Narrative:

Mission involved providing target aircraft for test of air search radar on board a vessel that had recently completed a major overhaul. Ship required target aircraft to be at 40000', fly overhead and proceed 225 NM southeast, do a 180 degree turn and return to overhead. PIC requested and received an IFR clearance from boston center to operate as requested in a block altitude from FL390 to FL410. As flight proceeded offshore at FL400, boston center advised that new york center would require FL410 due to traffic. After concurrence with ship radar operator that 1000' increase would not degrade tests, PIC accepted FL410. Boston center then handed flight off to new york with communications through commercial radio on 129.9. As flight approached designated turn point, I recognized that even though nearly full available power was being utilized, indicated airspeed was decreasing at a very slow rate. I advised copilot (PF) to make the turn at a very slow rate. As I preparted to ask for lower altitude and make a position report, I became somewhat distraction and cp selected heading mode on flight director. The autoplt placed aircraft in a 28 degree bank. Airspeed decreased further and at an alarming rate. I directed cp to level wings but pre stall buffet was felt by the entire crew. PF attempted to maintain FL410 but it became obvious that a stall would soon occur. I then directed a slow descent and advised commercial radio of problem. Ny center came up on commercial radio frequency and advised me to stay at FL410 due to traffic. I advised ny center that I was unable to maintain altitude due to impending stall. The aircraft continued descent at 500-1000 ft/min and leveled off at 38500' MSL. During descent, I turned on all landing lights and directed all crew members to maintain increased watch for traffic. None was sighted despite unlimited visibility. Ny center advised latitude/long position of two conflicting heavy jets at FL370 and 390 respectively then directed us to maintain FL380. This allowed us to increase airspeed as we were handed off to boston center. Boston then assigned FL390 for the remainder of the flight. I was clearly in error by accepting FL410. Once at that altitude, I realized that the aircraft was too heavy and that airspeed was slowly decreasing but failed to do anything about the situation. I also failed to listen to an unconsciously given hint given by my copilot, well in advance of the incident, when at 160 KTS IAS and 335 KTS TAS he asked, 'I wonder what stall sp is?' I thought that I could gently turn back toward the ship, be handed off to boston, re-establish radar contact and descend before the situation got 'out of control'. Clearly, I allowed my desires to accomplish the radar tests to overshadow good common sense. Who was I allowing to be the PIC? The ships radar operator? The my controller? I should have monitored the cp's actions more closely although I in no way blame him for the problems. Although less experienced in the aircraft, he flew the airplane at high altitude, in a nearly stalled condition, as well or better than I could.

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Original NASA ASRS Text

Title: MDT JET AT 41000' MSL WAS TOO HIGH FOR ACFT CAPABILITY. AIRSPEED DECAYED. ACFT BUFFET ENSUED. ACFT HAD TO DESCEND TO LOWER ALT FOR STABILITY. MAY HAVE DESCENDED THROUGH ALT OF TWO ACFT IN THE APPROX AREA.

Narrative: MISSION INVOLVED PROVIDING TARGET ACFT FOR TEST OF AIR SEARCH RADAR ON BOARD A VESSEL THAT HAD RECENTLY COMPLETED A MAJOR OVERHAUL. SHIP REQUIRED TARGET ACFT TO BE AT 40000', FLY OVERHEAD AND PROCEED 225 NM SE, DO A 180 DEG TURN AND RETURN TO OVERHEAD. PIC REQUESTED AND RECEIVED AN IFR CLRNC FROM BOSTON CTR TO OPERATE AS REQUESTED IN A BLOCK ALT FROM FL390 TO FL410. AS FLT PROCEEDED OFFSHORE AT FL400, BOSTON CTR ADVISED THAT NEW YORK CTR WOULD REQUIRE FL410 DUE TO TFC. AFTER CONCURRENCE WITH SHIP RADAR OPERATOR THAT 1000' INCREASE WOULD NOT DEGRADE TESTS, PIC ACCEPTED FL410. BOSTON CTR THEN HANDED FLT OFF TO NEW YORK WITH COMS THROUGH COMMERCIAL RADIO ON 129.9. AS FLT APCHED DESIGNATED TURN POINT, I RECOGNIZED THAT EVEN THOUGH NEARLY FULL AVAILABLE PWR WAS BEING UTILIZED, INDICATED AIRSPD WAS DECREASING AT A VERY SLOW RATE. I ADVISED COPLT (PF) TO MAKE THE TURN AT A VERY SLOW RATE. AS I PREPARTED TO ASK FOR LOWER ALT AND MAKE A POS RPT, I BECAME SOMEWHAT DISTR AND CP SELECTED HDG MODE ON FLT DIRECTOR. THE AUTOPLT PLACED ACFT IN A 28 DEG BANK. AIRSPD DECREASED FURTHER AND AT AN ALARMING RATE. I DIRECTED CP TO LEVEL WINGS BUT PRE STALL BUFFET WAS FELT BY THE ENTIRE CREW. PF ATTEMPTED TO MAINTAIN FL410 BUT IT BECAME OBVIOUS THAT A STALL WOULD SOON OCCUR. I THEN DIRECTED A SLOW DSNT AND ADVISED COMMERCIAL RADIO OF PROB. NY CTR CAME UP ON COMMERCIAL RADIO FREQ AND ADVISED ME TO STAY AT FL410 DUE TO TFC. I ADVISED NY CTR THAT I WAS UNABLE TO MAINTAIN ALT DUE TO IMPENDING STALL. THE ACFT CONTINUED DSNT AT 500-1000 FT/MIN AND LEVELED OFF AT 38500' MSL. DURING DSNT, I TURNED ON ALL LNDG LIGHTS AND DIRECTED ALL CREW MEMBERS TO MAINTAIN INCREASED WATCH FOR TFC. NONE WAS SIGHTED DESPITE UNLIMITED VISIBILITY. NY CTR ADVISED LAT/LONG POS OF TWO CONFLICTING HVY JETS AT FL370 AND 390 RESPECTIVELY THEN DIRECTED US TO MAINTAIN FL380. THIS ALLOWED US TO INCREASE AIRSPD AS WE WERE HANDED OFF TO BOSTON CTR. BOSTON THEN ASSIGNED FL390 FOR THE REMAINDER OF THE FLT. I WAS CLRLY IN ERROR BY ACCEPTING FL410. ONCE AT THAT ALT, I REALIZED THAT THE ACFT WAS TOO HVY AND THAT AIRSPD WAS SLOWLY DECREASING BUT FAILED TO DO ANYTHING ABOUT THE SITUATION. I ALSO FAILED TO LISTEN TO AN UNCONSCIOUSLY GIVEN HINT GIVEN BY MY COPLT, WELL IN ADVANCE OF THE INCIDENT, WHEN AT 160 KTS IAS AND 335 KTS TAS HE ASKED, 'I WONDER WHAT STALL SP IS?' I THOUGHT THAT I COULD GENTLY TURN BACK TOWARD THE SHIP, BE HANDED OFF TO BOSTON, RE-ESTABLISH RADAR CONTACT AND DSND BEFORE THE SITUATION GOT 'OUT OF CTL'. CLRLY, I ALLOWED MY DESIRES TO ACCOMPLISH THE RADAR TESTS TO OVERSHADOW GOOD COMMON SENSE. WHO WAS I ALLOWING TO BE THE PIC? THE SHIPS RADAR OPERATOR? THE MY CTLR? I SHOULD HAVE MONITORED THE CP'S ACTIONS MORE CLOSELY ALTHOUGH I IN NO WAY BLAME HIM FOR THE PROBS. ALTHOUGH LESS EXPERIENCED IN THE ACFT, HE FLEW THE AIRPLANE AT HIGH ALT, IN A NEARLY STALLED CONDITION, AS WELL OR BETTER THAN I COULD.

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.