Large Transport
Flight Crew Air Transport Pilot (ATP)
Confusion; Communication Breakdown; Situational Awareness; Workload
ATC Issue All Types; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Airport; Procedure
Our aircraft was on a dog leg to final with our traffic (b757) and field in sight. Approach instructed us to follow traffic; maintain 180 knots until the marker; and cleared us for a visual approach. At the time we were closing on our traffic and were in the process of gradually slowing to 180 knots. We closed to just outside of three miles on our traffic and then slowed to final approach speed to maintain adequate separation for wake turbulence. As we slowed below 180 knots (outside of the marker) I advised the Tower that we couldn't maintain assigned speed due to our traffic. He stated that slowing was not a problem and that we still had 30 knots of closure on our traffic. Landing was noneventful. During taxi-back Ground Control advised us that Approach would like to talk to us but he didn't believe there was an issue since everything appeared normal. We called and spoke with a Supervisor. I informed him that I was not about to let a Controller put us in a bad spot. We followed his instructions to the letter until we couldn't and then we advised Tower that we had to slow further. Supervisor told me that reduced separation on a (B757) is two and a half miles. I believe it is three miles. There was no violation here; but ATC needs to understand that on occasion; a clearance may not work out. I understand that Company has had some deviations at ATL; but from my perspective ATL Approach needs to get off their high horse.
An aircraft on a visual to ATL was requested to maintain 180 kts to the marker behind a heavier aircraft; but slowed in order to maintain 3 miles spacing behind the heavy. ATC objected and stated 2.5 miles is the new separation standard.