Lax local controller questions B767 is reason for not departing when cleared after a B747 had just t...

Attributes
ACN	553765
Time
Date	200207
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lax.airport
State Reference	CA
Altitude	agl single value : 0
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tower : lax.tower
Operator	common carrier : air carrier
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Flight Phase	ground : position and hold
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tower : lax.tower
Operator	common carrier : air carrier
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : takeoff ground : takeoff roll
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : multi engine pilot : flight engineer
Experience	flight time last 90 days : 125 flight time total : 15000 flight time type : 4200
ASRS Report	553765
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	inflight encounter : wake turbulence non adherence : required legal separation non adherence : published procedure other anomaly other
Independent Detector	other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

In a long line-up for takeoff runway 24L, we were positioned behind a B747. The B747 was cleared for takeoff and we were asked to taxi into position and hold. Wind conditions: 250 degrees at 10 KTS. This causes concern for wake turbulence purposes. We taxied into position and held on the runway. For safety reasons, I timed the B747's rotation until we received our takeoff clearance -- it was 35 seconds! I told my first officer to refuse the takeoff clearance. Lax tower came back and asked, 'why did we cancel the clearance?' we explained 'insufficient wake turbulence separation!' the tower snapped back and said 'next time you should ask for more time and then replied that they (lax tower) gave adequate separation by distance criteria!' we held on the runway another 3 mins and the tower asked us if we were ready for takeoff. We said yes, and departed uneventfully encountering no wake turbulence from the B747 and arrived safely in slc.

Original NASA ASRS Text

Title: LAX LCL CTLR QUESTIONS B767 IS REASON FOR NOT DEPARTING WHEN CLRED AFTER A B747 HAD JUST TAKEN OFF.

Narrative: IN A LONG LINE-UP FOR TKOF RWY 24L, WE WERE POSITIONED BEHIND A B747. THE B747 WAS CLRED FOR TKOF AND WE WERE ASKED TO TAXI INTO POS AND HOLD. WIND CONDITIONS: 250 DEGS AT 10 KTS. THIS CAUSES CONCERN FOR WAKE TURB PURPOSES. WE TAXIED INTO POS AND HELD ON THE RWY. FOR SAFETY REASONS, I TIMED THE B747'S ROTATION UNTIL WE RECEIVED OUR TKOF CLRNC -- IT WAS 35 SECONDS! I TOLD MY FO TO REFUSE THE TKOF CLRNC. LAX TWR CAME BACK AND ASKED, 'WHY DID WE CANCEL THE CLRNC?' WE EXPLAINED 'INSUFFICIENT WAKE TURB SEPARATION!' THE TWR SNAPPED BACK AND SAID 'NEXT TIME YOU SHOULD ASK FOR MORE TIME AND THEN REPLIED THAT THEY (LAX TWR) GAVE ADEQUATE SEPARATION BY DISTANCE CRITERIA!' WE HELD ON THE RWY ANOTHER 3 MINS AND THE TWR ASKED US IF WE WERE READY FOR TKOF. WE SAID YES, AND DEPARTED UNEVENTFULLY ENCOUNTERING NO WAKE TURB FROM THE B747 AND ARRIVED SAFELY IN SLC.

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.

Lax local controller questions B767 is reason for not departing when cleared after a B747 had just taken off.