Air carrier medium large transport fails to initiate descent when commanded by iah approach.

Attributes
ACN	202238
Time
Date	199202
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : hub airport : iah
State Reference	TX
Altitude	msl bound lower : 5000 msl bound upper : 6000
Environment
Flight Conditions	Mixed
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
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	other pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 80 flight time total : 6000 flight time type : 1000
ASRS Report	202238
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 160 flight time total : 2100 flight time type : 1800
ASRS Report	202304
Events
Anomaly	altitude deviation : undershoot conflict : airborne less severe non adherence : clearance other anomaly other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

First officer was the PF. I was assisting as captain, approach called traffic at 1-2 O'clock at 5000 MSL and 10 mi. We were level at 6000 MSL assigned. We could not visually see the traffic as we were in and out of clouds above an overcast. We did see the traffic depicted on our TCASII in the correct area. We so advised approach who, then cleared us to descend to 5000 MSL and also cleared our traffic to climb from 5000 to 7000 MSL. We were concerned about descending into this climbing traffic and so we delayed our descent. Due to radio traffic we could not advise approach of this. After about 15 seconds the controller asked us if we had started our descent. We answered back that we were now starting the descent. Controller quickly gave us a vector 90 degrees to the left to avoid the traffic. Several other vectors were given to increase separation. During this time first officer allowed our speed to slow from 250 KTS to 210 KTS anticipating a turn toward final approach. Approach then asked our speed and not to slow before he requested it. We did not receive a RA from our TCASII -- to this traffic. Subsequent conversation with the controller after landing indicated we cleared the traffic laterally by 3 1/2 NM and no conflict occurred. However, we think the controller estimated there was adequate separation to descend us to 5000 while climbing our head-on traffic to 7000 MSL. We think the controller should have alerted us to what plan he had in mind. His vectors around this traffic did solve the separation problem, but left us in the dark as to what his plan was. It is possible that we could have received a TA if we had started our descent promptly to 5000. With the head-on traffic. The controller later said he was concerned that we had received a TCASII alert and were staying level to satisfy the TCASII command. I advised him we did not receive an alert. The supervisor contacted me and the matter was resolved with no action planned by ATC. Supplemental information from acn 202304. I did not hear ATC clear us to 5000 ft nor did I hear captain read back 5000 ft -- but it was set in altitude alert. Our SOP requires PF to state all cleared altitudes.

Original NASA ASRS Text

Title: ACR MLG FAILS TO INITIATE DSCNT WHEN COMMANDED BY IAH APCH.

Narrative: FO WAS THE PF. I WAS ASSISTING AS CAPT, APCH CALLED TFC AT 1-2 O'CLOCK AT 5000 MSL AND 10 MI. WE WERE LEVEL AT 6000 MSL ASSIGNED. WE COULD NOT VISUALLY SEE THE TFC AS WE WERE IN AND OUT OF CLOUDS ABOVE AN OVCST. WE DID SEE THE TFC DEPICTED ON OUR TCASII IN THE CORRECT AREA. WE SO ADVISED APCH WHO, THEN CLRED US TO DSND TO 5000 MSL AND ALSO CLRED OUR TFC TO CLB FROM 5000 TO 7000 MSL. WE WERE CONCERNED ABOUT DSNDING INTO THIS CLBING TFC AND SO WE DELAYED OUR DSCNT. DUE TO RADIO TFC WE COULD NOT ADVISE APCH OF THIS. AFTER ABOUT 15 SECONDS THE CTLR ASKED US IF WE HAD STARTED OUR DSCNT. WE ANSWERED BACK THAT WE WERE NOW STARTING THE DSCNT. CTLR QUICKLY GAVE US A VECTOR 90 DEGS TO THE L TO AVOID THE TFC. SEVERAL OTHER VECTORS WERE GIVEN TO INCREASE SEPARATION. DURING THIS TIME FO ALLOWED OUR SPD TO SLOW FROM 250 KTS TO 210 KTS ANTICIPATING A TURN TOWARD FINAL APCH. APCH THEN ASKED OUR SPD AND NOT TO SLOW BEFORE HE REQUESTED IT. WE DID NOT RECEIVE A RA FROM OUR TCASII -- TO THIS TFC. SUBSEQUENT CONVERSATION WITH THE CTLR AFTER LNDG INDICATED WE CLRED THE TFC LATERALLY BY 3 1/2 NM AND NO CONFLICT OCCURRED. HOWEVER, WE THINK THE CTLR ESTIMATED THERE WAS ADEQUATE SEPARATION TO DSND US TO 5000 WHILE CLBING OUR HEAD-ON TFC TO 7000 MSL. WE THINK THE CTLR SHOULD HAVE ALERTED US TO WHAT PLAN HE HAD IN MIND. HIS VECTORS AROUND THIS TFC DID SOLVE THE SEPARATION PROBLEM, BUT LEFT US IN THE DARK AS TO WHAT HIS PLAN WAS. IT IS POSSIBLE THAT WE COULD HAVE RECEIVED A TA IF WE HAD STARTED OUR DSCNT PROMPTLY TO 5000. WITH THE HEAD-ON TFC. THE CTLR LATER SAID HE WAS CONCERNED THAT WE HAD RECEIVED A TCASII ALERT AND WERE STAYING LEVEL TO SATISFY THE TCASII COMMAND. I ADVISED HIM WE DID NOT RECEIVE AN ALERT. THE SUPVR CONTACTED ME AND THE MATTER WAS RESOLVED WITH NO ACTION PLANNED BY ATC. SUPPLEMENTAL INFO FROM ACN 202304. I DID NOT HEAR ATC CLR US TO 5000 FT NOR DID I HEAR CAPT READ BACK 5000 FT -- BUT IT WAS SET IN ALT ALERT. OUR SOP REQUIRES PF TO STATE ALL CLRED ALTS.

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.