Narrative:

We were cruising at FL370 when captain decided to leave the cockpit to use the restroom. At approximately this time, I heard ZDV discussing something about altitude with an air carrier. The air carrier Y crew talked about a loss of headwinds but the conversation was very 'matter of fact.' I donned my mask, and captain got up to leave the cockpit. As he stood to leave the cockpit, center called me and asked for a 20 degree turn, and for me to descend from FL370 to FL360. Again, there was no urgency indicated by the tone of the request, nor the terminology. As the captain was getting out of his seat, I did answer the center call. It took no longer for captain to get out of his seat than usual, and I initiated a turn on the autoplt, as he finished maneuvering past me. I then reset the altitude alerter. The flight was planned and flown at high speed cruise, and therefore we were within a few KTS of vmo. I reduced power on the engine to slow down before initiating a descent. Because there had been no mention of urgency, and because my captain had become a standing passenger, I made no attempt to do this quickly. I initiated the descent on the autoplt, using flight crew, (which would hold the current speed), and reduced power slightly more. ZDV said the initiation of our descent took approximately 1 min. If my understanding is correct, the center instrumentation does not show that we had left altitude, until we had changed 300 ft. Since I had reduced power and speed slowly to allow for a smooth change, and had intended for no more than a 1000 FPM change, I do not doubt their numbers at all. As I approached approximately 36550 ft the controller gave me a climb back to FL370, and I believe it was right then that he gave me direct to vhp. A short time later, the controller called the air carrier Y aircraft, and told them to contact ZDV when they landed. A short time after that, he contacted us and told us to call ZDV also. He apologized as he did so, and said something along the lines of, 'I can't say you have done anything wrong, but I don't see anything.' we called ZDV, upon landing. Although the ZDV supervisor said this would go no further, she indicated we might have helped out the other aircraft, had we initiated the descent quicker. If that is so, I can only say that I would only have changed the actions I took, if I had known the situation was different than what I was led to believe by the very matter of fact conversation between the air carrier Y and the center, and by the terminology given by the center. At some point, the center indicated that we came within 2.9 mi. We did not receive any TCASII alert of any type, and I saw nothing on our displays, however, I do not know or remember for sure what range they were set to.

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Original NASA ASRS Text

Title: HS25 IS SLOW IN RESPONDING TO DSCNT CLRNC FROM FL370 IN ZDV AIRSPACE.

Narrative: WE WERE CRUISING AT FL370 WHEN CAPT DECIDED TO LEAVE THE COCKPIT TO USE THE RESTROOM. AT APPROX THIS TIME, I HEARD ZDV DISCUSSING SOMETHING ABOUT ALT WITH AN ACR. THE ACR Y CREW TALKED ABOUT A LOSS OF HEADWINDS BUT THE CONVERSATION WAS VERY 'MATTER OF FACT.' I DONNED MY MASK, AND CAPT GOT UP TO LEAVE THE COCKPIT. AS HE STOOD TO LEAVE THE COCKPIT, CTR CALLED ME AND ASKED FOR A 20 DEG TURN, AND FOR ME TO DSND FROM FL370 TO FL360. AGAIN, THERE WAS NO URGENCY INDICATED BY THE TONE OF THE REQUEST, NOR THE TERMINOLOGY. AS THE CAPT WAS GETTING OUT OF HIS SEAT, I DID ANSWER THE CTR CALL. IT TOOK NO LONGER FOR CAPT TO GET OUT OF HIS SEAT THAN USUAL, AND I INITIATED A TURN ON THE AUTOPLT, AS HE FINISHED MANEUVERING PAST ME. I THEN RESET THE ALT ALERTER. THE FLT WAS PLANNED AND FLOWN AT HIGH SPD CRUISE, AND THEREFORE WE WERE WITHIN A FEW KTS OF VMO. I REDUCED PWR ON THE ENG TO SLOW DOWN BEFORE INITIATING A DSCNT. BECAUSE THERE HAD BEEN NO MENTION OF URGENCY, AND BECAUSE MY CAPT HAD BECOME A STANDING PAX, I MADE NO ATTEMPT TO DO THIS QUICKLY. I INITIATED THE DSCNT ON THE AUTOPLT, USING FLC, (WHICH WOULD HOLD THE CURRENT SPD), AND REDUCED PWR SLIGHTLY MORE. ZDV SAID THE INITIATION OF OUR DSCNT TOOK APPROX 1 MIN. IF MY UNDERSTANDING IS CORRECT, THE CTR INSTRUMENTATION DOES NOT SHOW THAT WE HAD LEFT ALT, UNTIL WE HAD CHANGED 300 FT. SINCE I HAD REDUCED PWR AND SPD SLOWLY TO ALLOW FOR A SMOOTH CHANGE, AND HAD INTENDED FOR NO MORE THAN A 1000 FPM CHANGE, I DO NOT DOUBT THEIR NUMBERS AT ALL. AS I APCHED APPROX 36550 FT THE CTLR GAVE ME A CLB BACK TO FL370, AND I BELIEVE IT WAS RIGHT THEN THAT HE GAVE ME DIRECT TO VHP. A SHORT TIME LATER, THE CTLR CALLED THE ACR Y ACFT, AND TOLD THEM TO CONTACT ZDV WHEN THEY LANDED. A SHORT TIME AFTER THAT, HE CONTACTED US AND TOLD US TO CALL ZDV ALSO. HE APOLOGIZED AS HE DID SO, AND SAID SOMETHING ALONG THE LINES OF, 'I CAN'T SAY YOU HAVE DONE ANYTHING WRONG, BUT I DON'T SEE ANYTHING.' WE CALLED ZDV, UPON LNDG. ALTHOUGH THE ZDV SUPVR SAID THIS WOULD GO NO FURTHER, SHE INDICATED WE MIGHT HAVE HELPED OUT THE OTHER ACFT, HAD WE INITIATED THE DSCNT QUICKER. IF THAT IS SO, I CAN ONLY SAY THAT I WOULD ONLY HAVE CHANGED THE ACTIONS I TOOK, IF I HAD KNOWN THE SIT WAS DIFFERENT THAN WHAT I WAS LED TO BELIEVE BY THE VERY MATTER OF FACT CONVERSATION BTWN THE ACR Y AND THE CTR, AND BY THE TERMINOLOGY GIVEN BY THE CTR. AT SOME POINT, THE CTR INDICATED THAT WE CAME WITHIN 2.9 MI. WE DID NOT RECEIVE ANY TCASII ALERT OF ANY TYPE, AND I SAW NOTHING ON OUR DISPLAYS, HOWEVER, I DO NOT KNOW OR REMEMBER FOR SURE WHAT RANGE THEY WERE SET TO.

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.