Air carrier cleared to descend then told to level off when only 100' from newly assigned altitude. R...

Attributes
ACN	181616
Time
Date	199106
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : iah
State Reference	TX
Altitude	msl bound lower : 4000 msl bound upper : 5200
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iah
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : atp
Experience	flight time last 90 days : 100 flight time total : 2100 flight time type : 80
ASRS Report	181616
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 3500 vertical : 600
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

We were on a base leg to runway 26 at iah and in a descent to 4000'. At 5000-5100' the controller issued instructions to level off at 5000'. We were in the WX and as we were leveling at around 4800-4900' to climb back to 5000' we broke out of the WX, saw conflicting traffic and got the TCAS a/V RA indications for a pullup. The traffic was below us 600-800' at 11 O'clock in a left descending turn, head-on. I pulled up more abruptly to about 5200' and then descended back down to 5000' when clear of traffic. The iah controller was extremely busy and the airspace was saturated with landing traffic.

Original NASA ASRS Text

Title: ACR CLEARED TO DESCEND THEN TOLD TO LEVEL OFF WHEN ONLY 100' FROM NEWLY ASSIGNED ALT. RECEIVES TCASII RA.

Narrative: WE WERE ON A BASE LEG TO RWY 26 AT IAH AND IN A DSNT TO 4000'. AT 5000-5100' THE CTLR ISSUED INSTRUCTIONS TO LEVEL OFF AT 5000'. WE WERE IN THE WX AND AS WE WERE LEVELING AT AROUND 4800-4900' TO CLB BACK TO 5000' WE BROKE OUT OF THE WX, SAW CONFLICTING TFC AND GOT THE TCAS A/V RA INDICATIONS FOR A PULLUP. THE TFC WAS BELOW US 600-800' AT 11 O'CLOCK IN A LEFT DSNDING TURN, HEAD-ON. I PULLED UP MORE ABRUPTLY TO ABOUT 5200' AND THEN DSNDED BACK DOWN TO 5000' WHEN CLR OF TFC. THE IAH CTLR WAS EXTREMELY BUSY AND THE AIRSPACE WAS SATURATED WITH LNDG TFC.

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.

Air carrier cleared to descend then told to level off when only 100' from newly assigned altitude. Receives TCASII RA.