS). GPWS sounded several more times then silenced. I stopped the climb at 7300 ft. First officer told ATC who said come back down to 6000 ft when able. Although I 'knew' there weren't 6000 ft mountains, I thought maybe I had misread the altimeter or maybe altimeter system had failed. Thinking back, radar altimeter had 'fluttered' up to plus or minus 1000 ft prior (don't know how prior). This occurred about over cia buildings. If they radiate electromagnetic 'stuff' (I'm a business major, not engineering!) that affects our aircraft such that we have to immediately leave assigned altitudes, especially in as congested an area as the dc area, we could certainly have midair collisions (not to mention ATC controllers and pilots with more gray or missing hair). We did tell the controller as soon as possible but with frequency congestion, etc, it took way too long for him to do any controling. I assume the cia would deny everything but just the question to them may make them check internally.

Original NASA ASRS Text

Title: FALSE GPWS WARNING CAUSES MLG TO CLB FROM 6000 FT TO 7300 FT IN IMC.

Narrative: AT 6000 FT ON ASSIGNED HDG 180 DEGS, GPWS SOUNDED WITH 'TERRAIN, TERRAIN, CLB, CLB.' WENT MAX PWR AND TOOK OFF ALT AND PITCHED TO ABOUT 20 DEGS (250 KTS). GPWS SOUNDED SEVERAL MORE TIMES THEN SILENCED. I STOPPED THE CLB AT 7300 FT. FO TOLD ATC WHO SAID COME BACK DOWN TO 6000 FT WHEN ABLE. ALTHOUGH I 'KNEW' THERE WEREN'T 6000 FT MOUNTAINS, I THOUGHT MAYBE I HAD MISREAD THE ALTIMETER OR MAYBE ALTIMETER SYS HAD FAILED. THINKING BACK, RADAR ALTIMETER HAD 'FLUTTERED' UP TO PLUS OR MINUS 1000 FT PRIOR (DON'T KNOW HOW PRIOR). THIS OCCURRED ABOUT OVER CIA BUILDINGS. IF THEY RADIATE ELECTROMAGNETIC 'STUFF' (I'M A BUSINESS MAJOR, NOT ENGINEERING!) THAT AFFECTS OUR ACFT SUCH THAT WE HAVE TO IMMEDIATELY LEAVE ASSIGNED ALTS, ESPECIALLY IN AS CONGESTED AN AREA AS THE DC AREA, WE COULD CERTAINLY HAVE MIDAIR COLLISIONS (NOT TO MENTION ATC CTLRS AND PLTS WITH MORE GRAY OR MISSING HAIR). WE DID TELL THE CTLR ASAP BUT WITH FREQ CONGESTION, ETC, IT TOOK WAY TOO LONG FOR HIM TO DO ANY CTLING. I ASSUME THE CIA WOULD DENY EVERYTHING BUT JUST THE QUESTION TO THEM MAY MAKE THEM CHK INTERNALLY.

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.