ZJX controller described a loss of separation event at the boundary between enroute and terminal whe...

Narrative:

I was training on the radar as a cpc-it. I had 4 aircraft handed off to me with minimal separation and had to space them for arrival to mco. An A321 was leading the group and was assigned 300 KTS until reaching lamma where they needed to slow to 250 KTS. A B737 was the next aircraft and was initially assigned 280 KTS and a 20 degree right turn for spacing. I then issued the B737 a 140 heading because the aircraft was getting too close to an adjacent sector. I then issued the B737 a clearance direct lamma and maintain 300 KTS once I had about 7 miles because of following traffic 7 miles behind the B737. I then handed off the A321 and transferred communication to mco approach (F11). At that time; the B737 had an overtake of about 20 KTS. The next few radar hits showed speed differences of 30; 50; and then 70 KTS creating a bad overtake situation. I think it is possible that the radar was not giving accurate; or up to date; ground speeds or that mco approach slowed the A321. Mco approach was in communication with both aircraft at the time of incident. I believe it would be helpful to have a separation requirement of 3 miles entering the terminal environment from the enroute. In this case; the radar was less than 40 miles from the incident.

Original NASA ASRS Text

Title: ZJX Controller described a loss of separation event at the boundary between enroute and terminal when the leading aircraft apparently slowed below assigned speeds; the reporter recommending a transition area between centers and terminals allowing for reduced separation standards.

Narrative: I was training on the RADAR as a CPC-IT. I had 4 aircraft handed off to me with minimal separation and had to space them for arrival to MCO. An A321 was leading the group and was assigned 300 KTS until reaching LAMMA where they needed to slow to 250 KTS. A B737 was the next aircraft and was initially assigned 280 KTS and a 20 degree right turn for spacing. I then issued the B737 a 140 heading because the aircraft was getting too close to an adjacent sector. I then issued the B737 a clearance direct LAMMA and maintain 300 KTS once I had about 7 miles because of following traffic 7 miles behind the B737. I then handed off the A321 and transferred communication to MCO Approach (F11). At that time; the B737 had an overtake of about 20 KTS. The next few RADAR hits showed speed differences of 30; 50; and then 70 KTS creating a bad overtake situation. I think it is possible that the RADAR was not giving accurate; or up to date; ground speeds or that MCO Approach slowed the A321. MCO Approach was in communication with both aircraft at the time of incident. I believe it would be helpful to have a separation requirement of 3 miles entering the terminal environment from the enroute. In this case; the RADAR was less than 40 miles from the incident.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	989236
Time
Date	201201
Local Time Of Day	1201-1800
Place
Locale Reference	ZJX.ARTCC
State Reference	FL
Aircraft 1
Make Model Name	A321
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Aircraft 2
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Enroute Trainee
Qualification	Air Traffic Control Developmental
Person 2
Function	Enroute Instructor
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy

ZJX controller described a loss of separation event at the boundary between enroute and terminal when the leading aircraft apparently slowed below assigned speeds; the reporter recommending a transition area between centers and terminals allowing for reduced separation standards.