Medium Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Workload; Communication Breakdown; Confusion
ATC Issue All Types
Air Traffic Control Issued Advisory / Alert
Procedure; Human Factors; Airport
While on the CEDAR CREEK STAR; ATC assigned a speed of 300 KTS for traffic with a clearance to cross 'HOWDY' at 11;000 and 250 KTS. At approximately FL180 ATC vectored us off the arrival and; approximately 90 seconds later; cleared us back direct HOWDY. I instructed the First Officer to ask if ATC still wanted 300 KTS. ATC then said 'no comply with the speed restrictions on the arrival.' Approximately 10 seconds later the Controller asked if we were going to be able to make the restriction [at HOWDY]. Initially we responded yes; and then in the interest of passenger comfort and safety said no. The Controller then gave us a 40 degree vector off course and upon roll out re-cleared us back to HOWDY; descend and maintain 12;000 FT and to contact Approach. No altitudes or speed restrictions were violated; however this narrative is an example of what seems to be becoming commonplace on arrival. ATC is using speed and vectoring to obtain optimum spacing; once their spacing is optimized; the aircrew is then expected to make speed and altitude restrictions. While on the vector the aircrew has no idea how long the vector will be or if the duration of assigned airspeed. Trying to plan a reasonable and comfortable descent becomes almost impossible. This example is one of at least two on this pairing and two on my last four day trip. It appears to me that ATC is assigning high speeds and then relying on the crew to remind them that there is a speed restriction over the fix. Please advise DFW ATC that if they assign a speed and a vector they are responsible for insuring that THEY specify that the restrictions over a fix will still be expected. It's becoming common once a speed is assigned that the aircrew has to ask if the fix crossing restrictions are still in place....and then as an after thought 'yes comply with the speed and altitude restrictions' This phenomenon seems unique to DFW.
An air carrier Captain took exception to DFW TRACON's habit of assigning speeds for spacing and/or vectors off of STARs and failing to specify their expectation with respect to subsequent published airspeed/altitude constraints on the arrival when they are re-cleared to intercept and descend via the arrival.