B737-800
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Human-Machine Interface; Workload; Time Pressure
ATC Issue All Types; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Requested ATC Assistance / Clarification
Procedure; Chart Or Publication; Human Factors
I am writing this [report] to publish what I think are unsafe procedures in use [when] utilizing the HAWKZ 2 RNAV Arrival landing north. [We were] cleared direct FOOTT Intersection after we were cleared to descend via the HAWKZ 2 landing north. We were approximately 2;200 FT above profile due to the direct route. Center then requested a speed increase to 300 KTS; followed later by a reduction to 250 KTS; frequency change to approach and we were requested to fly 210 KTS. We managed to get back on profile but I think that the airspeed change requests from Center and approach when we are below 18;000 FT require excessive heads down time and have the high potential for deviations. Normal landing followed.Called Approach when we got on the ground to find out why the large airspeed changes contrary to the published speeds on the arrival and I talked with the supervisor on duty and he said it was due to sequencing with arrivals from the south but also the Local Controller's issues with fitting us in with arrivals from other arrivals from other directions.
A B737-800 Captain; cleared ro descend via the HAWKZ RNAV STAR to SEA; reported excessive ATC intervention with route shortening direct routes and large scale variations in assigned airspeeds.