Misread STAR procedure and started turn early.

Attributes
ACN	162628
Time
Date	199011
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : gdm airport : bos
State Reference	MA
Altitude	msl bound lower : 8000 msl bound upper : 8000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Route In Use	arrival star : star enroute airway : v431
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 9000 flight time type : 4000
ASRS Report	162628
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were on the gardner two arrival into boston. Flying outbnd on V431 we had a crossing at bronc intersection and a frequency change from boston center to boston approach. Fairly busy on boston approach I asked the captain what heading we would fly and he asked boston approach and the reply was fly the arwy. I had misread the chart for the DME to rever intersection. I looked at the DME distance of 29 and thought it was 29 DME to rever from the gardner VOR when it was 49 DME to rever from gardner; I started the turn to the boston VOR with the 30 degree right of the boston VOR tuned into my VOR. The right was not coming in and I asked the captain about it and he looked at his chart for the gardner two arrival and said it is 49 DME to rever. I had already started to turn back to my previous heading (110 degree) that I was on before I made the turn and just after the captain said it was 49 DME. Boston approach called and said fly a heading of 090 degree. I believe the problem was caused by misreading the DME distance from the gardner VOR to rever intersection, it is easy to misread the distance because the two intxns of bronc and lobby are well defined leading on to believe rever is as well defined when it is not you have two intxns defined with the 15 direct course for bronc and lobby direct course 20 and if you are busy and just glance at the 29 you think 29 DME from gardner to rever. The rever intersection should be defined with a 49 DME or direct course 49.

Original NASA ASRS Text

Title: MISREAD STAR PROC AND STARTED TURN EARLY.

Narrative: WE WERE ON THE GARDNER TWO ARR INTO BOSTON. FLYING OUTBND ON V431 WE HAD A XING AT BRONC INTXN AND A FREQ CHANGE FROM BOSTON CTR TO BOSTON APCH. FAIRLY BUSY ON BOSTON APCH I ASKED THE CAPT WHAT HDG WE WOULD FLY AND HE ASKED BOSTON APCH AND THE REPLY WAS FLY THE ARWY. I HAD MISREAD THE CHART FOR THE DME TO REVER INTXN. I LOOKED AT THE DME DISTANCE OF 29 AND THOUGHT IT WAS 29 DME TO REVER FROM THE GARDNER VOR WHEN IT WAS 49 DME TO REVER FROM GARDNER; I STARTED THE TURN TO THE BOSTON VOR WITH THE 30 DEG R OF THE BOSTON VOR TUNED INTO MY VOR. THE R WAS NOT COMING IN AND I ASKED THE CAPT ABOUT IT AND HE LOOKED AT HIS CHART FOR THE GARDNER TWO ARR AND SAID IT IS 49 DME TO REVER. I HAD ALREADY STARTED TO TURN BACK TO MY PREVIOUS HDG (110 DEG) THAT I WAS ON BEFORE I MADE THE TURN AND JUST AFTER THE CAPT SAID IT WAS 49 DME. BOSTON APCH CALLED AND SAID FLY A HDG OF 090 DEG. I BELIEVE THE PROB WAS CAUSED BY MISREADING THE DME DISTANCE FROM THE GARDNER VOR TO REVER INTXN, IT IS EASY TO MISREAD THE DISTANCE BECAUSE THE TWO INTXNS OF BRONC AND LOBBY ARE WELL DEFINED LEADING ON TO BELIEVE REVER IS AS WELL DEFINED WHEN IT IS NOT YOU HAVE TWO INTXNS DEFINED WITH THE 15 DIRECT COURSE FOR BRONC AND LOBBY DIRECT COURSE 20 AND IF YOU ARE BUSY AND JUST GLANCE AT THE 29 YOU THINK 29 DME FROM GARDNER TO REVER. THE REVER INTXN SHOULD BE DEFINED WITH A 49 DME OR DIRECT COURSE 49.

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.