A C421C aircraft on departure and instructed to remain below class B airspace, the base of which is ...

Attributes
ACN	392584
Time
Date	199801
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : las airport : vgt
State Reference	NV
Altitude	msl bound lower : 4500 msl bound upper : 4700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : las
Operator	general aviation : corporate
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute : on vectors
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : private pilot : commercial pilot : instrument
Experience	flight time last 90 days : 100 flight time total : 7161 flight time type : 250
ASRS Report	392584
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : private pilot : instrument pilot : commercial
Experience	flight time last 90 days : 80 flight time total : 672 flight time type : 170
ASRS Report	392490
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

A C421C departed from north las vegas airport approximately XX10 local time under VMC conditions and was given a discrete transponder code for class C service to chino, ca, at 14500 ft. Departure instructions from north las vegas included 'fly heading of 220 degrees and maintain outside class B airspace.' following takeoff, we flew heading 220 degrees and climbed to an indicated altitude of 4500 ft MSL (the overlying airspace in the area has a floor of 4500 ft). After clearing the overlying class B airspace, we continued VFR climb and were xferred from north las vegas tower to las vegas approach control. Upon contacting las vegas approach, the approach controller informed us that we had entered class B airspace at 4700 ft (200 ft above the floor of the space in that area). The approach controller instructed us to phone the local TRACON supervisor and then provided us with a heading and cleared us to 14500 ft. It is possible that the 200 ft incursion into class B airspace occurred as a result of a +/-200 ft difference between our altimeter and its mode C. Alternatively, we may have resumed climb and 'clipped' the very edge of the class B airspace upon resuming climb out. This situation could be avoided by leveling off at a lower altitude while departing under the overlying class B until xferred from north las vegas tower to las vegas approach and resuming climb out only after well clear of the class B airspace or until clearance through class B airspace is received.

Original NASA ASRS Text

Title: A C421C ACFT ON DEP AND INSTRUCTED TO REMAIN BELOW CLASS B AIRSPACE, THE BASE OF WHICH IS 4500 FT. FLC EITHER HAD A MODE C ERROR OR STARTED CLB ABOVE 4500 FT TOO EARLY AND CLIPPED THE EDGE OF CLASS B.

Narrative: A C421C DEPARTED FROM NORTH LAS VEGAS ARPT APPROX XX10 LCL TIME UNDER VMC CONDITIONS AND WAS GIVEN A DISCRETE XPONDER CODE FOR CLASS C SVC TO CHINO, CA, AT 14500 FT. DEP INSTRUCTIONS FROM NORTH LAS VEGAS INCLUDED 'FLY HDG OF 220 DEGS AND MAINTAIN OUTSIDE CLASS B AIRSPACE.' FOLLOWING TKOF, WE FLEW HDG 220 DEGS AND CLBED TO AN INDICATED ALT OF 4500 FT MSL (THE OVERLYING AIRSPACE IN THE AREA HAS A FLOOR OF 4500 FT). AFTER CLRING THE OVERLYING CLASS B AIRSPACE, WE CONTINUED VFR CLB AND WERE XFERRED FROM NORTH LAS VEGAS TWR TO LAS VEGAS APCH CTL. UPON CONTACTING LAS VEGAS APCH, THE APCH CTLR INFORMED US THAT WE HAD ENTERED CLASS B AIRSPACE AT 4700 FT (200 FT ABOVE THE FLOOR OF THE SPACE IN THAT AREA). THE APCH CTLR INSTRUCTED US TO PHONE THE LCL TRACON SUPVR AND THEN PROVIDED US WITH A HEADING AND CLRED US TO 14500 FT. IT IS POSSIBLE THAT THE 200 FT INCURSION INTO CLASS B AIRSPACE OCCURRED AS A RESULT OF A +/-200 FT DIFFERENCE BTWN OUR ALTIMETER AND ITS MODE C. ALTERNATIVELY, WE MAY HAVE RESUMED CLB AND 'CLIPPED' THE VERY EDGE OF THE CLASS B AIRSPACE UPON RESUMING CLBOUT. THIS SIT COULD BE AVOIDED BY LEVELING OFF AT A LOWER ALT WHILE DEPARTING UNDER THE OVERLYING CLASS B UNTIL XFERRED FROM NORTH LAS VEGAS TWR TO LAS VEGAS APCH AND RESUMING CLBOUT ONLY AFTER WELL CLR OF THE CLASS B AIRSPACE OR UNTIL CLRNC THROUGH CLASS B AIRSPACE IS RECEIVED.

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.

A C421C aircraft on departure and instructed to remain below class B airspace, the base of which is 4500 ft. Flight crew either had a mode C error or started climb above 4500 ft too early and clipped the edge of class B.