Narrative:

The flight had just departed san on a part 121 scheduled flight from san to bur. The flight had been assigned the pebble 2 departure which requires a 290 degree heading after departure and an altitude assignment of 8000 ft. The flight had climbed through approximately 1000 ft when the san tower told us to contact departure. We attempted to contact departure but were unable due to congestion on the frequency and the departure controller eventually contacted us. On initial contact the controller told us to slow immediately to 150 KTS, and I (as the PNF) asked the controller what type of aircraft we were following in hopes of acquiring the aircraft visually and provide our own separation. Again the controller advised us to slow the aircraft to 150 KTS, which the captain (the PF) was attempting to do. At this point in the flight, the aircraft was at approximately 200 KTS and climbing in excess of 2500-3000 FPM. When the controller saw that we were not slowing quickly enough, he asked us to stop our climb at 4000 ft. This occurred at approximately 4500-5000 ft. We attempted to inform the controller that we would be unable to comply with the new altitude assignment, but were unable to contact him due to congestion on the frequency and the captain kept the aircraft climbing to our original assigned altitude of 8000 ft. We were then vectored to the south to avoid conflicting traffic and eventually vectored on course towards our destination. Throughout the flight the captain had the conflicting aircraft in sight and would have been unable to comply with the new altitude and speed assignment for these reasons: 1) altitude -- the flight had already climbed through the newly assigned altitude by 1000 ft and the aircraft was climbing in excess of 2500 FPM and would have subjected the flight attendant (who was moving about the cabin) to possible injury if we attempted to make an immediate descent back to 4000 ft. 2) speed -- on initial contact the 150 KT speed restr would have been attainable by pitching the nose of the aircraft up and increasing the climb rate, but when the altitude restr was placed on us there was no way of obtaining both a descent back down to 4000 ft and speed of 150 KTS without retarding the throttles to flight idle, extending the landing gear and extending a minimum of 15 degrees of flaps, which is undesirable on departure climb out. There are also factors on the side of the controling agency which also may have contributed to this occurrence and these are only speculations on my part considering I do not have a working knowledge of the ATC system from a controller's point of view. 3) the controller's lack of basic knowledge of our aircraft performance and what we as a crew are capable of reasonably accomplishing with the aircraft. 4) coordination between the tower controllers at san and socal departure control by allowing a faster aircraft to depart so close behind a slower moving aircraft on the same departure SID. 5) frequency congestion or the inability to quickly convey our acceptance or denial of a particular clearance. The captain, upon reaching our destination, phoned socal approach control and spoke with the supervisor and both sides of the issue were discussed. The supervisor assured the captain that adequate separation was never compromised and that he would not pursue the matter any further.

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Original NASA ASRS Text

Title: E120 IN A CLOSE IN TRAIL SEPARATION FROM PRECEDING ACFT IN SID DEP PROC. AMENDED CLRNC ALT CHANGE AIRSPD ISSUED. FLC FAILS TO FOLLOW CLRNCS.

Narrative: THE FLT HAD JUST DEPARTED SAN ON A PART 121 SCHEDULED FLT FROM SAN TO BUR. THE FLT HAD BEEN ASSIGNED THE PEBBLE 2 DEP WHICH REQUIRES A 290 DEG HDG AFTER DEP AND AN ALT ASSIGNMENT OF 8000 FT. THE FLT HAD CLBED THROUGH APPROX 1000 FT WHEN THE SAN TWR TOLD US TO CONTACT DEP. WE ATTEMPTED TO CONTACT DEP BUT WERE UNABLE DUE TO CONGESTION ON THE FREQ AND THE DEP CTLR EVENTUALLY CONTACTED US. ON INITIAL CONTACT THE CTLR TOLD US TO SLOW IMMEDIATELY TO 150 KTS, AND I (AS THE PNF) ASKED THE CTLR WHAT TYPE OF ACFT WE WERE FOLLOWING IN HOPES OF ACQUIRING THE ACFT VISUALLY AND PROVIDE OUR OWN SEPARATION. AGAIN THE CTLR ADVISED US TO SLOW THE ACFT TO 150 KTS, WHICH THE CAPT (THE PF) WAS ATTEMPTING TO DO. AT THIS POINT IN THE FLT, THE ACFT WAS AT APPROX 200 KTS AND CLBING IN EXCESS OF 2500-3000 FPM. WHEN THE CTLR SAW THAT WE WERE NOT SLOWING QUICKLY ENOUGH, HE ASKED US TO STOP OUR CLB AT 4000 FT. THIS OCCURRED AT APPROX 4500-5000 FT. WE ATTEMPTED TO INFORM THE CTLR THAT WE WOULD BE UNABLE TO COMPLY WITH THE NEW ALT ASSIGNMENT, BUT WERE UNABLE TO CONTACT HIM DUE TO CONGESTION ON THE FREQ AND THE CAPT KEPT THE ACFT CLBING TO OUR ORIGINAL ASSIGNED ALT OF 8000 FT. WE WERE THEN VECTORED TO THE S TO AVOID CONFLICTING TFC AND EVENTUALLY VECTORED ON COURSE TOWARDS OUR DEST. THROUGHOUT THE FLT THE CAPT HAD THE CONFLICTING ACFT IN SIGHT AND WOULD HAVE BEEN UNABLE TO COMPLY WITH THE NEW ALT AND SPD ASSIGNMENT FOR THESE REASONS: 1) ALT -- THE FLT HAD ALREADY CLBED THROUGH THE NEWLY ASSIGNED ALT BY 1000 FT AND THE ACFT WAS CLBING IN EXCESS OF 2500 FPM AND WOULD HAVE SUBJECTED THE FLT ATTENDANT (WHO WAS MOVING ABOUT THE CABIN) TO POSSIBLE INJURY IF WE ATTEMPTED TO MAKE AN IMMEDIATE DSCNT BACK TO 4000 FT. 2) SPD -- ON INITIAL CONTACT THE 150 KT SPD RESTR WOULD HAVE BEEN ATTAINABLE BY PITCHING THE NOSE OF THE ACFT UP AND INCREASING THE CLB RATE, BUT WHEN THE ALT RESTR WAS PLACED ON US THERE WAS NO WAY OF OBTAINING BOTH A DSCNT BACK DOWN TO 4000 FT AND SPD OF 150 KTS WITHOUT RETARDING THE THROTTLES TO FLT IDLE, EXTENDING THE LNDG GEAR AND EXTENDING A MINIMUM OF 15 DEGS OF FLAPS, WHICH IS UNDESIRABLE ON DEP CLBOUT. THERE ARE ALSO FACTORS ON THE SIDE OF THE CTLING AGENCY WHICH ALSO MAY HAVE CONTRIBUTED TO THIS OCCURRENCE AND THESE ARE ONLY SPECULATIONS ON MY PART CONSIDERING I DO NOT HAVE A WORKING KNOWLEDGE OF THE ATC SYS FROM A CTLR'S POINT OF VIEW. 3) THE CTLR'S LACK OF BASIC KNOWLEDGE OF OUR ACFT PERFORMANCE AND WHAT WE AS A CREW ARE CAPABLE OF REASONABLY ACCOMPLISHING WITH THE ACFT. 4) COORD BTWN THE TWR CTLRS AT SAN AND SOCAL DEP CTL BY ALLOWING A FASTER ACFT TO DEPART SO CLOSE BEHIND A SLOWER MOVING ACFT ON THE SAME DEP SID. 5) FREQ CONGESTION OR THE INABILITY TO QUICKLY CONVEY OUR ACCEPTANCE OR DENIAL OF A PARTICULAR CLRNC. THE CAPT, UPON REACHING OUR DEST, PHONED SOCAL APCH CTL AND SPOKE WITH THE SUPVR AND BOTH SIDES OF THE ISSUE WERE DISCUSSED. THE SUPVR ASSURED THE CAPT THAT ADEQUATE SEPARATION WAS NEVER COMPROMISED AND THAT HE WOULD NOT PURSUE THE MATTER ANY FURTHER.

Data retrieved from NASA's ASRS site as of July 2007 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.