Altitude deviation altitude excursion from assigned.

Attributes
ACN	252274
Time
Date	199309
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bdr
State Reference	CT
Altitude	msl bound lower : 1500 msl bound upper : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	Other
Function	observation : observer
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 20 flight time total : 3900 flight time type : 10
ASRS Report	252274
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew faa : investigated
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On sep/fri/93, about PM55 local time, I was flying safety pilot in small aircraft. New york controller gave PIC, under the hood and handling the radio communication, a descent to 2000 ft, heading 150 degrees. Shortly after a different voice but using standard terminology said, 'descend and maintain 1500 ft.' the pilot complied after reading it back. Shortly after the controller asked us what we were doing at 1500 ft when we should be at 2000 ft. I think in retrospect that we received an illegal transmission from the ground. About 35 mins after the incident I reported it to the new york facility. I don't think I mentioned that we were making a practice ILS 6 at bdr when the incident occurred. After the false radio transmission we deviated about 500 ft on our altitude and then climbed back to 2000 ft. I do not think that the controller heard the illegal transmission as it was probably too far from where the nearest ground antenna is located. Later, I was contacted at home by an FAA representative and gave all the details as to the exact location of event for him to follow-up in his van which is equipped to detect illegal xmissions on the ground.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION FROM ASSIGNED.

Narrative: ON SEP/FRI/93, ABOUT PM55 LCL TIME, I WAS FLYING SAFETY PLT IN SMA. NEW YORK CTLR GAVE PIC, UNDER THE HOOD AND HANDLING THE RADIO COM, A DSCNT TO 2000 FT, HDG 150 DEGS. SHORTLY AFTER A DIFFERENT VOICE BUT USING STANDARD TERMINOLOGY SAID, 'DSND AND MAINTAIN 1500 FT.' THE PLT COMPLIED AFTER READING IT BACK. SHORTLY AFTER THE CTLR ASKED US WHAT WE WERE DOING AT 1500 FT WHEN WE SHOULD BE AT 2000 FT. I THINK IN RETROSPECT THAT WE RECEIVED AN ILLEGAL XMISSION FROM THE GND. ABOUT 35 MINS AFTER THE INCIDENT I RPTED IT TO THE NEW YORK FACILITY. I DON'T THINK I MENTIONED THAT WE WERE MAKING A PRACTICE ILS 6 AT BDR WHEN THE INCIDENT OCCURRED. AFTER THE FALSE RADIO XMISSION WE DEVIATED ABOUT 500 FT ON OUR ALT AND THEN CLBED BACK TO 2000 FT. I DO NOT THINK THAT THE CTLR HEARD THE ILLEGAL XMISSION AS IT WAS PROBABLY TOO FAR FROM WHERE THE NEAREST GND ANTENNA IS LOCATED. LATER, I WAS CONTACTED AT HOME BY AN FAA REPRESENTATIVE AND GAVE ALL THE DETAILS AS TO THE EXACT LOCATION OF EVENT FOR HIM TO FOLLOW-UP IN HIS VAN WHICH IS EQUIPPED TO DETECT ILLEGAL XMISSIONS ON THE GND.

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.