A DHC8B CREW TOOK EVASIVE ACTION ON DEP.

Narrative

WHILE WE WERE HOLDING AT THE DEP END OF RWY 10L; WE HEARD PDX TWR CTLR CLR A CESSNA TO CROSS MIDFIELD AND ENTER A N OR L DOWNWIND TO RWY 10L. THE CTLR THEN CLRED US FOR TKOF. IN MY MIND THERE WAS ABSOLUTELY NO CHANCE OF A PROB BECAUSE THIS OVERHEAD XING TFC WOULD BE WELL BEHIND US AND MUCH HIGHER. IMMEDIATELY AFTER DEP WE ENCOUNTERED THE C210 ABOUT 1 1/2 MI OFF THE DEP END OF RWY 10L DSNDING AND TURNING TOWARD US FROM APPROX 1000 FT AGL. OBVIOUSLY THE CESSNA HAD NOT COMPLIED WITH HIS INSTRUCTIONS AND WAS ACTUALLY MUCH CLOSER TO THE XWIND LEG. ALSO; THE TWR CTLR HAD NOT VERIFIED THAT HE HAD COMPLIED WITH HER INSTRUCTIONS. OUR ACCELERATION HEIGHT TO CLEAN UP OUR TKOF CONFIGN (FLAPS UP) WAS 688 FT; WHICH WE NEVER REACHED. I REDUCED CLB PWR AND PERFORMED A DSNDING L-HAND TURN TO AVOID A COLLISION. WE EXCEEDED THE TKOF FLAP SPD LIMITATION DURING THIS MANEUVER. WE DEPARTED THE SID FOR A BIT TO FLY OUR EVASIVE MANEUVER. THE TCASII ONCE AGAIN WAS A VALUABLE TOOL. LUCKILY; I SIGHTED THE TFC AT OUR 2 O'CLOCK POS ONCE WE GOT THE GEAR UP. I THEN USED THE TCASII TO PLAN MY ESCAPE RTE. WE NEVER GOT A TA OR RA BECAUSE I KNEW AT OUR RAPID CLB RATE WE MIGHT POSSIBLY COLLIDE WITH THE AIRPLANE IF WE WAITED THAT LONG. SO I BEGAN MY EVASIVE MANEUVERING AS SOON AS I SAW THE CESSNA. SUPPLEMENTAL INFO FROM ACN 500613: I THINK I MAY HAVE BEEN A LITTLE E OF MIDFIELD AND A LITTLE SLOW TO START MY L TURN TO DOWNWIND. I MAY HAVE DSNDED A LITTLE TOO QUICKLY FROM OVER THE TWR AND NOT HEARD MAINTAIN 1500 FT UNTIL N OF THE TWR. I KNOW I WAS N OF THE TWR AND E 100 FT OR SO. ANOTHER PLT WAS IN THE PAX SEAT TO MY R AND COMMENTED THAT THE DEPARTING FLT PASSED UNDER US. IT WAS DARK. I ASKED HIM IF IT WAS CLOSE. HE SAID IT WAS HARD TO TELL; BUT MAYBE 300-400 FT BTWN US.