Pilot descended 700 ft without ATC clearance.

Attributes
ACN	272495
Time
Date	199405
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : scy
State Reference	TX
Altitude	msl bound lower : 21300 msl bound upper : 22000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Route In Use	enroute airway : zfw
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 225 flight time total : 10000 flight time type : 4800
ASRS Report	272495
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance non adherence : required legal separation other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	flight crew : took evasive action other
Consequence	Other
Miss Distance	horizontal : 2000
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

En route from grand cayman to dallas ft worth on may/xx/94 at XA30 local time, we received a 'hold' at coiax intersection with an expect further clearance time of XE50. The WX in that area was poor. Continuous moderate turbulence, icing. We were having a problem receiving scurry, VOR (scy) due to that, plus large thunderstorm (cell) close to hold fix. After 1 turn in the hold we realized that our fuel did not allow to hold much longer than the 'efc' time. We decided to divert to wichita falls, tx, (ict). We were at FL210. With the WX situation as it was we asked for 'higher.' we were then cleared to FL220. Shortly after level off at FL220 (around the 030 degrees and 20 DME from scurry VOR) (scy) area, we received a TCASII RA. 'Descend,' and the TCASII ivsi indicated a descent of about 2500 FPM. We began our descent. At about FL215 ZFW called to ask about our altitude. We advised that we were in a TCASII RA descent. Another airlines also said 'so is other air carrier number?' on a TCASII advisory. We descended to FL213. After the traffic conflict, we climbed back to FL220 and proceeded on course. At this point, I do not know what could have caused this traffic problem and TCASII RA. My guess is that the other air carrier may have been cleared above us with a high rate or climb or cleared to FL210 with a high rate of climb. Possibly we were both cleared to maintain FL220.

Original NASA ASRS Text

Title: PLT DSNDED 700 FT WITHOUT ATC CLRNC.

Narrative: ENRTE FROM GRAND CAYMAN TO DALLAS FT WORTH ON MAY/XX/94 AT XA30 LCL TIME, WE RECEIVED A 'HOLD' AT COIAX INTXN WITH AN EXPECT FURTHER CLRNC TIME OF XE50. THE WX IN THAT AREA WAS POOR. CONTINUOUS MODERATE TURB, ICING. WE WERE HAVING A PROB RECEIVING SCURRY, VOR (SCY) DUE TO THAT, PLUS LARGE TSTM (CELL) CLOSE TO HOLD FIX. AFTER 1 TURN IN THE HOLD WE REALIZED THAT OUR FUEL DID NOT ALLOW TO HOLD MUCH LONGER THAN THE 'EFC' TIME. WE DECIDED TO DIVERT TO WICHITA FALLS, TX, (ICT). WE WERE AT FL210. WITH THE WX SIT AS IT WAS WE ASKED FOR 'HIGHER.' WE WERE THEN CLRED TO FL220. SHORTLY AFTER LEVEL OFF AT FL220 (AROUND THE 030 DEGS AND 20 DME FROM SCURRY VOR) (SCY) AREA, WE RECEIVED A TCASII RA. 'DSND,' AND THE TCASII IVSI INDICATED A DSCNT OF ABOUT 2500 FPM. WE BEGAN OUR DSCNT. AT ABOUT FL215 ZFW CALLED TO ASK ABOUT OUR ALT. WE ADVISED THAT WE WERE IN A TCASII RA DSCNT. ANOTHER AIRLINES ALSO SAID 'SO IS OTHER ACR NUMBER?' ON A TCASII ADVISORY. WE DSNDED TO FL213. AFTER THE TFC CONFLICT, WE CLBED BACK TO FL220 AND PROCEEDED ON COURSE. AT THIS POINT, I DO NOT KNOW WHAT COULD HAVE CAUSED THIS TFC PROBLEM AND TCASII RA. MY GUESS IS THAT THE OTHER ACR MAY HAVE BEEN CLRED ABOVE US WITH A HIGH RATE OR CLIMB OR CLRED TO FL210 WITH A HIGH RATE OF CLB. POSSIBLY WE WERE BOTH CLRED TO MAINTAIN FL220.

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.