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ZAU reported that the lead aircraft in a series along the same route failed to accelerate to 310 KTS as requested 11 minutes earlier and consequently all three subsequent aircraft had to be slowed which decreased separation.
| Attributes | |
| ACN | 1149398 |
| Time | |
| Date | 201402 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZAU.ARTCC |
| State Reference | IL |
| Environment | |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | B737-800 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Flight Plan | IFR |
| Person 1 | |
| Function | Enroute |
| Qualification | Air Traffic Control Fully Certified |
| Experience | Air Traffic Control Radar 22 |
| Events | |
| Anomaly | Conflict Airborne Conflict Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Speed All Types |
Narrative:
The B737-800 checked on descending to FL250 with 4th line coordination of 310+ in the data block; since he was going to be first; I cleared him direct to prise as soon as I was able. A few minutes later I noticed that the second aircraft in line was catching him even though he was assigned a slower speed of 300 KTS. I asked lead B737-800 what his airspeed was and he said 290 KTS; I told him that he was supposed to be doing 310 plus KTS and to speed up. I had to slow second aircraft; to below our going over speed of 300 KTS; to 280 KTS to keep separation. I also had to slow another air carrier that was behind the second aircraft earlier than planned because of the speed reduction given to the second aircraft. I went back and listened to the recordings and found that the previous sector had given the lead aircraft the clearance to transition to 310 plus 11 minutes prior to me questioning him about his speed.I have reported this exact scenario twice before. The B737-800 created a dangerous situation by not doing the speed assigned by ATC; and also by not alerting us to that fact. He had 11 minutes to reach the speed and failed to do so. I would like the pilots to take ATC speed clearances seriously and communicate if there is a problem with reaching the assigned speed. Please press this issue with the pilot organizations and airlines. This problem occurs across all air carriers and needs to be addressed because it is dangerous to all involved.
Original NASA ASRS Text
Title: ZAU reported that the lead aircraft in a series along the same route failed to accelerate to 310 KTS as requested 11 minutes earlier and consequently all three subsequent aircraft had to be slowed which decreased separation.
Narrative: The B737-800 checked on descending to FL250 with 4th line coordination of 310+ in the data block; since he was going to be first; I cleared him direct to PRISE as soon as I was able. A few minutes later I noticed that the second aircraft in line was catching him even though he was assigned a slower speed of 300 KTS. I asked lead B737-800 what his airspeed was and he said 290 KTS; I told him that he was supposed to be doing 310 plus KTS and to speed up. I had to slow second aircraft; to below our going over speed of 300 KTS; to 280 KTS to keep separation. I also had to slow another air carrier that was behind the second aircraft earlier than planned because of the speed reduction given to the second aircraft. I went back and listened to the recordings and found that the previous sector had given the lead aircraft the clearance to transition to 310 plus 11 minutes prior to me questioning him about his speed.I have reported this exact scenario twice before. The B737-800 created a dangerous situation by not doing the speed assigned by ATC; and also by not alerting us to that fact. He had 11 minutes to reach the speed and failed to do so. I would like the pilots to take ATC speed clearances seriously and communicate if there is a problem with reaching the assigned speed. Please press this issue with the pilot organizations and airlines. This problem occurs across all air carriers and needs to be addressed because it is dangerous to all involved.
Data retrieved from NASA's ASRS site 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.