Narrative:

It was a routine flight from roc to dca. Following ATC's directives, the first officer (PF) descended the aircraft towards the assigned altitude of 10000' MSL. About 15 mi north of baltimore VOR and just prior to leveling at that altitude the jump seat pilot noticed traffic converging (and apparently climbing) from the 11 O'clock position and promptly alerted the captain and first officer of the impending conflict. Immediately upon recognition of the situation both pilots simultaneously took the evasive actions of pulling back on the control column to stop the descent and turning the aircraft to the right to avoid a tip-tanked, twin-engine type aircraft. At the same time the pilot of the light twin appeared to dive away to its right. After the other aircraft (an small transport) passed off to the left, the captain questioned the controller if there had been any indication of the other aircraft on his radar screen. Initially, the controller responded that there was not, but seconds later confirmed another target at 10300'. The flight continued to dca normally thereafter. See and avoid--3 words all pilots (and their passenger) can live by. It really is essential and it works. The main question in this situation is why ATC did not detect the conflict and alert the flight before the need for evasive maneuvering. Computer glitch? Controller workload? Contributing factors (besides no radar controller callout of traffic which he apparently did not detect): the light twin seemed to be climbing directly into hazy sunshine which makes for very poor forward visibility for him. The medium large transport was leveling off from descent and at relatively low airspeed (clean confign and decelerating to 250 KTS). This puts it nose high making it more difficult to detect traffic ahead of and below the nose. To prevent recurrence: eliminate radar faultiness, continue seeing and avoiding, decrease controller workload.

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Original NASA ASRS Text

Title: NMAC.

Narrative: IT WAS A ROUTINE FLT FROM ROC TO DCA. FOLLOWING ATC'S DIRECTIVES, THE F/O (PF) DSNDED THE ACFT TOWARDS THE ASSIGNED ALT OF 10000' MSL. ABOUT 15 MI N OF BALTIMORE VOR AND JUST PRIOR TO LEVELING AT THAT ALT THE JUMP SEAT PLT NOTICED TFC CONVERGING (AND APPARENTLY CLBING) FROM THE 11 O'CLOCK POS AND PROMPTLY ALERTED THE CAPT AND F/O OF THE IMPENDING CONFLICT. IMMEDIATELY UPON RECOGNITION OF THE SITUATION BOTH PLTS SIMULTANEOUSLY TOOK THE EVASIVE ACTIONS OF PULLING BACK ON THE CONTROL COLUMN TO STOP THE DSCNT AND TURNING THE ACFT TO THE RIGHT TO AVOID A TIP-TANKED, TWIN-ENG TYPE ACFT. AT THE SAME TIME THE PLT OF THE LIGHT TWIN APPEARED TO DIVE AWAY TO ITS RIGHT. AFTER THE OTHER ACFT (AN SMT) PASSED OFF TO THE LEFT, THE CAPT QUESTIONED THE CTLR IF THERE HAD BEEN ANY INDICATION OF THE OTHER ACFT ON HIS RADAR SCREEN. INITIALLY, THE CTLR RESPONDED THAT THERE WAS NOT, BUT SECS LATER CONFIRMED ANOTHER TARGET AT 10300'. THE FLT CONTINUED TO DCA NORMALLY THEREAFTER. SEE AND AVOID--3 WORDS ALL PLTS (AND THEIR PAX) CAN LIVE BY. IT REALLY IS ESSENTIAL AND IT WORKS. THE MAIN QUESTION IN THIS SITUATION IS WHY ATC DID NOT DETECT THE CONFLICT AND ALERT THE FLT BEFORE THE NEED FOR EVASIVE MANEUVERING. COMPUTER GLITCH? CTLR WORKLOAD? CONTRIBUTING FACTORS (BESIDES NO RADAR CTLR CALLOUT OF TFC WHICH HE APPARENTLY DID NOT DETECT): THE LIGHT TWIN SEEMED TO BE CLBING DIRECTLY INTO HAZY SUNSHINE WHICH MAKES FOR VERY POOR FORWARD VIS FOR HIM. THE MLG WAS LEVELING OFF FROM DSCNT AND AT RELATIVELY LOW AIRSPD (CLEAN CONFIGN AND DECELERATING TO 250 KTS). THIS PUTS IT NOSE HIGH MAKING IT MORE DIFFICULT TO DETECT TFC AHEAD OF AND BELOW THE NOSE. TO PREVENT RECURRENCE: ELIMINATE RADAR FAULTINESS, CONTINUE SEEING AND AVOIDING, DECREASE CTLR WORKLOAD.

Data retrieved from NASA's ASRS site as of August 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.