ARTCC controller and crew disagree on time element of a climb clearance.

Attributes
ACN	478445
Time
Date	200007
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zdv.artcc
State Reference	CO
Altitude	msl bound lower : 37000 msl bound upper : 41000
Environment
Flight Conditions	VMC
Weather Elements	Thunderstorm Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Route In Use	enroute other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : cfi pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 235 flight time total : 7700 flight time type : 1400
ASRS Report	478445
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

I was working as first officer and PNF on air carrier X flight from las-msp. We were level flight at FL370, deviating from our route around thunderstorms. We were experiencing light turbulence as we approached an area of WX that was giving light radar returns, surrounded by areas of heavy radar returns. FL370 was going to put us right where we judged the tops to be. The captain and I decided that we were able to climb and FL410 would keep us clear of the blow-off we were trying to avoid, in addition to providing a safe margin above the WX. I called ZDV and requested FL410. The radio conversation was as follows. Air carrier X: 'den, air carrier X request FL410.' denver: 'air carrier X, I will need you level by XA39Z, time now XA33Z. Can you make it by XA39?' (we were heavy and we knew it was going to be tight, but determined that we could make it in the allotted time.) air carrier X: 'affirmative.' denver: 'air carrier X, climb and maintain FL410.' air carrier X: 'air carrier X climb and maintain FL410.' denver: 'air carrier X say altitude.' air carrier X: 'leaving FL407 at this time.' denver: 'air carrier X, say time.' air carrier X: 'we show XA39 exactly.' denver: 'you didn't make it did you?' (no response.) denver: 'air carrier X, say altitude now.' air carrier X: 'air carrier X FL408.5.' denver: 'say time.' air carrier X: XA40Z.' (by XA40:15 we were level at FL410.) so this raises the question: did we need to be there at exactly XA30:00, or did we have all 59 seconds of XA39:59 to reach the assigned altitude? If the answer is yes, then shouldn't we be required to time hack the seconds as well? The captain and I both confirmed XA33 on our individual clocks, however, we did not note the seconds. It is entirely possibly that we (air carrier X versus ZDV) were as far as 59 seconds apart on our time hack. In the past, controllers would issue similar clrncs by giving an exact amount of time to reach the clearance limit. For example, they would say 6 mins. It is my experience that this type of clearance is far less ambiguous. We would simply start our clocks and simultaneously start the altitude change. There was no questioning whose clock to be accurate and no need for time hacks. 6 mins is 6 mins. In closing, if ZDV had asked us if we could level in 5 mins, we would not have accepted the clearance.

Original NASA ASRS Text

Title: ARTCC CTLR AND CREW DISAGREE ON TIME ELEMENT OF A CLB CLRNC.

Narrative: I WAS WORKING AS FO AND PNF ON ACR X FLT FROM LAS-MSP. WE WERE LEVEL FLT AT FL370, DEVIATING FROM OUR RTE AROUND TSTMS. WE WERE EXPERIENCING LIGHT TURB AS WE APCHED AN AREA OF WX THAT WAS GIVING LIGHT RADAR RETURNS, SURROUNDED BY AREAS OF HVY RADAR RETURNS. FL370 WAS GOING TO PUT US RIGHT WHERE WE JUDGED THE TOPS TO BE. THE CAPT AND I DECIDED THAT WE WERE ABLE TO CLB AND FL410 WOULD KEEP US CLR OF THE BLOW-OFF WE WERE TRYING TO AVOID, IN ADDITION TO PROVIDING A SAFE MARGIN ABOVE THE WX. I CALLED ZDV AND REQUESTED FL410. THE RADIO CONVERSATION WAS AS FOLLOWS. ACR X: 'DEN, ACR X REQUEST FL410.' DENVER: 'ACR X, I WILL NEED YOU LEVEL BY XA39Z, TIME NOW XA33Z. CAN YOU MAKE IT BY XA39?' (WE WERE HVY AND WE KNEW IT WAS GOING TO BE TIGHT, BUT DETERMINED THAT WE COULD MAKE IT IN THE ALLOTTED TIME.) ACR X: 'AFFIRMATIVE.' DENVER: 'ACR X, CLB AND MAINTAIN FL410.' ACR X: 'ACR X CLB AND MAINTAIN FL410.' DENVER: 'ACR X SAY ALT.' ACR X: 'LEAVING FL407 AT THIS TIME.' DENVER: 'ACR X, SAY TIME.' ACR X: 'WE SHOW XA39 EXACTLY.' DENVER: 'YOU DIDN'T MAKE IT DID YOU?' (NO RESPONSE.) DENVER: 'ACR X, SAY ALT NOW.' ACR X: 'ACR X FL408.5.' DENVER: 'SAY TIME.' ACR X: XA40Z.' (BY XA40:15 WE WERE LEVEL AT FL410.) SO THIS RAISES THE QUESTION: DID WE NEED TO BE THERE AT EXACTLY XA30:00, OR DID WE HAVE ALL 59 SECONDS OF XA39:59 TO REACH THE ASSIGNED ALT? IF THE ANSWER IS YES, THEN SHOULDN'T WE BE REQUIRED TO TIME HACK THE SECONDS AS WELL? THE CAPT AND I BOTH CONFIRMED XA33 ON OUR INDIVIDUAL CLOCKS, HOWEVER, WE DID NOT NOTE THE SECONDS. IT IS ENTIRELY POSSIBLY THAT WE (ACR X VERSUS ZDV) WERE AS FAR AS 59 SECONDS APART ON OUR TIME HACK. IN THE PAST, CTLRS WOULD ISSUE SIMILAR CLRNCS BY GIVING AN EXACT AMOUNT OF TIME TO REACH THE CLRNC LIMIT. FOR EXAMPLE, THEY WOULD SAY 6 MINS. IT IS MY EXPERIENCE THAT THIS TYPE OF CLRNC IS FAR LESS AMBIGUOUS. WE WOULD SIMPLY START OUR CLOCKS AND SIMULTANEOUSLY START THE ALT CHANGE. THERE WAS NO QUESTIONING WHOSE CLOCK TO BE ACCURATE AND NO NEED FOR TIME HACKS. 6 MINS IS 6 MINS. IN CLOSING, IF ZDV HAD ASKED US IF WE COULD LEVEL IN 5 MINS, WE WOULD NOT HAVE ACCEPTED THE CLRNC.

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.