Possible incursion of class D airspace.

Attributes
ACN	306142
Time
Date	199505
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : rnt
State Reference	WA
Altitude	msl bound lower : 1700 msl bound upper : 1700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : rnt
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
ASRS Report	306142
Person 2
Affiliation	Other
Function	observation : passenger
Qualification	pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 23 flight time total : 1000 flight time type : 15
ASRS Report	306150
Events
Anomaly	non adherence : far other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation
Situations
Airport	other physical facility

Narrative:

While sebound in cruise, I determined that I was clear of rnt class D airspace. I monitored rnt tower for traffic awareness. Radio traffic was for 2 helicopters inbound to rnt air traffic area. I acquired 1 at 1 mi and 50-100 ft lower northbound. Did not acquire wbound traffic at 1000 ft. Later, closer examination of terminal area charts determined I may have clipped the east boundary of the rnt class D airspace. The difficulty of exact determination arises from the lack of reliable ground landmarks in rising terrain (which hill is at the edge?) and range estimates from airport by slant angles are unreliable with varying terrain hts. Airspace boundaries especially VFR related) that match reliable ground landmarks would mitigate this uncertainty.

Original NASA ASRS Text

Title: POSSIBLE INCURSION OF CLASS D AIRSPACE.

Narrative: WHILE SEBOUND IN CRUISE, I DETERMINED THAT I WAS CLR OF RNT CLASS D AIRSPACE. I MONITORED RNT TWR FOR TFC AWARENESS. RADIO TFC WAS FOR 2 HELIS INBOUND TO RNT ATA. I ACQUIRED 1 AT 1 MI AND 50-100 FT LOWER NBOUND. DID NOT ACQUIRE WBOUND TFC AT 1000 FT. LATER, CLOSER EXAMINATION OF TERMINAL AREA CHARTS DETERMINED I MAY HAVE CLIPPED THE E BOUNDARY OF THE RNT CLASS D AIRSPACE. THE DIFFICULTY OF EXACT DETERMINATION ARISES FROM THE LACK OF RELIABLE GND LANDMARKS IN RISING TERRAIN (WHICH HILL IS AT THE EDGE?) AND RANGE ESTIMATES FROM ARPT BY SLANT ANGLES ARE UNRELIABLE WITH VARYING TERRAIN HTS. AIRSPACE BOUNDARIES ESPECIALLY VFR RELATED) THAT MATCH RELIABLE GND LANDMARKS WOULD MITIGATE THIS UNCERTAINTY.

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.