B737-800
Flight Crew Air Transport Pilot (ATP)
Workload; Communication Breakdown
ATC Issue All Types; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance
Procedure; Human Factors
While departing on an RNAV departure the Controller cleared us to climb and maintain 230. I queried him about the altitude restrictions on the departure to which he responded 'all restrictions are cancelled'. We then deleted all the restrictions in the FMC including the 230 KT speed restriction. He then had a problem with our speed and said that his clearance did not delete the speed just the altitude restrictions. That isn't what he stated though. He then seemed to be very confused about both our speed and altitude and gave us 'stop your climb' and 'climb and maintain 230' at the same time. The Center Controller stated 'I apologize for their errors' to us when we check on. The Controller should have stated only that the altitude restrictions were cancelled when I tried to confirm his intent.
We were departing on the TWIN FALLS ONE (TWF1) departure out of SLC; which has all the typical altitude and speed restrictions commonly associated with RNAV departures. One peculiarity however; was our PDC stated 'maintain 10;000' and on a separate line stated 'maintain 230 KTS'. These PDC requirements matched the TWF1 up to SHOLZ Intersection; after which the FMC maintains 230 KTS all the way to MOFER which changes the speed restriction to 250 KTS. To ensure we complied with the PDC speed requirement; we put 230 KTS into the climb page; both below and above 10;000. Note I have flown a lot of RNAV departures and I have never encountered one that keeps the speed so low all the way to FL230. This added a level of complexity and non-standard flight deck procedures thus increasing workload. I was the pilot flying and when the aircraft passed SHOLZ at 10;000 FT MSL; we were given the following climb instructions: 'Flight#; climb to FL230. You are relieved of all restrictions.' The pilot not flying confirmed the radio call ensuring we were relieved of all restrictions and then proceeded to go heads down to delete the numerous coded constraints built into the TWF1. The aircraft accelerated to normal speed and began the climb to FL230. At approximately 17;000 FT MSL; the Controller said; 'Flight#; say your airspeed.' The pilot not flying replied; 'Flight#; 280 KTS'. The Controller then replied 'Flight#; you were given 230 KTS.' The pilot not flying replied; 'Flight#; you said we were relieved of all restrictions.' The Controller then proceeded to give us multiple heading changes; altitude assignments followed by amended altitude assignments; and a speed assignment of 250 KTS. The workload increased dramatically as both of us tried to keep up with all the requests. We were handed off to Salt Lake Center and upon check in; the new Controller said; 'Flight#; I apologize for all their errors.'The PDC created a level of confusion placing altitude and speed restrictions on top of a published RNAV departure. At a minimum; it is unnecessary or redundant; at best it added a layer of complexity that increased the error potential. The PDC simply needed to assign the TWF1 and a climb altitude such as FL 230. By stating 'maintain 10;000' and 'maintain 230 KTS' the PDC nullifies the TWF1 departure procedure after SHOLZ.The Controller's phrase 'You are relieved of all restrictions' was obviously not true. We even called back to verify we understood what was said. ATC needs to get this one solved and decide on a common; standardized phraseology that works in conjunction with RNAV departures so that pilots and controllers have a unified understanding of expectations. In retrospect; I wish we had been more specific and said: 'Flight#; understand we are relieved of the 230 KT speed restriction as well as the numerous coded altitude restrictions on the TWF1?' I will be more specific from now on. On the other hand; why assign RNAV procedures if you are not going to allow pilots to fly them as published. It seems like ATC tends to apply conventional aircraft handling procedures into RNAV procedures by amending speeds; headings; and altitudes. If ATC feels a need to maintain that level of control of aircraft in their sector; then perhaps we should return to conventional departures and arrivals instead of RNAV? I can only assume that controller training was in progress by the apology from the Salt Lake Center Controller. If not; then the series of altitude; heading and speed assignments we received was really out of the ordinary and it took a tremendous effort on both our parts to ensure compliance; however we were able to do what was requested.
B737-800 flight crew reports being cleared via the TWF1 departure from SLC with an added speed restriction of 230 KTS. Passing SHOLZ at 10;000 FT the crew is issued an unrestricted climb to FL230. Passing 17;000 FT the crew is admonished for exceeding 230 KTS.