Back taxi on runway due to insufficient runway length from intersection.

Attributes
ACN	300100
Time
Date	199503
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bos
State Reference	MA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : bos artcc : tncf
Operator	common carrier : air taxi
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 135
Flight Phase	climbout : takeoff
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 4400 flight time type : 300
ASRS Report	300100
Person 2
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While taxiing on taxiway north for takeoff on runway 22R, boston tower called us and asked if we could depart from taxiway N1. Our operations manual allows us to move our aircraft 600 ft down the runway prior to initiating the takeoff roll and a takeoff procedure is specified. We initially assumed that departure from N1 would be well within this 600 ft, and told tower we could do it. Upon closer examination of the airport diagram, we realized that taxiway N1 was more like 900 ft from the departing end of runway 22R. By now, we were on taxiway N1 and shortly thereafter cleared into position. In order to meet our 600 ft criteria, we had to back taxi to within 600 ft of the end. After doing so, we departed using the appropriate takeoff procedure. The departure was normal. These last second requests from tower can trip up a crew that has already completed its takeoff and performance calculations based on previous instructions. It would have been helpful to us if when tower made its requests to use N1 intersection the controller could have told us how much runway length we would be losing. This would have saved a last min scramble for information by the flight crew, the estimation of the 600 ft point and the resulting back taxi.

Original NASA ASRS Text

Title: BACK TAXI ON RWY DUE TO INSUFFICIENT RWY LENGTH FROM INTXN.

Narrative: WHILE TAXIING ON TXWY N FOR TKOF ON RWY 22R, BOSTON TWR CALLED US AND ASKED IF WE COULD DEPART FROM TXWY N1. OUR OPS MANUAL ALLOWS US TO MOVE OUR ACFT 600 FT DOWN THE RWY PRIOR TO INITIATING THE TKOF ROLL AND A TKOF PROC IS SPECIFIED. WE INITIALLY ASSUMED THAT DEP FROM N1 WOULD BE WELL WITHIN THIS 600 FT, AND TOLD TWR WE COULD DO IT. UPON CLOSER EXAMINATION OF THE ARPT DIAGRAM, WE REALIZED THAT TXWY N1 WAS MORE LIKE 900 FT FROM THE DEPARTING END OF RWY 22R. BY NOW, WE WERE ON TXWY N1 AND SHORTLY THEREAFTER CLRED INTO POS. IN ORDER TO MEET OUR 600 FT CRITERIA, WE HAD TO BACK TAXI TO WITHIN 600 FT OF THE END. AFTER DOING SO, WE DEPARTED USING THE APPROPRIATE TKOF PROC. THE DEP WAS NORMAL. THESE LAST SECOND REQUESTS FROM TWR CAN TRIP UP A CREW THAT HAS ALREADY COMPLETED ITS TKOF AND PERFORMANCE CALCULATIONS BASED ON PREVIOUS INSTRUCTIONS. IT WOULD HAVE BEEN HELPFUL TO US IF WHEN TWR MADE ITS REQUESTS TO USE N1 INTXN THE CTLR COULD HAVE TOLD US HOW MUCH RWY LENGTH WE WOULD BE LOSING. THIS WOULD HAVE SAVED A LAST MIN SCRAMBLE FOR INFO BY THE FLC, THE ESTIMATION OF THE 600 FT POINT AND THE RESULTING BACK TAXI.

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.