An small aircraft pilot swears that he was assigned the same altitude as another aircraft.

Attributes
ACN	251790
Time
Date	199309
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : lrp airport : mtn
State Reference	PA
Altitude	msl bound lower : 5000 msl bound upper : 6000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bwi
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	climbout : intermediate altitude cruise other cruise other
Route In Use	enroute : on vectors enroute airway : bwi
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 180 flight time total : 4950 flight time type : 700
ASRS Report	251790
Person 2
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

The departure clearance from martin state airport contained an initial climb altitude of 3000 ft, expect 7000 ft 10 mins after departure. After takeoff, mtn tower handed us off to bwi departure who turned us northbound and continued our climb to 5000 ft. I acknowledged the clearance and dialed the new altitude into the aircraft's 'poor man's altitude alerter' (an inexpensive item which installs on the face of the altimeter). Shortly afterward, I was switched to another bwi controller. I checked in as I normally do '...with you in the climb through XXXX for 5000 ft.' the controller acknowledged this and (almost apologetically) promised us higher in a few mi. As we continued the climb to 5000 ft, I heard the controller issue another aircraft an immediate turn and then instruct us to turn immediately and climb to 6000 ft. I complied instantly, sensing the urgency in his voice. A few moments later the controller questioned our assigned altitude as he expected us to level off at 4000 ft. The passenger in the right pilot seat, a pilot himself, was wearing a headset and monitoring communications and the flight's progress. He states that he heard us cleared to 5000 ft, my acknowledgement and observed me change the altitude bug on the altimeter to 5000 ft. I stated to the controller that I was sure the previous controller had cleared us to 5000 ft and his reply was 'no problem, we worked it out on this end.' the flight continued without further incident. I do not believe that I was at fault in this situation. Anyone, including myself, can make a mistake. In this case, however, I would have had to hear the wrong altitude from the first departure controller, dial it into the altimeter, and report that altitude to 2 controllers without either one (or the pilot seated next to me) catching the error. Possible, I suppose, but not very likely. In any case, I do not know any way in which I could have prevented this situation and am thankful that it did not become more serious.

Original NASA ASRS Text

Title: AN SMA PLT SWEARS THAT HE WAS ASSIGNED THE SAME ALT AS ANOTHER ACFT.

Narrative: THE DEP CLRNC FROM MARTIN STATE ARPT CONTAINED AN INITIAL CLB ALT OF 3000 FT, EXPECT 7000 FT 10 MINS AFTER DEP. AFTER TKOF, MTN TWR HANDED US OFF TO BWI DEP WHO TURNED US NBOUND AND CONTINUED OUR CLB TO 5000 FT. I ACKNOWLEDGED THE CLRNC AND DIALED THE NEW ALT INTO THE ACFT'S 'POOR MAN'S ALT ALERTER' (AN INEXPENSIVE ITEM WHICH INSTALLS ON THE FACE OF THE ALTIMETER). SHORTLY AFTERWARD, I WAS SWITCHED TO ANOTHER BWI CTLR. I CHKED IN AS I NORMALLY DO '...WITH YOU IN THE CLB THROUGH XXXX FOR 5000 FT.' THE CTLR ACKNOWLEDGED THIS AND (ALMOST APOLOGETICALLY) PROMISED US HIGHER IN A FEW MI. AS WE CONTINUED THE CLB TO 5000 FT, I HEARD THE CTLR ISSUE ANOTHER ACFT AN IMMEDIATE TURN AND THEN INSTRUCT US TO TURN IMMEDIATELY AND CLB TO 6000 FT. I COMPLIED INSTANTLY, SENSING THE URGENCY IN HIS VOICE. A FEW MOMENTS LATER THE CTLR QUESTIONED OUR ASSIGNED ALT AS HE EXPECTED US TO LEVEL OFF AT 4000 FT. THE PAX IN THE R PLT SEAT, A PLT HIMSELF, WAS WEARING A HEADSET AND MONITORING COMS AND THE FLT'S PROGRESS. HE STATES THAT HE HEARD US CLRED TO 5000 FT, MY ACKNOWLEDGEMENT AND OBSERVED ME CHANGE THE ALT BUG ON THE ALTIMETER TO 5000 FT. I STATED TO THE CTLR THAT I WAS SURE THE PREVIOUS CTLR HAD CLRED US TO 5000 FT AND HIS REPLY WAS 'NO PROB, WE WORKED IT OUT ON THIS END.' THE FLT CONTINUED WITHOUT FURTHER INCIDENT. I DO NOT BELIEVE THAT I WAS AT FAULT IN THIS SIT. ANYONE, INCLUDING MYSELF, CAN MAKE A MISTAKE. IN THIS CASE, HOWEVER, I WOULD HAVE HAD TO HEAR THE WRONG ALT FROM THE FIRST DEP CTLR, DIAL IT INTO THE ALTIMETER, AND RPT THAT ALT TO 2 CTLRS WITHOUT EITHER ONE (OR THE PLT SEATED NEXT TO ME) CATCHING THE ERROR. POSSIBLE, I SUPPOSE, BUT NOT VERY LIKELY. IN ANY CASE, I DO NOT KNOW ANY WAY IN WHICH I COULD HAVE PREVENTED THIS SIT AND AM THANKFUL THAT IT DID NOT BECOME MORE SERIOUS.

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.