Narrative:

A management pilot/check airman/IOE instructor was the assigned captain and chose to fly from the right seat. Approximately 20 mins after takeoff from fyv; the aircraft was within 2000 ft of the planned and assigned cruise attitude. The captain asked if the altitude pre-select function worked on the autoplt. I responded yes; but not at slow indicated airspds as the aircraft would porpoise during leveloff. When 500 ft below the target altitude; I made visual contact with an approaching aircraft that had been displayed on the tcad for several mi. I called the traffic out to the captain and mentioned that tcad data indicated that this aircraft would be only +1000 ft above us at our assigned cruising altitude. I again cautioned the captain that our aircraft cold not smoothly level off when flying at this altitude and at a slow indicated airspeed. When the altitude preselect captured; the speed was between 210-215 KIAS. Initially; the aircraft's nose lowered for the leveloff; immediately began to sink and then began to porpoise in an attempt to hold the target altitude. After 4 or 5 porpoise cycles; the captain began hand flying the aircraft. The pitch attitude was changing between -1 degree and +8 degrees. I asked the captain if he wanted me to take the aircraft controls (the approaching aircraft was now less than 1 mi and its path would have it passing off of our right wing by more than 1/4 mi; but less than 3/4 mi). The captain declined. We continued to oscillate between -200 ft and +300 ft from our cruise altitude for approximately 1 1/2 mins. Within 10 seconds of the other aircraft passing us; that crew asked ATC; 'was the falcon we just passed rvsm'ed...?' ATC paused; and then said affirmative. That crew stated that 'we received both a TA and an RA from that falcon.'

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Original NASA ASRS Text

Title: ON REACHING CRUISING ALT IN 'DRVSM' AIRSPACE; FA20 PORPOISES DURING ALT CAPTURE MODE ON AUTOPLT. RESULTS IN LOSS OF SEPARATION AND TCASII TA AND RA ALERTS ON OPPOSITE DIRECTION ACFT.

Narrative: A MGMNT PLT/CHK AIRMAN/IOE INSTRUCTOR WAS THE ASSIGNED CAPT AND CHOSE TO FLY FROM THE R SEAT. APPROX 20 MINS AFTER TKOF FROM FYV; THE ACFT WAS WITHIN 2000 FT OF THE PLANNED AND ASSIGNED CRUISE ATTITUDE. THE CAPT ASKED IF THE ALT PRE-SELECT FUNCTION WORKED ON THE AUTOPLT. I RESPONDED YES; BUT NOT AT SLOW INDICATED AIRSPDS AS THE ACFT WOULD PORPOISE DURING LEVELOFF. WHEN 500 FT BELOW THE TARGET ALT; I MADE VISUAL CONTACT WITH AN APCHING ACFT THAT HAD BEEN DISPLAYED ON THE TCAD FOR SEVERAL MI. I CALLED THE TFC OUT TO THE CAPT AND MENTIONED THAT TCAD DATA INDICATED THAT THIS ACFT WOULD BE ONLY +1000 FT ABOVE US AT OUR ASSIGNED CRUISING ALT. I AGAIN CAUTIONED THE CAPT THAT OUR ACFT COLD NOT SMOOTHLY LEVEL OFF WHEN FLYING AT THIS ALT AND AT A SLOW INDICATED AIRSPD. WHEN THE ALT PRESELECT CAPTURED; THE SPD WAS BTWN 210-215 KIAS. INITIALLY; THE ACFT'S NOSE LOWERED FOR THE LEVELOFF; IMMEDIATELY BEGAN TO SINK AND THEN BEGAN TO PORPOISE IN AN ATTEMPT TO HOLD THE TARGET ALT. AFTER 4 OR 5 PORPOISE CYCLES; THE CAPT BEGAN HAND FLYING THE ACFT. THE PITCH ATTITUDE WAS CHANGING BTWN -1 DEG AND +8 DEGS. I ASKED THE CAPT IF HE WANTED ME TO TAKE THE ACFT CTLS (THE APCHING ACFT WAS NOW LESS THAN 1 MI AND ITS PATH WOULD HAVE IT PASSING OFF OF OUR R WING BY MORE THAN 1/4 MI; BUT LESS THAN 3/4 MI). THE CAPT DECLINED. WE CONTINUED TO OSCILLATE BTWN -200 FT AND +300 FT FROM OUR CRUISE ALT FOR APPROX 1 1/2 MINS. WITHIN 10 SECONDS OF THE OTHER ACFT PASSING US; THAT CREW ASKED ATC; 'WAS THE FALCON WE JUST PASSED RVSM'ED...?' ATC PAUSED; AND THEN SAID AFFIRMATIVE. THAT CREW STATED THAT 'WE RECEIVED BOTH A TA AND AN RA FROM THAT FALCON.'

Data retrieved from NASA's ASRS site as of January 2009 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.