Private pilot of a C172 failed to follow the track distance from the runway on a VFR departure proce...

Attributes
ACN	401130
Time
Date	199804
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bfi
State Reference	WA
Altitude	msl bound lower : 800 msl bound upper : 1000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : bfi tower : aus
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude climbout : takeoff
Route In Use	departure other
Flight Plan	VFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 20 flight time total : 195 flight time type : 170
ASRS Report	401130
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

I was departing boeing field for a destination southeast with winds from the north. There is a departure procedure, 'valley departure,' which allows pilots to 'squirt' through seatac class B and rnt class D without going into those areas. It's more common on takeoffs to the south because one maintains runway heading, then follows railroad tracks out. When winds are from the north, pilots stay to the side of the tracks, depending upon the runway. I departed runway 31R then was advised to maintain a 'close right downwind.' I've always interpreted this as 1/2 mi or less from the runway at pattern altitude (1000 ft for short runway 31R, 800 ft for the longer runway 31L), but the controller advised otherwise. Her use of the terminology meant 1-2 mi, and she was complaining when I'd follow the original less than or equal to 1/2 mi abeam. I'd suggest that we use specific distances to avoid ambiguity, especially in cases where it appears there's disagreement. Causal factors: I usually use runway 31L or runway 13R, the valley departure is not widely used since it involves maneuvering through a lot of weird airspace. I had done the departure only once before, the day earlier with an instructor.

Original NASA ASRS Text

Title: PVT PLT OF A C172 FAILED TO FOLLOW THE TRACK DISTANCE FROM THE RWY ON A VFR DEP PROC THAT THE TWR CTLR BELIEVED TO BE THE CORRECT DISTANCE.

Narrative: I WAS DEPARTING BOEING FIELD FOR A DEST SE WITH WINDS FROM THE N. THERE IS A DEP PROC, 'VALLEY DEP,' WHICH ALLOWS PLTS TO 'SQUIRT' THROUGH SEATAC CLASS B AND RNT CLASS D WITHOUT GOING INTO THOSE AREAS. IT'S MORE COMMON ON TKOFS TO THE S BECAUSE ONE MAINTAINS RWY HEADING, THEN FOLLOWS RAILROAD TRACKS OUT. WHEN WINDS ARE FROM THE N, PLTS STAY TO THE SIDE OF THE TRACKS, DEPENDING UPON THE RWY. I DEPARTED RWY 31R THEN WAS ADVISED TO MAINTAIN A 'CLOSE R DOWNWIND.' I'VE ALWAYS INTERPRETED THIS AS 1/2 MI OR LESS FROM THE RWY AT PATTERN ALT (1000 FT FOR SHORT RWY 31R, 800 FT FOR THE LONGER RWY 31L), BUT THE CTLR ADVISED OTHERWISE. HER USE OF THE TERMINOLOGY MEANT 1-2 MI, AND SHE WAS COMPLAINING WHEN I'D FOLLOW THE ORIGINAL LESS THAN OR EQUAL TO 1/2 MI ABEAM. I'D SUGGEST THAT WE USE SPECIFIC DISTANCES TO AVOID AMBIGUITY, ESPECIALLY IN CASES WHERE IT APPEARS THERE'S DISAGREEMENT. CAUSAL FACTORS: I USUALLY USE RWY 31L OR RWY 13R, THE VALLEY DEP IS NOT WIDELY USED SINCE IT INVOLVES MANEUVERING THROUGH A LOT OF WEIRD AIRSPACE. I HAD DONE THE DEP ONLY ONCE BEFORE, THE DAY EARLIER WITH AN INSTRUCTOR.

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.

Private pilot of a C172 failed to follow the track distance from the runway on a VFR departure procedure that the tower controller believed to be the correct distance.