Narrative:

The incident occurred during an arrival push to iad from the northwest. Aircraft Y was given a descent clearance from FL260 to FL240 and came within less than standard separation from aircraft X at FL250. Several factors contributed to this incident, probably foremost was that there was no equipment malfunction at iah approach where they could not take automated handoffs at the northwest gate. Because they had to take manual handoffs, they required 20 mi in trail separation for all arrs. This caused the high sector to give the low sector at least 25 mi in trail. Because of this, aircraft were being vectored all over the sky. Additionally, there is a new STAR to iah from the northwest to iah which is very confusing to the pilots and almost all are asking for confirmation on the clearance. Additionally the new arrival requires aircraft to be at 10000 ft and 250 KTS 9 mi further out from the airport. This means the controller has to make sure the aircraft are started down sooner. All arrs from ZFW to this sector and from aus high to this sector now have a restr to be at FL290 or below. This puts many aircraft at the same altitude, with the extended in trail and the extensive vectoring required to achieve it. Having them all at the same altitude is not a good thing, because many times we have to vector aircraft toward one another. Also, the new system has erroneous information as to what is required and what is expected by the pilots.

Related reports:

Google
 

Original NASA ASRS Text

Title: ZHU CTLR EXPERIENCED LOSS OF SEPARATION WITH DSNDING AND ENRTE ACFT AT FL250.

Narrative: THE INCIDENT OCCURRED DURING AN ARR PUSH TO IAD FROM THE NW. ACFT Y WAS GIVEN A DSCNT CLRNC FROM FL260 TO FL240 AND CAME WITHIN LTSS FROM ACFT X AT FL250. SEVERAL FACTORS CONTRIBUTED TO THIS INCIDENT, PROBABLY FOREMOST WAS THAT THERE WAS NO EQUIP MALFUNCTION AT IAH APCH WHERE THEY COULD NOT TAKE AUTOMATED HDOFS AT THE NW GATE. BECAUSE THEY HAD TO TAKE MANUAL HDOFS, THEY REQUIRED 20 MI IN TRAIL SEPARATION FOR ALL ARRS. THIS CAUSED THE HIGH SECTOR TO GIVE THE LOW SECTOR AT LEAST 25 MI IN TRAIL. BECAUSE OF THIS, ACFT WERE BEING VECTORED ALL OVER THE SKY. ADDITIONALLY, THERE IS A NEW STAR TO IAH FROM THE NW TO IAH WHICH IS VERY CONFUSING TO THE PLTS AND ALMOST ALL ARE ASKING FOR CONFIRMATION ON THE CLRNC. ADDITIONALLY THE NEW ARR REQUIRES ACFT TO BE AT 10000 FT AND 250 KTS 9 MI FURTHER OUT FROM THE ARPT. THIS MEANS THE CTLR HAS TO MAKE SURE THE ACFT ARE STARTED DOWN SOONER. ALL ARRS FROM ZFW TO THIS SECTOR AND FROM AUS HIGH TO THIS SECTOR NOW HAVE A RESTR TO BE AT FL290 OR BELOW. THIS PUTS MANY ACFT AT THE SAME ALT, WITH THE EXTENDED IN TRAIL AND THE EXTENSIVE VECTORING REQUIRED TO ACHIEVE IT. HAVING THEM ALL AT THE SAME ALT IS NOT A GOOD THING, BECAUSE MANY TIMES WE HAVE TO VECTOR ACFT TOWARD ONE ANOTHER. ALSO, THE NEW SYS HAS ERRONEOUS INFO AS TO WHAT IS REQUIRED AND WHAT IS EXPECTED BY THE PLTS.

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.